NanoBioelectronics and Biosensors
Group Leader: Arben Merkoçi
Publications
2024
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An α-helical peptide-based plasmonic biosensor for highly specific detection of α-synuclein-toxic oligomers
Juliana de Fátima Giarola; Jaime Santos; M.‐Carmen Estévez; Salvador Ventura; Irantzu Pallarès; Laura M. Lechuga Analytica Chimica Acta; 1304: 342559 - 342559. 2024. 10.1016/j.aca.2024.342559. IF: 5.700
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Capacitive immunosensing at gold nanoparticle-decorated reduced graphene oxide electrodes fabricated by one-step laser nanostructuration
Echeverri, Danilo; Calucho, Enric; Marrugo-Ramirez, Jose; Alvarez-Diduk, Ruslan; Orozco, Jahir; Merkoci, Arben Biosensors & Bioelectronics; 252: 116142. 2024. 10.1016/j.bios.2024.116142. IF: 10.700
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Editorial on Crossing the laboratory borders. Volume I – Health: biosensors and diagnostic tools from the lab to the fab
Giulio Rosati; Arben Merkoçi; Ruslán Álvarez-Diduk; Anja Boisen; Alan Thomson Biosensors & Bioelectronics/Biosensors & Bioelectronics (Online); : 116557 - 116557. 2024. 10.1016/j.bios.2024.116557.
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Harnessing Bioluminescent Bacteria to Develop an Enzymatic-free Enzyme-linked immunosorbent assay for the Detection of Clinically Relevant Biomarkers
Rossetti, Marianna Acs Applied Materials & Interfaces; 2024. 10.1021/acsami.4c01744. IF: 8.300
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Low-cost inkjet-printed nanostructured biosensor based on CRISPR/Cas12a system for pathogen detection
Rossetti, Marianna Biosensors And Bioelectronics; : 116340. 2024. 10.1016/j.bios.2024.116340.
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Nanostructure Tuning of Gold Nanoparticles Films via Click Sintering
Urban, Massimo; Rosati, Giulio; Maroli, Gabriel; Pelle, Flavio Della; Bonini, Andrea; Sajti, Laszlo; Fedel, Mariangela; Merkoci, Arben Small; 20 (13): e2306167 - e2306167. 2024. 10.1002/smll.202306167. IF: 13.000
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Reduced graphene oxide electrodes meet lateral flow assays: A promising path to advanced point-of-care diagnostics
Calucho Palma, Enric Biosensors And Bioelectronics; 258: 116315. 2024. 10.1016/j.bios.2024.116315.
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Studying ion transport dynamics in electrochemical measurements of lateral flow assays
Le Brun, Gregoire; Calucho, Enric; Hauwaert, Margo; Moumneh, Ramy; Maroli, Gabriel; Yunus, Sami; Rosati, Giulio; Alvarez-Diduk, Ruslan; Piper, Andrew; Merkoci, Arben; Raskin, Jean- Pierre Journal Of Electroanalytical Chemistry; 966: 118399. 2024. 10.1016/j.jelechem.2024.118399. IF: 4.100
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Unleashing inkjet-printed nanostructured electrodes and battery-free potentiostat for the DNA-based multiplexed detection of SARS-CoV-2 genes
Rossetti, Marianna; Srisomwat, Chawin; Urban, Massimo; Rosati, Giulio; Maroli, Gabriel; Akbay, Hatice Godze Iraman; Chailapakul, Orawon; Merkoci, Arben Biosensors & Bioelectronics; 250: 116079. 2024. 10.1016/j.bios.2024.116079. IF: 10.700
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Wearable, battery-free, wireless multiplexed printed sensors for heat stroke prevention with mussel-inspired bio-adhesive membranes
Maroli, Gabriel; Rosati, Giulio; Suarez-Garcia, Salvio; Bedmar-Romero, Daniel; Kobrin, Robert; Gonzalez-Laredo, Alvaro; Urban, Massimo; Alvarez-Diduk, Ruslan; Ruiz-Molina, Daniel; Merkoci, Arben Biosensors & Bioelectronics; 260: 116421. 2024. 10.1016/j.bios.2024.116421. IF: 10.700
2023
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Advanced Materials for Biosensors - Special Issue of SMALL
Merkoçi, A Small; 19 (51): 2308049. 2023. 10.1002/smll.202308049. IF: 13.300
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An Artificial Miniaturized Peroxidase for Signal Amplification in Lateral Flow Immunoassays
Renzi, E; Piper, A; Nastri, F; Merkoci, A; Lombardi, A Small; 19 (51): e2207949. 2023. 10.1002/smll.202207949. IF: 13.300
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Freestanding laser-induced two dimensional heterostructures for self-contained paper-based sensors
Della Pelle, F; Bukhari, QU; Diduk, RA; Scroccarello, A; Compagnone, D; Merkoci, A Nanoscale; 15 (15): 7164 - 7175. 2023. 10.1039/d2nr07157f. IF: 6.700
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Laser Reduced Graphene Oxide Electrode for Pathogenic Escherichia coli Detection
Zhao, L; Rosati, G; Piper, A; Silva, CDCE; Hu, LM; Yang, QY; Pelle, FD; Alvarez-Diduk, RR; Merkoci, A Acs Applied Materials & Interfaces; 2023. 10.1021/acsami.2c20859. IF: 9.500
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Metal-free cysteamine-functionalized graphene alleviates mutual interferences in heavy metal electrochemical detection
Yang, QY; Nguyen, EP; Panacek, D; Sedajova, V; Hruby, V; Rosati, G; Silva, CDC; Bakandritsos, A; Otyepka, M; Merkoci, A Green Chemistry; 25 (4): 1647 - 1657. 2023. 10.1039/d2gc02978b. IF: 9.800
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One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications
Scroccarello, A; Alvarez-Diduk, R; Della Pelle, F; Silva, CDCCE; Idili, A; Parolo, C; Compagnone, D; Merkoci, A Acs Sensors; 8 (2): 598 - 609. 2023. 10.1021/acssensors.2c01782. IF: 8.900
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Rational Approach to Tailor Au-IrO2 Nanoflowers as Colorimetric Labels for Lateral Flow Assays
Rivas, L; Merkoci, A; Hu, LM; Parolo, C; Idili, A Acs Applied Nano Materials; 6 (6): 4151 - 4161. 2023. 10.1021/acsanm.2c04915. IF: 5.900
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The Cleanroom-Free, Cheap, and Rapid Fabrication of Nanoelectrodes with Low zM Limits of Detection
Maroli, G; Abarintos, V; Piper, A; Merkoçi, A Small; 19 (51): e2302136 - e2302136. 2023. 10.1002/smll.202302136. IF: 13.300
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Toward Integrated Molecular Lateral Flow Diagnostic Tests Using Advanced Micro- and Nanotechnology
Rubio-Monterde, A; Quesada-Gonzalez, D; Merkoci, A Analytical Chemistry; 95 (1): 468 - 489. 2023. 10.1021/acs.analchem.2c04529. IF: 7.400
2022
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A Novel Ratiometric Fluorescent Approach for the Modulation of the Dynamic Range of Lateral Flow Immunoassays
Sena-Torralba A., Torné-Morató H., Parolo C., Ranjbar S., Farahmand Nejad M.A., Álvarez-Diduk R., Idili A., Hormozi-Nezhad M.R., Merkoçi A. Advanced Materials Technologies; 7 (8, 2101450) 2022. 10.1002/admt.202101450. IF: 7.848
The majority of lateral flow assays (LFAs) use single-color optical labels to provide a qualitative naked-eye detection, however this detection method displays two important limitations. First, the use of a single-color label makes the LFA prone to results misinterpretation. Second, it does not allow the precise modulation of the sensitivity and dynamic range of the test. To overcome these limitations, a ratiometric approach is developed. In particular, using anti-HIgG functionalized red-fluorescent quantum dots on the conjugate pad (as target dependent labels) and blue-fluorescent nanoparticles fixed on the test line (as target independent reporters), it is possible to generate a wide color palette (blue, purple, pink, red) on the test line. It is believed that this strategy will facilitate the development of LFAs by easily adjusting their analytical properties to the needs required by the specific application. © 2022 The Authors. Advanced Materials Technologies published by Wiley-VCH GmbH.
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A plug, print & play inkjet printing and impedance-based biosensing technology operating through a smartphone for clinical diagnostics
Rosati G., Urban M., Zhao L., Yang Q., de Carvalho Castro e Silva C., Bonaldo S., Parolo C., Nguyen E.P., Ortega G., Fornasiero P., Paccagnella A., Merkoçi A. Biosensors and Bioelectronics; 196 (113737) 2022. 10.1016/j.bios.2021.113737. IF: 10.618
Simplicity is one of the key feature for the spread of any successful technological product. Here, a method for rapid and low-cost fabrication of electrochemical biosensors is presented. This “plug, print & play” method involves inkjet-printing even in an office-like environment, without the need of highly specialized expertise or equipment, guaranteeing an ultra-fast idea to (scaled) prototype production time. The printed biosensors can be connected to a smartphone through its audio input for their impedance readout, demonstrating the validity of the system for point-of-care biosensing. Proper electrodes layout guarantees high sensitivity and is validated by finite element simulations. The introduction of a passivation method (wax printing) allowed to complete the devices fabrication process, increasing their sensitivity. Indeed, the wax allowed reducing the interference related to the parasitic currents flowing through the permeable coating of the employed substrates, which was used for the chemical sintering, thus avoiding the common thermal treatment after printing. As a case study, we used the devices to develop an electrochemical aptamer-based sensor for the rapid detection of neutrophil gelatinase-associated lipocalin (NGAL) in urine – a clinically important marker of acute kidney injury. The aptasensor platform is capable of detecting clinically relevant concentrations of NGAL with a simple and rapid smartphone readout. The developed technology may be extended in the future to continuous monitoring, taking advantage of its flexibility to integrate it in tubes, or to other diagnostic applications where cost/efficiency and rapidity of the research, development and implementation of point of care devices is a must. © 2021
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A Programmable Electrochemical Y-Shaped DNA Scaffold Sensor for the Single-Step Detection of Antibodies and Proteins in Untreated Biological Fluids
Idili A., Bonini A., Parolo C., Alvarez-Diduk R., Di Francesco F., Merkoçi A. Advanced Functional Materials; 2022. 10.1002/adfm.202201881.
Proteins and antibodies are key biomarkers for diagnosing and monitoring specific medical conditions. Currently, gold standard techniques used for their quantification require laborious multi-step procedures, involving high costs and slow response times. It is possible to overcome these limitations by exploiting the chemistry and programmability of DNA to design a reagentless electrochemical sensing platform. Specifically, three DNA single strands are engineered that can self-assemble into a Y-shaped DNA nanostructure that resembles one of the IgGs. In order to convert this DNA nanostructure into a responsive DNA-scaffold bioreceptor, it is modified including two recognition elements, two redox tag molecules, and a thiol group. In the absence of the target, the scaffold receptor can efficiently collide with the electrode surface and generate a strong electrochemical signal. The presence of the target induces its bivalent binding, which produces steric hindrance interactions that limit the receptor's collisional activity. In its bound state, the redox tags can therefore approach the surface at a slower rate, leading to a signal decrease that is quantitatively related to the target concentration. The Y-shape DNA scaffold sensor can detect nanomolar concentrations of antibodies and proteins in <15 min with a single-step procedure directly in untreated biological fluids. © 2022 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.
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An innovative autonomous robotic system for on-site detection of heavy metal pollution plumes in surface water
De Vito-Francesco E., Farinelli A., Yang Q., Nagar B., Álvarez R., Merkoçi A., Knutz T., Haider A., Stach W., Ziegenbalg F., Allabashi R. Environmental Monitoring and Assessment; 194 (2, 122) 2022. 10.1007/s10661-021-09738-z. IF: 2.513
Smart monitoring has been studied and developed in recent years to create faster, cheaper, and more user-friendly on-site methods. The present study describes an innovative technology for investigative monitoring of heavy metal pollution (Cu and Pb) in surface water. It is composed of an autonomous surface vehicle capable of semiautonomous driving and equipped with a microfluidic device for detection of heavy metals. Detection is based on the method of square wave anodic stripping voltammetry using carbon-based screen-printed electrodes (SPEs). The focus of this work was to validate the ability of the integrated system to perform on-site detection of heavy metal pollution plumes in river catchments. This scenario was simulated in laboratory experiments. The main performance characteristics of the system, which was evaluated based on ISO 15839 were measurement bias (Pb 75%, Cu 65%), reproducibility (in terms of relative standard deviation: Pb 11–18%, Cu 6–10%) and the limit of detection (4 µg/L for Pb and 7 µg/L for Cu). The lowest detectable change (LDC), which is an important performance characteristic for this application, was estimated to be 4–5 µg/L for Pb and 6–7 µg/L for Cu. The life span of an SPE averaged 39 measurements per day, which is considered sufficient for intended monitoring campaigns. This work demonstrated the suitability of the integrated system for on-site detection of Pb and Cu emissions from large and medium urban areas discharging into small water bodies. © 2022, The Author(s).
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Editorial on COVID-19 biosensing technologies- 2d Edition
Merkoçi A., Li C.-Z., Lechuga L.M., Ozcan A. Biosensors and Bioelectronics; 212 (114340) 2022. 10.1016/j.bios.2022.114340.
[No abstract available]
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Graphene Nanobeacons with High-Affinity Pockets for Combined, Selective, and Effective Decontamination and Reagentless Detection of Heavy Metals
Panáček D., Zdražil L., Langer M., Šedajová V., Baďura Z., Zoppellaro G., Yang Q., Nguyen E.P., Álvarez-Diduk R., Hrubý V., Kolařík J., Chalmpes N., Bourlinos A.B., Zbořil R., Merkoçi A., Bakandritsos A., Otyepka M. Small; 18 (33, 2201003) 2022. 10.1002/smll.202201003.
Access to clean water for drinking, sanitation, and irrigation is a major sustainable development goal of the United Nations. Thus, technologies for cleaning water and quality-monitoring must become widely accessible and of low-cost, while being effective, selective, sustainable, and eco-friendly. To meet this challenge, hetero-bifunctional nanographene fluorescent beacons with high-affinity pockets for heavy metals are developed, offering top-rated and selective adsorption for cadmium and lead, reaching 870 and 450 mg g-1, respectively. The heterobifunctional and multidentate pockets also operate as selective gates for fluorescence signal regulation with sub-nanomolar sensitivity (0.1 and 0.2 nm for Pb2+ and Cd2+, respectively), due to binding affinities as low as those of antigen-antibody interactions. Importantly, the acid-proof nanographenes can be fully regenerated and reused. Their broad visible-light absorption offers an additional mode for water-quality monitoring based on ultra-low cost and user-friendly reagentless paper detection with the naked-eye at a limit of detection of 1 and 10 ppb for Pb2+ and Cd2+ ions, respectively. This work shows that photoactive nanomaterials, densely-functionalized with strong, yet selective ligands for targeted contaminants, can successfully combine features such as excellent adsorption, reusability, and sensing capabilities, in a way to extend the material's applicability, its life-cycle, and value-for-money. © 2022 The Authors. Small published by Wiley-VCH GmbH.
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Label-free and reagentless electrochemical genosensor based on graphene acid for meat adulteration detection
Flauzino J.M.R., Nguyen E.P., Yang Q., Rosati G., Panáček D., Brito-Madurro A.G., Madurro J.M., Bakandritsos A., Otyepka M., Merkoçi A. Biosensors and Bioelectronics; 195 (113628) 2022. 10.1016/j.bios.2021.113628. IF: 10.618
With the increased demand for beef in emerging markets, the development of quality-control diagnostics that are fast, cheap and easy to handle is essential. Especially where beef must be free from pork residues, due to religious, cultural or allergic reasons, the availability of such diagnostic tools is crucial. In this work, we report a label-free impedimetric genosensor for the sensitive detection of pork residues in meat, by leveraging the biosensing capabilities of graphene acid - a densely and selectively functionalized graphene derivative. A single stranded DNA probe, specific for the pork mitochondrial genome, was immobilized onto carbon screen-printed electrodes modified with graphene acid. It was demonstrated that graphene acid improved the charge transport properties of the electrode, following a simple and rapid electrode modification and detection protocol. Using non-faradaic electrochemical impedance spectroscopy, which does not require any electrochemical indicators or redox pairs, the detection of pork residues in beef was achieved in less than 45 min (including sample preparation), with a limit of detection of 9% w/w pork content in beef samples. Importantly, the sample did not need to be purified or amplified, and the biosensor retained its performance properties unchanged for at least 4 weeks. This set of features places the present pork DNA sensor among the most attractive for further development and commercialization. Furthermore, it paves the way for the development of sensitive and selective point-of-need sensing devices for label-free, fast, simple and reliable monitoring of meat purity. © 2021
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Low-Cost, User-Friendly, All-Integrated Smartphone-Based Microplate Reader for Optical-Based Biological and Chemical Analyses
Bergua J.F., Álvarez-Diduk R., Idili A., Parolo C., Maymó M., Hu L., Merkoçi A. Analytical Chemistry; 94 (2): 1271 - 1285. 2022. 10.1021/acs.analchem.1c04491. IF: 6.986
The quantitative detection of different molecular targets is of utmost importance for a variety of human activities, ranging from healthcare to environmental studies. Bioanalytical methods have been developed to solve this and to achieve the quantification of multiple targets from small volume samples. Generally, they can be divided into two different classes: point of care (PoC) and laboratory-based approaches. The former is rapid, low-cost, and user-friendly; however, the majority of the tests are semiquantitative, lacking in specificity and sensitivity. On the contrary, laboratory-based approaches provide high sensitivity and specificity, but the bulkiness of experimental instruments and complicated protocols hamper their use in resource-limited settings. In response, here we propose a smartphone-based device able to support laboratory-based optical techniques directly at the point of care. Specifically, we designed and fabricated a portable microplate reader that supports colorimetric, fluorescence, luminescence, and turbidity analyses. To demonstrate the potential of the device, we characterized its analytical performance by detecting a variety of relevant molecular targets (ranging from antibodies, toxins, drugs, and classic fluorophore dyes) and we showed how the estimated results are comparable to those obtained from a commercial microplate reader. Thanks to its low cost (<$300), portability (27 cm [length] × 18 cm [width] × 7 cm [height]), commercially available components, and open-source-based system, we believe it represents a valid approach to bring high-precision laboratory-based analysis at the point of care. © 2022 The Authors. Published by American Chemical Society
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Metabolomics for personalized medicine: the input of analytical chemistry from biomarker discovery to point-of-care tests
Castelli F.A., Rosati G., Moguet C., Fuentes C., Marrugo-Ramírez J., Lefebvre T., Volland H., Merkoçi A., Simon S., Fenaille F., Junot C. Analytical and Bioanalytical Chemistry; 414 (2): 759 - 789. 2022. 10.1007/s00216-021-03586-z. IF: 4.142
Metabolomics refers to the large-scale detection, quantification, and analysis of small molecules (metabolites) in biological media. Although metabolomics, alone or combined with other omics data, has already demonstrated its relevance for patient stratification in the frame of research projects and clinical studies, much remains to be done to move this approach to the clinical practice. This is especially true in the perspective of being applied to personalized/precision medicine, which aims at stratifying patients according to their risk of developing diseases, and tailoring medical treatments of patients according to individual characteristics in order to improve their efficacy and limit their toxicity. In this review article, we discuss the main challenges linked to analytical chemistry that need to be addressed to foster the implementation of metabolomics in the clinics and the use of the data produced by this approach in personalized medicine. First of all, there are already well-known issues related to untargeted metabolomics workflows at the levels of data production (lack of standardization), metabolite identification (small proportion of annotated features and identified metabolites), and data processing (from automatic detection of features to multi-omic data integration) that hamper the inter-operability and reusability of metabolomics data. Furthermore, the outputs of metabolomics workflows are complex molecular signatures of few tens of metabolites, often with small abundance variations, and obtained with expensive laboratory equipment. It is thus necessary to simplify these molecular signatures so that they can be produced and used in the field. This last point, which is still poorly addressed by the metabolomics community, may be crucial in a near future with the increased availability of molecular signatures of medical relevance and the increased societal demand for participatory medicine. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Author(s).
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Paper-based biosensors for cancer diagnostics
Pereira C., Parolo C., Idili A., Gomis R.R., Rodrigues L., Sales G., Merkoçi A. Trends in Chemistry; 4 (6): 554 - 567. 2022. 10.1016/j.trechm.2022.03.005.
The implementation of a wide diagnostic campaign to diagnose cancer early could save millions of lives and billions of dollars every year. Unfortunately, cancer diagnosis is extremely complicated and current approaches rely on the use of expensive equipment and specialized personnel, which hamper their deployment in low- and middle-income settings. Here, we analyze the technical challenges that must be overcome to achieve precise cancer diagnostics and we describe how such hurdles have limited the development of point-of-care (PoC) sensors. Then, we explain why we believe recent achievements in the field of paper-based sensors could allow their use as widely available sensing platforms for cancer detection. Finally, we present our vision of what should be done in order to make paper-based sensors widely used diagnostics platforms for cancer. © 2022 Elsevier Inc.
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Selection and characterisation of bioreceptors to develop nanoparticle-based lateral-flow immunoassays in the context of the SARS-CoV-2 outbreak
Hu L., Calucho E., Fuentes-Chust C., Parolo C., Idili A., Álvarez-Diduk R., Rivas L., Merkoçi A. Lab on a Chip; 22 (16): 2938 - 2943. 2022. 10.1039/d2lc00486k.
This manuscript aims at raising the attention of the scientific community to the need for better characterised bioreceptors for fast development of point-of-care diagnostic devices able to support mass frequency testing. Particularly, we present the difficulties encountered in finding suitable antibodies for the development of a lateral flow assay for detecting the nucleoprotein of SARS-CoV-2. © 2022 The Royal Society of Chemistry.
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Toward Next Generation Lateral Flow Assays: Integration of Nanomaterials
Sena-Torralba A., Álvarez-Diduk R., Parolo C., Piper A., Merkoçi A. Chemical Reviews; 122 (18): 14881 - 14910. 2022. 10.1021/acs.chemrev.1c01012.
Lateral flow assays (LFAs) are currently the most used point-of-care sensors for both diagnostic (e.g., pregnancy test, COVID-19 monitoring) and environmental (e.g., pesticides and bacterial monitoring) applications. Although the core of LFA technology was developed several decades ago, in recent years the integration of novel nanomaterials as signal transducers or receptor immobilization platforms has brought improved analytical capabilities. In this Review, we present how nanomaterial-based LFAs can address the inherent challenges of point-of-care (PoC) diagnostics such as sensitivity enhancement, lowering of detection limits, multiplexing, and quantification of analytes in complex samples. Specifically, we highlight the strategies that can synergistically solve the limitations of current LFAs and that have proven commercial feasibility. Finally, we discuss the barriers toward commercialization and the next generation of LFAs. © 2022 American Chemical Society. All rights reserved.
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Wearable and fully printed microfluidic nanosensor for sweat rate, conductivity, and copper detection with healthcare applications
Yang Q., Rosati G., Abarintos V., Aroca M.A., Osma J.F., Merkoçi A. Biosensors and Bioelectronics; 202 (114005) 2022. 10.1016/j.bios.2022.114005. IF: 10.618
Wearables are becoming pervasive in our society, but they are still mainly based on physical sensors with just few optical and electrochemical exceptions. Sweat, amongst other body fluids, is easily and non-invasively accessible, abundant, and relatively poor of interfering species. The biomarkers of interest in sweat space from ions and small molecules to whole organisms. Heavy metals have been found being biomarkers of several diseases and pathological conditions. Copper in particular is correlated to Wilson's disease and liver cirrhosis among others. Nevertheless, several issues such as sampling conditions, sweat rate normalization, reliable continuous monitoring, and typically expensive fabrication methods still needs to be addressed in sweat analysis with wearables. Herein, we propose a fully printed wearable microfluidic nanosensor with an integrated wireless smartphone-based readout. Our system can easily be applied on the skin and actively stimulate perspiration, normalizing the heavy metals concentration with respect to the volume of the sample and the sweat rate. The system has a limit of detection of 396 ppb, a linear range up to 2500 ppb and a sensitivity of 2.3 nA/ppb. © 2022
2021
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Attomolar analyte sensing techniques (AttoSens): A review on a decade of progress on chemical and biosensing nanoplatforms
Usha S.P., Manoharan H., Deshmukh R., Álvarez-Diduk R., Calucho E., Sai V.V.R., Merkoçi A. Chemical Society Reviews; 50 (23): 13012 - 13089. 2021. 10.1039/d1cs00137j. IF: 54.564
Detecting the ultra-low abundance of analytes in real-life samples, such as biological fluids, water, soil, and food, requires the design and development of high-performance biosensing modalities. The breakthrough efforts from the scientific community have led to the realization of sensing technologies that measure the analyte's ultra-trace level, with relevant sensitivity, selectivity, response time, and sampling efficiency, referred to as Attomolar Analyte Sensing Techniques (AttoSens) in this review. In an AttoSens platform, 1 aM detection corresponds to the quantification of 60 target analyte molecules in 100 μL of sample volume. Herein, we review the approaches listed for various sensor probe design, and their sensing strategies that paved the way for the detection of attomolar (aM: 10-18 M) concentration of analytes. A summary of the technological advances made by the diverse AttoSens trends from the past decade is presented. This journal is © The Royal Society of Chemistry.
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COVID-19 biosensing technologies
Merkoçi A., Li C.-Z., Lechuga L.M., Ozcan A. Biosensors and Bioelectronics; 178 (113046) 2021. 10.1016/j.bios.2021.113046. IF: 10.618
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Development of a Heavy Metal Sensing Boat for Automatic Analysis in Natural Waters Utilizing Anodic Stripping Voltammetry
Qiuyue Yang,Bhawna Nagar,Ruslán Alvarez-Diduk,Marc Balsells,Alessandro Farinelli,Domenico Bloisi, Lorenzo Proia, Carmen Espinosa, Marc Ordeix, Thorsten Knutz,Elisabetta De Vito-Francesco, Roza Allabashi, Arben Merkoçi Acs Es&t Water; 1 (12): 2470 - 2476. 2021. 10.1021/acsestwater.1c00192. IF: 0.000
Determination of the levels of heavy metal ions would support assessment of sources and pathways of water pollution. However, traditional spatial assessment by manual sampling and off-site detection in the laboratory is expensive and time-consuming and requires trained personnel. Aiming to fill the gap between on-site automatic approaches and laboratory techniques, we developed an autonomous sensing boat for on-site heavy metal detection using square-wave anodic stripping voltammetry. A fluidic sensing system was developed to integrate into the boat as the critical sensing component and could detect ≤1 μg/L Pb, ≤6 μg/L Cu, and ≤71 μg/L Cd simultaneously in the laboratory. Once its integration was completed, the autonomous sensing boat was tested in the field, demonstrating its ability to distinguish the highest concentration of Pb in an effluent of a galena-enriched mine compared to those at other sites in the stream (Osor Stream, Girona, Spain).
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Electrochromism: An emerging and promising approach in (bio)sensing technology
Farahmand Nejad M.A., Ranjbar S., Parolo C., Nguyen E.P., Álvarez-Diduk R., Hormozi-Nezhad M.R., Merkoçi A. Materials Today; 50: 476 - 498. 2021. 10.1016/j.mattod.2021.06.015. IF: 31.041
Electrochromism (EC) is a unique property of certain materials that undergo an electrochemical-induced change in colouration. During the last decades, electrochromic materials (ECMs) have been applied in a variety of technologies ranging from smart windows to information displays and energy storage devices. More recently, ECMs have attracted the attention of the (bio)sensing community thanks to their ability to combine the sensitivity of electrochemical methods with the intuitive readout of optical sensors. Although still a nascent technology, EC-based sensors are on the rise with several targets (e.g. cancer biomarkers, bacteria, metabolites and pesticides), which have already been detected by (bio)sensors using ECMs as transducers. In this review, we provide the reader with all the information to understand EC and its use in the development of EC-based biosensors. © 2021 Elsevier Ltd
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Improved Aliivibrio fischeri based-toxicity assay: Graphene-oxide as a sensitivity booster with a mobile-phone application
Bergua J.F., Álvarez-Diduk R., Hu L., Hassan A.H.A., Merkoçi A. Journal of Hazardous Materials; 406 (124434) 2021. 10.1016/j.jhazmat.2020.124434. IF: 10.588
Recently, many bioluminescence-based applications have arisen in several fields, such as biosensing, bioimaging, molecular biology, and human health diagnosis. Among all bioluminescent organisms, Aliivibrio fischeri (A. fischeri) is a bioluminescent bacterium used to carry out water toxicity assays since the late 1970s. Since then, several commercial A. fischeri-based products have been launched to the market, as these bacteria are considered as a gold standard for water toxicity assessment worldwide. However, the aforementioned commercial products rely on expensive equipment, requiring several reagents and working steps, as well as high-trained personnel to perform the assays and analyze the output data. For these reasons, in this work, we have developed for the first time a mobile-phone-based sensing platform for water toxicity assessment in just 5 min using two widespread pesticides as model analytes. To accomplish this, we have established new methodologies to enhance the bioluminescent signal of A. fischeri based on the bacterial culture in a solid media and/or using graphene oxide. Finally, we have addressed the biocompatibility of graphene oxide to A. fischeri, boosting the sensitivity of the toxicity assays and the bacterial growth of the lyophilized bacterial cultures for more user-friendly storage. © 2020 Elsevier B.V.
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Integrated Devices for Non-Invasive Diagnostics
Ates H.C., Brunauer A., von Stetten F., Urban G.A., Güder F., Merkoçi A., Früh S.M., Dincer C. Advanced Functional Materials; 31 (15, 2010388) 2021. 10.1002/adfm.202010388. IF: 18.808
“Sample-in-answer-out” type integrated diagnostic devices have been widely recognized as the ultimate solution to simplify testing across healthcare systems. Such systems are equipped with advanced fluidic, mechanical, chemical, biological, and electronic components to handle patient samples without any manual steps therefore have the potential to accelerate intervention and improve patient outcomes. In this regard, the combination of integrated devices and non-invasive sampling has gained a substantial interest to further improve the comfort and safety of patients. In this Review, the pioneering developments in integrated diagnostics are covered and their potential in non-invasive sampling is discussed. The key properties of possible sample types are highlighted by addressing their relevance for the clinical practice. Last, the factors affecting the transition of integrated devices from academia to the market are identified by analyzing the technology readiness levels of selected examples and alternative remedies are explored to increase the rate of survival during this transition. © 2020 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
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Integrating gold nanoclusters, folic acid and reduced graphene oxide for nanosensing of glutathione based on “turn-off” fluorescence
Wong X.Y., Quesada-González D., Manickam S., New S.Y., Muthoosamy K., Merkoçi A. Scientific Reports; 11 (1, 2375) 2021. 10.1038/s41598-021-81677-8. IF: 4.380
Glutathione (GSH) is a useful biomarker in the development, diagnosis and treatment of cancer. However, most of the reported GSH biosensors are expensive, time-consuming and often require complex sample treatment, which limit its biological applications. Herein, a nanobiosensor for the detection of GSH using folic acid-functionalized reduced graphene oxide-modified BSA gold nanoclusters (FA-rGO-BSA/AuNCs) based on the fluorescence quenching interactions is presented. Firstly, a facile and optimized protocol for the fabrication of BSA/AuNCs is developed. Functionalization of rGO with folic acid is performed using EDC/NHS cross-linking reagents, and their interaction after loading with BSA/AuNCs is demonstrated. The formation of FA-rGO, BSA/AuNCs and FA-rGO-BSA/AuNCs are confirmed by the state-of-art characterization techniques. Finally, a fluorescence turn-off sensing strategy is developed using the as-synthesized FA-rGO-BSA/AuNCs for the detection of GSH. The nanobiosensor revealed an excellent sensing performance for the detection of GSH with high sensitivity and desirable selectivity over other potential interfering species. The fluorescence quenching is linearly proportional to the concentration of GSH between 0 and 1.75 µM, with a limit of detection of 0.1 µM under the physiological pH conditions (pH 7.4). Such a sensitive nanobiosensor paves the way to fabricate a “turn-on” or “turn-off” fluorescent sensor for important biomarkers in cancer cells, presenting potential nanotheranostic applications in biological detection and clinical diagnosis. © 2021, The Author(s).
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Lateral flow device for water fecal pollution assessment: From troubleshooting of its microfluidics using bioluminescence to colorimetric monitoring of genericEscherichia coli
Bergua J.F., Hu L., Fuentes-Chust C., Álvarez-Diduk R., Hassan A.H.A., Parolo C., Merkoçi A. Lab on a Chip; 21 (12): 2417 - 2426. 2021. 10.1039/d1lc00090j. IF: 6.799
Water is the most important ingredient of life. Water fecal pollution threatens water quality worldwide and has direct detrimental effects on human health and the global economy. Nowadays, assessment of water fecal pollution relies on time-consuming techniques that often require well-trained personnel and highly-equipped laboratories. Therefore, faster, cheaper, and easily-used systems are needed toin situmonitor water fecal pollution. Herein, we have developed colorimetric lateral flow strips (LFS) able to detect and quantifyEscherichia colispecies in tap, river, and sewage water samples as an indicator of fecal pollution. The combination of LFS with a simple water filtration unit and a commercially available colorimetric reader enhanced the assay sensitivity and enabled more accurate quantification of bacteria concentration down to 104CFU mL−1in 10 minutes, yielding recovery percentages between 80% and 90% for all water samples analyzed. Overall, this system allows for monitoring and assessing water quality based onE. colispecies as a standard microbiological indicator of fecal pollution. Furthermore, we have developed a novel bioluminescent, bacteria-based method to quickly characterize the performance of a great variety of LFS materials. This new method allows evaluating the flow rate of big analytes such as bacteria through the LFS materials, as a suggestive means for selecting the appropriate materials for fabricating LFS targeting big analytes (≈2 μm). As a whole, the proposed approach can accelerate and reduce the costs of water quality monitoring and pave the way for further improvement of fecal pollution detection systems. © The Royal Society of Chemistry 2021.
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Nanodiagnostics to Face SARS-CoV-2 and Future Pandemics: From an Idea to the Market and beyond
Rosati G., Idili A., Parolo C., Fuentes-Chust C., Calucho E., Hu L., Castro E Silva C.D.C., Rivas L., Nguyen E.P., Bergua J.F., Alvárez-Diduk R., Muñoz J., Junot C., Penon O., Monferrer D., Delamarche E., Merkoçi A. ACS Nano; 15 (11): 17137 - 17149. 2021. 10.1021/acsnano.1c06839. IF: 15.881
The COVID-19 pandemic made clear how our society requires quickly available tools to address emerging healthcare issues. Diagnostic assays and devices are used every day to screen for COVID-19 positive patients, with the aim to decide the appropriate treatment and containment measures. In this context, we would have expected to see the use of the most recent diagnostic technologies worldwide, including the advanced ones such as nano-biosensors capable to provide faster, more sensitive, cheaper, and high-throughput results than the standard polymerase chain reaction and lateral flow assays. Here we discuss why that has not been the case and why all the exciting diagnostic strategies published on a daily basis in peer-reviewed journals are not yet successful in reaching the market and being implemented in the clinical practice. ©
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Paper-based electrophoretic bioassay: Biosensing in whole blood operating via smartphone
Merkoçi A., Sena-Torralba A., Alvarez-Diduk R., Parolo C., Torné-Morató H., Müller A. Analytical Chemistry; 93 (6): 3112 - 3121. 2021. 10.1021/acs.analchem.0c04330. IF: 6.986
Point-of-care (PoC) tests are practical and effective diagnostic solutions for major clinical problems, ranging from the monitoring of a pandemic to recurrent or simple measurements. Although, in recent years, a great improvement in the analytical performance of such sensors has been observed, there is still a major issue that has not been properly solved: The ability to perform adequate sample treatments. The main reason is that normally sample treatments require complicated or long procedures not adequate for deployment at the PoC. In response, a sensing platform, called paperbased electrophoretic bioassay (PEB), that combines the key characteristics of a lateral flow assay (LFA) with the sample treatment capabilities of electrophoresis is developed. In particular, the ability of PEB to separate different types of particles and to detect human antibodies in untreated spiked whole blood is demonstrated. Finally, to make the platform suitable for PoC, PEB is coupled with a smartphone that controls the electrophoresis and reads the optical signal generated. It is believed that the PEB platform represents a much-needed solution for the detection of low target concentrations in complex media, solving one of the major limitations of LFA and opening opportunities for point-of-care sensors. © 2021 American Chemical Society.
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Rapid and Efficient Detection of the SARS-CoV-2 Spike Protein Using an Electrochemical Aptamer-Based Sensor
Idili A., Parolo C., Alvarez-Diduk R., Merkoçi A. ACS Sensors; 6 (8): 3093 - 3101. 2021. 10.1021/acssensors.1c01222. IF: 7.711
The availability of sensors able to rapidly detect SARS-CoV-2 directly in biological fluids in a single step would allow performing massive diagnostic testing to track in real time and contain the spread of COVID-19. Motivated by this, here, we developed an electrochemical aptamer-based (EAB) sensor able to achieve the rapid, reagentless, and quantitative measurement of the SARS-CoV-2 spike (S) protein. First, we demonstrated the ability of the selected aptamer to undergo a binding-induced conformational change in the presence of its target using fluorescence spectroscopy. Then, we engineered the aptamer to work as a bioreceptor in the EAB platform and we demonstrated its sensitivity and specificity. Finally, to demonstrate the clinical potential of the sensor, we tested it directly in biological fluids (serum and artificial saliva), achieving the rapid (minutes) and single-step detection of the S protein in its clinical range. © 2021 American Chemical Society.
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Smart nanobiosensors in agriculture
Merkoçi A. Nature Food; 2 (12): 920 - 921. 2021. 10.1038/s43016-021-00426-2. IF: 0.000
[No abstract available]
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The Microbiome Meets Nanotechnology: Opportunities and Challenges in Developing New Diagnostic Devices
Fuentes-Chust C., Parolo C., Rosati G., Rivas L., Perez-Toralla K., Simon S., de Lecuona I., Junot C., Trebicka J., Merkoçi A. Advanced Materials; 33 (18, 2006104) 2021. 10.1002/adma.202006104. IF: 30.849
Monitoring of the human microbiome is an emerging area of diagnostics for personalized medicine. Here, the potential of different nanomaterials and nanobiosensing technologies is reviewed for the development of novel diagnostic devices for the detection and measurement of microbiome-related biomarkers. Moreover, the current and future landscape of microbiome-based diagnostics is defined by exploring the advantages and disadvantages of current nanotechnology-based approaches, especially in the context of developing point-of-care (PoC) devices that would meet the international guidelines known as REASSURED (Real-time connectivity; Ease of specimen collection; Affordability; Sensitivity; Specificity; User-friendliness; Rapid & robust operation; Equipment-free; and Deliverability). Finally, the strategies of the latest international scientific consortia working in this field are analyzed, the current microbiome diagnostics market are reported and the principal ethical, legal, and societal issues related to microbiome R&D and innovation are discussed. © 2021 Wiley-VCH GmbH
2020
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2-dimensional materials-based electrical/optical platforms for smart on-off diagnostics applications
Kou J., Nguyen E.P., Merkoçi A., Guo Z. 2D Materials; 7 (3, 032001) 2020. 10.1088/2053-1583/ab896a. IF: 7.140
The concept of two-dimensional (2D) materials was first proposed after the first successful separation of graphene, a monoatomic layered material. 2D materials are referred to materials in which electrons can only move freely on the nanoscale in two dimensions, and have expanded to also include the transition metal dichalcogenides (TMDs), black phosphorus (BP) and hexagonal boron nitride (hBN). Different 2D materials have unique electrical or optical characteristics due to the special properties of the crystal structure, and are widely used as field-effect transistors and optoelectronic devices. Moreover, based on the electrochemical and fluorescence quenching properties, many researchers have developed and fabricated light-switching and current-switching sensors for various medical diagnostics. In this paper, we summarize the characteristics of 2D materials and introduce their photoelectric properties, and review the recent applications of 2D materials based switching sensors for the diagnosis of various diseases. © 2020 IOP Publishing Ltd.
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Chitin Nanofiber Paper toward Optical (Bio)sensing Applications
Naghdi T., Golmohammadi H., Yousefi H., Hosseinifard M., Kostiv U., Horák D., Merkoçi A. ACS Applied Materials and Interfaces; 12 (13): 15538 - 15552. 2020. 10.1021/acsami.9b23487. IF: 8.758
Because of numerous inherent and unrivaled features of nanofibers made of chitin, the second most plentiful natural-based polymer (after cellulose), including affordability, abundant nature, biodegradability, biocompatibility, commercial availability, flexibility, transparency, and extraordinary mechanical and physicochemical properties, chitin nanofibers (ChNFs) are being applied as one of the most appealing bionanomaterials in a myriad of fields. Herein, we exploited the beneficial properties offered by the ChNF paper to fabricate transparent, efficient, biocompatible, flexible, and miniaturized optical sensing bioplatforms via embedding/immobilizing various plasmonic nanoparticles (silver and gold nanoparticles), photoluminescent nanoparticles (CdTe quantum dots, carbon dots, and NaYF4:Yb3+@Er3+&SiO2 upconversion nanoparticles) along with colorimetric reagents (curcumin, dithizone, etc.) in the 3D nanonetwork scaffold of the ChNF paper. Several configurations, including 2D multi-wall and 2D cuvette patterns with hydrophobic barriers/walls and hydrophilic test zones/channels, were easily printed using laser printing technology or punched as spot patterns on the dried ChNF paper-based nanocomposites to fabricate the (bio)sensing platforms. A variety of (bio)chemicals as model analytes were used to confirm the efficiency and applicability of the fabricated ChNF paper-based sensing bioplatforms. The developed (bio)sensors were also coupled with smartphone technology to take the advantages of smartphone-based monitoring/sensing devices along with the Internet of Nano Things (IoNT)/the Internet of Medical Things (IoMT) concepts for easy-to-use sensing applications. Building upon the unrivaled and inherent features of ChNF as a very promising bionanomaterial, we foresee that the ChNF paper-based sensing bioplatforms will emerge new opportunities for the development of innovative strategies to fabricate cost-effective, simple, smart, transparent, biodegradable, miniaturized, flexible, portable, and easy-to-use (bio)sensing/monitoring devices. Copyright © 2020 American Chemical Society.
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Editorial note - Professor Turner's retirement
Gu M.B., Li C., Merkoçi A., the new editorial team of Biosensors and Bioelectronics, Co-Editors in chief Biosensors and Bioelectronics; 150 (111913) 2020. 10.1016/j.bios.2019.111913. IF: 10.257
[No abstract available]
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Experimental Comparison in Sensing Breast Cancer Mutations by Signal on and Signal off Paper-Based Electroanalytical Strips
Cinti S., Cinotti G., Parolo C., Nguyen E.P., Caratelli V., Moscone D., Arduini F., Merkoci A. Analytical Chemistry; 92 (2): 1674 - 1679. 2020. 10.1021/acs.analchem.9b02560. IF: 6.785
The development of paper-based electroanalytical strips as powerful diagnostic tools has gained a lot of attention within the sensor community. In particular, the detection of nucleic acids in complex matrices represents a trending topic, especially when focused toward the development of emerging technologies, such as liquid biopsy. DNA-based biosensors have been largely applied in this direction, and currently, there are two main approaches based on target/probe hybridization reported in the literature, namely Signal ON and Signal OFF. In this technical note, the two approaches are evaluated in combination with paper-based electrodes, using a single strand DNA relative to H1047R (A3140G) missense mutation in exon 20 in breast cancer as the model target. A detailed comparison among the analytical performances, detection protocol, and cost associated with the two systems is provided, highlighting the advantages and drawbacks depending on the application. The present work is aimed to a wide audience, particularly for those in the field of point-of-care, and it is intended to provide the know-how to manage with the design and development stages, and to optimize the platform for the sensing of nucleic acids using a paper-based detection method. © 2019 American Chemical Society.
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Graphene-based biosensors
Merkoi A. 2D Materials; 7 (4, 040401) 2020. 10.1088/2053-1583/aba3bf. IF: 7.140
[No abstract available]
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Highly Loaded Mildly Edge-Oxidized Graphene Nanosheet Dispersions for Large-Scale Inkjet Printing of Electrochemical Sensors
Nagar B., Jović M., Bassetto V.C., Zhu Y., Pick H., Gómez-Romero P., Merkoçi A., Girault H.H., Lesch A. ChemElectroChem; 7 (2): 460 - 468. 2020. 10.1002/celc.201901697. IF: 4.154
Inkjet printing of electrochemical sensors using a highly loaded mildly edge-oxidized graphene nanosheet (EOGN) ink is presented. An ink with 30 mg/mL EOGNs is formulated in a mixture of N-methyl pyrrolidone and propylene glycol with only 30 min of sonication. The absence of additives, such as polymeric stabilizers or surfactants, circumvents reduced electrochemical activity of coated particles and avoids harsh post-printing conditions for additive removal. A single light pulse from a xenon flash lamp dries the printed EGON film within a fraction of a second and creates a compact electrode surface. An accurate coverage with only 30.4 μg of EOGNs per printed layer and cm2 is achieved. The EOGN films adhere well to flexible polyimide substrates in aqueous solution. Electrochemical measurements were performed using cyclic voltammetry and differential pulse voltammetry. An all inkjet-printed three-electrode living bacterial cell detector is prepared with EOGN working and counter electrodes and silver-based quasi-reference electrode. The presence of E. coli in liquid samples is recorded with four electroactive metabolic activity indicators. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Inkjet-printed electrochemically reduced graphene oxide microelectrode as a platform for HT-2 mycotoxin immunoenzymatic biosensing
Kudr J., Zhao L., Nguyen E.P., Arola H., Nevanen T.K., Adam V., Zitka O., Merkoçi A. Biosensors and Bioelectronics; 156 (112109) 2020. 10.1016/j.bios.2020.112109. IF: 10.257
The design and application of an inkjet-printed electrochemically reduced graphene oxide microelectrode for HT-2 mycotoxin immunoenzymatic biosensing is reported. A water-based graphene oxide ink was first formulated and single-drop line working microelectrodes were inkjet-printed onto poly(ethylene 2,6-naphthalate) substrates, with dimensions of 78 μm in width and 30 nm in height after solvent evaporation. The printed graphene oxide microelectrodes were electrochemically reduced and characterized by Raman and X-ray photoelectron spectroscopies in addition to microscopies. Through optimization of the electrochemical reduction parameters, differential pulse voltammetry were performed to examine the sensing of 1-naphthol (1-N), where it was revealed that reduction times had significant effects on electrode performance. The developed microelectrodes were then used as an immunoenzymatic biosensor for the detection of HT-2 mycotoxin based on carbodiimide linking of the microelectrode surface and HT-2 toxin antigen binding fragment of antibody (anti-HT2 (10) Fab). The HT-2 toxin and anti-HT2 (10) Fab reaction was reported by anti-HT2 immune complex single-chain variable fragment of antibody fused with alkaline phosphatase (anti-IC-HT2 scFv-ALP) which is able to produce an electroactive reporter – 1-N. The biosensor showed detection limit of 1.6 ng ∙ mL−1 and a linear dynamic range of 6.3 – 100.0 ng ∙ mL−1 within a 5 min incubation with 1-naphthyl phosphate (1-NP) substrate. © 2020 Elsevier B.V.
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Lab in a Tube: Point-of-Care Detection of Escherichia coli
Amin N., Torralba A.S., Álvarez-Diduk R., Afkhami A., Merkoçi A. Analytical Chemistry; 92 (6): 4209 - 4216. 2020. 10.1021/acs.analchem.9b04369. IF: 6.785
Significant levels of infectious diseases caused by pathogenic bacteria are nowadays a worldwide matter, carrying considerable public health care challenges and huge economic concerns. Because of the rapid transmission of these biothreat agents and the outbreak of diseases, a rapid detection of pathogens in early stages is crucial, particularly in low-resources settings. To this aim, we developed for the first time a new sensing approach carried out in a single step for Escherichia coli O157:H7 detection. The detection principle is based on Förster resonance energy transfer using gold nanoclusters as a signal reporter and gold nanoparticles conjugated with antibodies as a quencher. The sensing platform includes an ultraviolet-light-emitting diode to provide the proper excitation and consists of a microtube containing two pieces of fiber glass; one of them is embedded with label-free gold nanoclusters and the other one with gold nanoparticles conjugated with antibodies. Upon the addition of the sample containing bacteria, the florescence of gold nanoclusters is recovered. The assay was evaluated by the naked eye (on/off) and quantitatively with use of a smartphone camera. The biosensor proved to be highly specific and sensitive, achieving a limit of detection as low as 4.0 cfu mL-1. Additionally, recoveries of 110% and 95% were obtained when the platforms in spiked river and tap water, respectively, were evaluated. Copyright © 2020 American Chemical Society.
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Lateral flow assay modified with time-delay wax barriers as a sensitivity and signal enhancement strategy
Sena-Torralba A., Ngo D.B., Parolo C., Hu L., Álvarez-Diduk R., Bergua J.F., Rosati G., Surareungchai W., Merkoçi A. Biosensors and Bioelectronics; 168 (112559) 2020. 10.1016/j.bios.2020.112559. IF: 10.257
The ease of use, low cost and quick operation of lateral flow assays (LFA) have made them some of the most common point of care biosensors in a variety of fields. However, their generally low sensitivity has limited their use for more challenging applications, where the detection of low analytic concentrations is required. Here we propose the use of soluble wax barriers to selectively and temporarily accumulate the target and label nanoparticles on top of the test line (TL). This extended internal incubation step promotes the formation of the immune-complex, generating a 51.7-fold sensitivity enhancement, considering the limit of quantification, and up to 96% signal enhancement compared to the conventional LFA for Human IgG (H-IgG) detection. © 2020 Elsevier B.V.
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Nano-lantern on paper for smartphone-based ATP detection
Calabretta M.M., Álvarez-Diduk R., Michelini E., Roda A., Merkoçi A. Biosensors and Bioelectronics; 150 (111902) 2020. 10.1016/j.bios.2019.111902. IF: 10.257
ATP-driven bioluminescence relying on the D-luciferin-luciferase reaction is widely employed for several biosensing applications where bacterial ATP detection allows to verify microbial contamination for hygiene monitoring in hospitals, food processing and in general for cell viability studies. Several ATP kit assays are already commercially available but an user-friendly ATP biosensor characterized by low-cost, portability, and adequate sensitivity would be highly valuable for rapid and facile on site screening. Thanks to an innovative freeze-drying procedure, we developed a user-friendly, ready-to-use and stable ATP sensing paper biosensor that can be combined with smartphone detection. The ATP sensing paper includes a lyophilized “nano-lantern” with reaction components being rapidly reconstituted by 10 μL sample addition, enabling detection of 10−14 mol of ATP within 10 min. We analysed urinary microbial ATP as a biomarker of urinary tract infection (UTI), confirming the capability of the ATP sensing paper to detect the threshold for positivity corresponding to 105 colony-forming units of bacteria per mL of urine. © 2019 Elsevier B.V.
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Nanomaterials for Nanotheranostics: Tuning Their Properties According to Disease Needs
Wong X.Y., Sena-Torralba A., Álvarez-Diduk R., Muthoosamy K., Merkoçi A. ACS Nano; 14 (3): 2585 - 2627. 2020. 10.1021/acsnano.9b08133. IF: 14.588
Nanotheranostics is one of the biggest scientific breakthroughs in nanomedicine. Most of the currently available diagnosis and therapies are invasive, time-consuming, and associated with severe toxic side effects. Nanotheranostics, on the other hand, has the potential to bridge this gap by harnessing the capabilities of nanotechnology and nanomaterials for combined therapeutics and diagnostics with markedly enhanced efficacy. However, nanomaterial applications in nanotheranostics are still in its infancy. This is due to the fact that each disease has a particular microenvironment with well-defined characteristics, which promotes deeper selection criteria of nanomaterials to meet the disease needs. In this review, we have outlined how nanomaterials are designed and tailored for nanotheranostics of cancer and other diseases such as neurodegenerative, autoimmune (particularly on rheumatoid arthritis), and cardiovascular diseases. The penetrability and retention of a nanomaterial in the biological system, the therapeutic strategy used, and the imaging mode selected are some of the aspects discussed for each disease. The specific properties of the nanomaterials in terms of feasibility, physicochemical challenges, progress in clinical trials, its toxicity, and their future application on translational medicine are addressed. Our review meticulously and critically examines the applications of nanotheranostics with various nanomaterials, including graphene, across several diseases, offering a broader perspective of this emerging field. © 2020 American Chemical Society.
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Organic-based field effect transistors for protein detection fabricated by inkjet-printing
Martínez-Domingo C., Conti S., de la Escosura-Muñiz A., Terés L., Merkoçi A., Ramon E. Organic Electronics; 84 (105794) 2020. 10.1016/j.orgel.2020.105794. IF: 3.310
Biosensors based on Organic Field-Effect Transistors (OFETs) have attracted increasing attention due to the possibility of rapid, label-free, and inexpensive detection. Among all the different possibilities, inkjet-printed top-gate organic Field Effect Transistors-Based Biosensors (BioFETs) using a polymeric gate insulator have been seldom reported. In this work, a systematic investigation in terms of topographical and electrical characterization was carried out in order to find the optimal fabrication process for obtaining a reliable polymer insulator. Previous studies have demonstrated that the best electrical performance arises from the use of the perfluoropolymer Cytop™[12,13,14]. Consequently, a simple immobilization protocol was used to ensure the proper attachment of a model biomolecule onto the Cytop's hydrophobic surface whilst keeping its remarkable insulating properties with gate current in the range of dozens of pico-amperes. The top-gate inkjet-printed BioFETs presented in this study operate at threshold voltages in the range of 1–2 V and show durability even when exposed to oxygen plasma, wet amine functionalization treatments, and aqueous media. As a preliminary application, the inkjet-printed top-gate BioFETs is used for monitoring an immunoreaction by measuring changes in the drain current, paving the way for further use of this device in the immunosensing field. © 2020 Elsevier B.V.
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Protein-Controlled Actuation of Dynamic Nucleic Acid Networks by Using Synthetic DNA Translators**
Bertucci A., Porchetta A., Del Grosso E., Patiño T., Idili A., Ricci F. Angewandte Chemie - International Edition; 59 (46): 20577 - 20581. 2020. 10.1002/anie.202008553. IF: 12.959
Integrating dynamic DNA nanotechnology with protein-controlled actuation will expand our ability to process molecular information. We have developed a strategy to actuate strand displacement reactions using DNA-binding proteins by engineering synthetic DNA translators that convert specific protein-binding events into trigger inputs through a programmed conformational change. We have constructed synthetic DNA networks responsive to two different DNA-binding proteins, TATA-binding protein and Myc-Max, and demonstrated multi-input activation of strand displacement reactions. We achieved protein-controlled regulation of a synthetic RNA and of an enzyme through artificial DNA-based communication, showing the potential of our molecular system in performing further programmable tasks. © 2020 Wiley-VCH GmbH
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Recent advancement in biomedical applications on the surface of two-dimensional materials: From biosensing to tissue engineering
Nguyen E.P., De Carvalho Castro Silva C., Merkoçi A. Nanoscale; 12 (37): 19043 - 19067. 2020. 10.1039/d0nr05287f. IF: 6.895
As biosensors and biomedical devices have become increasingly important to everyday diagnostics and monitoring, there are tremendous, and constant efforts towards developing and improving the reliability and versatility of such technology. As they offer high surface area-to-volume ratios and a diverse range of properties, from electronic to optical, two dimensional (2D) materials have proven to be very promising candidates for biological applications and technologies. Due to the dimensionality, 2D materials facilitate many interfacial phenomena that have shown to significantly improve the performance of biosensors, while recent advances in synthesis techniques and surface engineering methods also enable the realization of future biomedical devices. This short review aims to highlight the influence of 2D material surfaces and the properties that arise due to their 2D structure. Using recent (within the last few years) examples of biosensors and biomedical applications, we emphasize the important role of 2D materials in advancing developments and research for biosensing and healthcare. © The Royal Society of Chemistry.
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Selective stamping of laser scribed rGO nanofilms: From sensing to multiple applications
Giacomelli C., Álvarez-Diduk R., Testolin A., Merkoçi A. 2D Materials; 7 (2, 024006) 2020. 10.1088/2053-1583/ab68a7. IF: 7.140
A rapid low-cost technology to produce highly conductive laser-scribed reduced-graphene oxide (rGO) thin films on flexible substrates is developed. Isolated rGO films, up to 30 nm thick and with a conductivity of 102 S m-1 are produced at room temperature in a three-step process: filtering the graphene oxide (GO) solution through nitrocellulose membranes, reduction of GO surface using a DVD-burner laser and solvent-free transfer of the resulting rGO pattern onto new substrates via pressure-based mechanism. The loss of density in the reduced part produces an increase in the thickness enabling the transfer of rGO only. The rGO is characterized with several analytical techniques, and its reduction degree, thickness, morphology, electrochemical and electromechanical properties are investigated and optimized. The validation of the technology is tested using a wide variety of substrates, and its applicability as a sensing platform for dopamine detection and back electrode in an electroluminescent lamp is demonstrated, opening the venue for a plethora of other new applications. © 2020 IOP Publishing Ltd.
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Toward Nanotechnology-Enabled Approaches against the COVID-19 Pandemic
Weiss C., Carriere M., Fusco L., Fusco L., Capua I., Regla-Nava J.A., Pasquali M., Pasquali M., Pasquali M., Scott J.A., Vitale F., Vitale F., Unal M.A., Mattevi C., Bedognetti D., Merkoçi A., Merkoçi A., Tasciotti E., Tasciotti E., Yilmazer A., Yilmazer A., Gogotsi Y., Stellacci F., Delogu L.G. ACS Nano; 14 (6): 6383 - 6406. 2020. 10.1021/acsnano.0c03697. IF: 14.588
The COVID-19 outbreak has fueled a global demand for effective diagnosis and treatment as well as mitigation of the spread of infection, all through large-scale approaches such as specific alternative antiviral methods and classical disinfection protocols. Based on an abundance of engineered materials identifiable by their useful physicochemical properties through versatile chemical functionalization, nanotechnology offers a number of approaches to cope with this emergency. Here, through a multidisciplinary Perspective encompassing diverse fields such as virology, biology, medicine, engineering, chemistry, materials science, and computational science, we outline how nanotechnology-based strategies can support the fight against COVID-19, as well as infectious diseases in general, including future pandemics. Considering what we know so far about the life cycle of the virus, we envision key steps where nanotechnology could counter the disease. First, nanoparticles (NPs) can offer alternative methods to classical disinfection protocols used in healthcare settings, thanks to their intrinsic antipathogenic properties and/or their ability to inactivate viruses, bacteria, fungi, or yeasts either photothermally or via photocatalysis-induced reactive oxygen species (ROS) generation. Nanotechnology tools to inactivate SARS-CoV-2 in patients could also be explored. In this case, nanomaterials could be used to deliver drugs to the pulmonary system to inhibit interaction between angiotensin-converting enzyme 2 (ACE2) receptors and viral S protein. Moreover, the concept of "nanoimmunity by design"can help us to design materials for immune modulation, either stimulating or suppressing the immune response, which would find applications in the context of vaccine development for SARS-CoV-2 or in counteracting the cytokine storm, respectively. In addition to disease prevention and therapeutic potential, nanotechnology has important roles in diagnostics, with potential to support the development of simple, fast, and cost-effective nanotechnology-based assays to monitor the presence of SARS-CoV-2 and related biomarkers. In summary, nanotechnology is critical in counteracting COVID-19 and will be vital when preparing for future pandemics. © 2020 American Chemical Society.
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Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays
Parolo C., Sena-Torralba A., Bergua J.F., Calucho E., Fuentes-Chust C., Hu L., Rivas L., Álvarez-Diduk R., Nguyen E.P., Cinti S., Quesada-González D., Merkoçi A. Nature Protocols; 15 (12): 3788 - 3816. 2020. 10.1038/s41596-020-0357-x. IF: 10.419
Lateral-flow assays (LFAs) are quick, simple and cheap assays to analyze various samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample throughout a series of sequential pads, each with different functionalities aiming to generate a signal to indicate the absence/presence (and, in some cases, the concentration) of the analyte of interest. To have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this tutorial, we provide the readers with: (i) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, (ii) a roadmap for optimal LFA development independent of the specific application, (iii) a step-by-step example procedure for the assembly and operation of an LF strip for the detection of human IgG and (iv) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs. By changing only the receptors, the provided example procedure can easily be adapted for cost-efficient detection of a broad variety of targets. © 2020, The Author(s), under exclusive licence to Springer Nature Limited.
2019
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A nitrocellulose paper strip for fluorometric determination of bisphenol A using molecularly imprinted nanoparticles
Üzek R., Sari E., Şenel S., Denizli A., Merkoçi A. Microchimica Acta; 186 (4, 218) 2019. 10.1007/s00604-019-3323-y. IF: 5.479
The authors describe a test stripe for fluorometric determination of the endocrine disruptor bisphenol A (BPA). Graphene quantum dots (GQDs) were immobilized on molecularly imprinted nanoparticles which then were placed on nitrocellulose paper. The GQDs display blue fluorescence (with excitation/emission peaks at 350/440 nm) which is reduced in the presence of BPA. The test stripe has a 43.9 ± 0.8 μg·L −1 limit of detection in case of water samples. The stripe was applied to the determination of BPA in (spiked) tap water and sea water, and the LODs were found to be 1.8 ± 0.2 μg·L −1 and 4.2 ± 0.5 μg·L −1 , respectively. Structural analogs of BPA, such as aminophenol, phenol, hydroquinone and naphthol were found not to interfere. [Figure not available: see fulltext.]. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature.
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Disposable Sensors in Diagnostics, Food, and Environmental Monitoring
Dincer C., Bruch R., Costa-Rama E., Fernández-Abedul M.T., Merkoçi A., Manz A., Urban G.A., Güder F. Advanced Materials; 31 (30, 1806739) 2019. 10.1002/adma.201806739. IF: 25.809
Disposable sensors are low-cost and easy-to-use sensing devices intended for short-term or rapid single-point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource-limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo- and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low-cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Electrochemical detection of plant virus using gold nanoparticle-modified electrodes
Khater M., de la Escosura-Muñiz A., Quesada-González D., Merkoçi A. Analytica Chimica Acta; 1046: 123 - 131. 2019. 10.1016/j.aca.2018.09.031. IF: 5.256
Tristeza is one of the destructive diseases of citrus causing by citrus tristeza virus (CTV). Historically, CTV has been associated with serious outbreaks of quick decline of citrus, therefore CTV monitoring is important aspect for avoiding such re-emerging epidemics, which would threat citrus production through the world. In this context, we have designed for the first time a label-free impedimetric biosensor for the detection of nucleic acid of CTV. The sensing platform based on a screen-printed carbon electrode (SPCE) was modified by electrodeposited gold nanoparticles (AuNPs), which allowed to efficiently immobilizing thiolated ssDNA probes as well to enhance the electrode conductivity. The growth of AuNPs was optimized and characterized using scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). We investigated the behavior of thiolated ssDNA probe layer and its hybridization with target DNA onto AuNP surfaces by EIS measurements in Fe(CN 6 ) 4- /Fe(CN 6 ) 3- red-ox system. The main sensor design aspects such as AuNPs size, probe DNA concentration and immobilization time together with DNA hybridization time were optimized so as to achieve the best performance. Impedance values of DNA hybridization increased with Citrus tristeza-related synthetic DNA concentration, showing a logarithmic relation in the range of 0.1–10 μM. The results also indicate that the biosensor was able to selectively detect CTV nucleic acids in the presence of other non-specific DNAs. Moreover, we have demonstrated the good performance of the system in a real plant sample matrix. In addition, the sensor reproducibility enhanced after the hybridization onto MCH/poly (AT) thiolated DNA probes which was confirmed by intra- and inter-day variability assays. © 2018 Elsevier B.V.
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Fully printed one-step biosensing device using graphene/AuNPs composite
Nagar B., Balsells M., de la Escosura-Muñiz A., Gomez-Romero P., Merkoçi A. Biosensors and Bioelectronics; 129: 238 - 244. 2019. 10.1016/j.bios.2018.09.073. IF: 9.518
Driven by the growing need of simple, cost efficient and flexible sensing systems, we have designed here a fully printed Reduced Graphene Oxide (rGO) based impedimetric sensor for one step sensing of DNA. The DNA sensor was fabricated by stamping of layered rGO and rGO/gold nanoparticles/single stranded DNA (rGO/AuNPs/ssDNA) composites over PET substrates using wax-printing technique. rGO works as an excellent working electrode, while the AuNPs create a suitable environment for ssDNA immobilization. Counter and reference electrodes were previously screen-printed on the plastic substrate, making thus a compact and highly integrated sensing platform. The change in electron transfer resistance after hybridization with a target ssDNA specific of Coxsackie B3 virus was monitored using electrochemical impedance spectroscopy (EIS), finding a linear response in the range of concentrations 0.01–20 µM. The novel, simple and straightforward one-step printing process for fabrication of a biosensing device developed keeps in mind the growing need of large scale device manufacturing. The successful proof-of-concept for the detection of DNA hybridization can be extended to other affinity biosensors, taking advantage of the integration of the bioreceptor on the sensor surface. Such ready-to-use biosensor would lead to a one-step electrochemical detection. © 2018 Elsevier B.V.
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Graphene Oxide as an Optical Biosensing Platform: A Progress Report
Morales-Narváez E., Merkoçi A. Advanced Materials; 31 (6, 1805043) 2019. 10.1002/adma.201805043. IF: 25.809
A few years ago, crucial graphene oxide (GO) features such as the carbon/oxygen ratio, number of layers, and lateral size were scarcely investigated and, thus, their impact on the overall optical biosensing performance was almost unknown. Nowadays valuable insights about these features are well documented in the literature, whereas others remain controversial. Moreover, most of the biosensing systems based on GO were amenable to operating as colloidal suspensions. Currently, the literature reports conceptually new approaches obviating the need of GO colloidal suspensions, enabling the integration of GO onto a solid phase and leading to their application in new biosensing devices. Furthermore, most GO-based biosensing devices exploit photoluminescent signals. However, further progress is also achieved in powerful label-free optical techniques exploiting GO in biosensing, particularly using optical fibers, surface plasmon resonance, and surface enhanced Raman scattering. Herein, a critical overview on these topics is offered, highlighting the key role of the physicochemical properties of GO. New challenges and opportunities in this exciting field are also highlighted. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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In Situ Plant Virus Nucleic Acid Isothermal Amplification Detection on Gold Nanoparticle-Modified Electrodes
Khater M., Escosura-Muñiz A.D.L., Altet L., Merkoçi A. Analytical Chemistry; 91 (7): 4790 - 4796. 2019. 10.1021/acs.analchem.9b00340. IF: 6.350
Solid-phase isothermal recombinase polymerase amplification (RPA) offers many benefits over the standard RPA in homogeneous phase in terms of sensitivity, portability, and versatility. However, RPA devices reported to date are limited by the need for heating sources to reach sensitive detection. With the aim of overcoming such limitation, we propose here a label-free highly integrated in situ RPA amplification/detection approach at room temperature that takes advantage of the high sensitivity offered by gold nanoparticle (AuNP)-modified sensing substrates and electrochemical impedance spectroscopic (EIS) detection. Plant disease (Citrus tristeza virus (CTV)) diagnostics was selected as a relevant target for demonstration of the proof-of-concept. RPA assay for amplification of the P20 gene (387-bp) characteristic of CTV was first designed/optimized and tested by standard gel electrophoresis analysis. The optimized RPA conditions were then transferred to the AuNP-modified electrode surface, previously modified with a thiolated forward primer. The in situ-amplified CTV target was investigated by EIS in a Fe(CN 6 ) 4- /Fe(CN 6 ) 3- red-ox system, being able to quantitatively detect 1000 fg μL -1 of nucleic acid. High selectivity against nonspecific gene sequences characteristic of potential interfering species such as Citrus psorosis virus (CPsV) and Citrus caxicia viroid (CCaV) was demonstrated. Good reproducibility (RSD of 8%) and long-term stability (up to 3 weeks) of the system were also obtained. Overall, with regard to sensitivity, cost, and portability, our approach exhibits better performance than RPA in homogeneous phase, also without the need of heating sources required in other solid-phase approaches. © 2019 American Chemical Society.
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Iridium oxide (IV) nanoparticle-based electrocatalytic detection of PBDE
Quesada-González D., Baiocco A., Martos A.A., de la Escosura-Muñiz A., Palleschi G., Merkoçi A. Biosensors and Bioelectronics; 127: 150 - 154. 2019. 10.1016/j.bios.2018.11.050. IF: 9.518
Polybrominated diphenyl ethers (PBDEs) are a type of flame retardants which are currently banned in EU and USA due their hazardousness for humans and mammals. However, these compounds were highly used during more than 30 years and still persist in the environment since they are resistant to degradation. Herein we present a biosensor for the detection of PBDEs using screen printed carbon electrodes (SPCEs) based on the electrochemical monitoring of water oxidation reaction (WOR) catalyzed by iridium oxide (IV) nanoparticles (IrO 2 NPs). Our assay shows a limit of detection of 21.5 ppb of PBDE in distilled water. We believe that such an IrO 2 NPs-based electrocatalytic sensing system can lead to a rapid, sensitive, low cost and miniaturizable device for the detection of PBDEs. © 2018 Elsevier B.V.
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Iridium oxide (IV) nanoparticle-based lateral flow immunoassay
Quesada-González D., Sena-Torralba A., Wicaksono W.P., de la Escosura-Muñiz A., Ivandini T.A., Merkoçi A. Biosensors and Bioelectronics; 132: 132 - 135. 2019. 10.1016/j.bios.2019.02.049. IF: 9.518
Lateral flow biosensors are paper-based devices that allow the detection of different types of analytes with quickness, robustness and selectivity, without leaving behind paper sensors benefits as low-cost, recyclability and sustainability. Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein. These nanoparticles can be easily prepared and conjugated with biomarkers. Their dark blue color gives a high contrast against the white background of the strips being in this way excellent labels. © 2019 Elsevier B.V.
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Nanomaterial-based Sensors for the Study of DNA Interaction with Drugs
De la Cruz Morales K., Alarcón-Angeles G., Merkoçi A. Electroanalysis; 31 (10): 1845 - 1867. 2019. 10.1002/elan.201900286. IF: 2.691
The interaction of drugs with DNA has been searched thoroughly giving rise to an endless number of findings of undoubted importance, such as a prompt alert to harmful substances, ability to explain most of the biological mechanisms, or provision of important clues in targeted development of novel chemotherapeutics. The existence of some drugs that induce oxidative damage is an increasing point of concern as they can cause cellular death, aging, and are closely related to the development of many diseases. Because of a direct correlation between the response, strength/ nature of the interaction and the pharmaceutical action of DNA-targeted drugs, the electrochemical analysis is based on the signals of DNA before and after the interaction with the DNA-targeted drug. Nowadays, nanoscale materials are used extensively for offering fascinating characteristics that can be used in designing new strategies for drug-DNA interaction detection. This work presents a review of nanomaterials (NMs) for the study of drug-nucleic acid interaction. We summarize types of drug-DNA interactions, electroanalytical techniques for evidencing these interactions and quantification of drug and/or DNA monitoring. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Optical-Based (Bio) Sensing Systems Using Magnetic Nanoparticles
Üzek, R., Sari, E., Merkoçi Magnetochemistry; 5 (4): 59. 2019. 10.3390/magnetochemistry5040059. IF: 1.947
In recent years, various reports related to sensing application research have suggested that combining the synergistic impacts of optical, electrical or magnetic properties in a single technique can lead to a new multitasking platform. Owing to their unique features of the magnetic moment, biocompatibility, ease of surface modification, chemical stability, high surface area, high mass transference, magnetic nanoparticles have found a wide range of applications in various fields, especially in sensing systems. The present review is comprehensive information about magnetic nanoparticles utilized in the optical sensing platform, broadly categorized into four types: surface plasmon resonance (SPR), surface-enhanced Raman spectroscopy (SERS), fluorescence spectroscopy and near-infrared spectroscopy and imaging (NIRS) that are commonly used in various (bio) analytical applications. The review also includes some conclusions on the state of the art in this field and future aspects.
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Paper Based Photoluminescent Sensing Platform with Recognition Sites for Tributyltin
Sari E., Üzek R., Merkoçi A. ACS Sensors; 4 (3): 645 - 653. 2019. 10.1021/acssensors.8b01396. IF: 6.944
In this study, a novel photoluminescence material for the detection of tributyltin (TBT) was developed by using a paper-based nanocomposite system. For this purpose, molecularly imprinted polymeric nanoparticles (MIN) were synthesized with mini-emulsion polymerization technique. Graphene quantum dots obtained by the hydrothermal pyrolysis were immobilized to the nanoparticle surface via EDC-NHS coupling. The fabrication of sensing platform for TBT can be divided into two steps that are the preparation of nanocomposite and the applying the nanocomposite onto nitrocellulose membrane. The selectivity constant and association kinetics were calculated to analyze the interaction of TBT with immobilized MINs. The results proved that the developed nanosensor is promising for the determination of TBT with high selectivity and sensitivity reaching a detection limit of 0.23 ppt in seawater. This novel photoluminescent nanosensor has the potential to pave the way for further studies and applications. © 2019 American Chemical Society.
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Production and printing of graphene oxide foam ink for electrocatalytic applications
Baptista-Pires L., de la Escosura-Muñiz A., Balsells M., Zuaznabar-Gardona J.C., Merkoçi A. Electrochemistry Communications; 98: 6 - 9. 2019. 10.1016/j.elecom.2018.11.001. IF: 4.197
A graphene-based ink printed as a foam-like structure with open pores is reported. The production of the ink is easier and faster than using existing methods and the obtained product is stable in water suspension. Electrocatalytic applications of 3D structured electrodes printed onto plastic substrates were explored. © 2018 Elsevier B.V.
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Signal enhancement on gold nanoparticle-based lateral flow tests using cellulose nanofibers
Quesada-González D., Stefani C., González I., de la Escosura-Muñiz A., Domingo N., Mutjé P., Merkoçi A. Biosensors and Bioelectronics; 141 (111407) 2019. 10.1016/j.bios.2019.111407. IF: 9.518
Lateral flow paper-based biosensors merge as powerful tools in point-of-care diagnostics since they are cheap, portable, robust, selective, fast and easy to use. However, the sensitivity of this type of biosensors is not always as high as required, often not permitting a clear quantification. To improve the colorimetric response of standard lateral flow strips (LFs), we have applied a new enhancement strategy that increases the sensitivity of LFs based on the use of cellulose nanofibers (CNF). CNF penetrate inside the pores of LFs nitrocellulose paper, compacting the pore size only in the test line, particularly near the surface of the strip. This modification retains the bioreceptors (antibodies) close to the surface of the strips, and thus further increasing the density of selectively attached gold nanoparticles (AuNPs) in the top part of the membrane, in the test line area, only when the sample is positive. This effect boosts in average a 36.6% the sensitivity of the LFs. The optical measurements of the LFs were carried out with a mobile phone camera whose imaging resolution was improved by attaching microscopic lens on the camera objective. The characterization of CNF into paper and their effect was analyzed using atomic force microscope (AFM) and scanning electron microscope (SEM) imaging techniques. © 2019 Elsevier B.V.
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Smart Chip for Visual Detection of Bacteria Using the Electrochromic Properties of Polyaniline
Ranjbar S., Nejad M.A.F., Parolo C., Shahrokhian S., Merkoçi A. Analytical Chemistry; 91 (23): 14960 - 14966. 2019. 10.1021/acs.analchem.9b03407. IF: 6.350
Finding fast and reliable ways to detect pathogenic bacteria is crucial for addressing serious public health issues in clinical, environmental, and food settings. Here, we present a novel assay based on the conversion of an electrochemical signal into a more convenient optical readout for the visual detection of Escherichia coli. Electropolymerizing polyaniline (PANI) on an indium tin oxide screen-printed electrode (ITO SPE), we achieved not only the desired electrochromic behavior but also a convenient way to modify the electrode surface with antibodies (taking advantage of the many amine groups of PANI). Applying a constant potential to the PANI-modified ITO SPE induces a change in their oxidation state, which in turn generates a color change on the electrode surface. The presence of E. coli on the electrode surface increases the resistance in the circuit affecting the PANI oxidation states, producing a different electrochromic response. Using this electrochromic sensor, we could measure concentrations of E. coli spanning 4 orders of magnitude with a limit of detection of 102 colony forming unit per 1 mL (CFU mL-1) by the naked eye and 101 CFU mL-1 using ImageJ software. In this work we show that merging the sensitivity of electrochemistry with the user-friendliness of an optical readout can generate a new and powerful class of biosensors, with potentially unlimited applications in a variety of fields. Copyright © 2019 American Chemical Society.
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Validity of a single antibody-based lateral flow immunoassay depending on graphene oxide for highly sensitive determination of E. coli O157:H7 in minced beef and river water
Hassan A.H.A., Bergua J.F., Morales-Narváez E., Mekoçi A. Food Chemistry; 297 (124965) 2019. 10.1016/j.foodchem.2019.124965. IF: 5.399
Considering the health risks of E. coli O157:H7 presence in food and water, an affordable and highly sensitive detection method is crucial. Herein, we report the first use of a single antibody-based fluorescent lateral flow immunoassay (FLFIA) depending on non-radiative energy transfer between graphene oxide and quantum dots for determination of E. coli O157:H7 in beef and river water. FLFIA showed a high sensitivity rate thousand-fold better than the conventional lateral flow (LF). In inoculated minced beef and river water samples, the limits of detection were 178 and 133 CFU g−1 or mL−1, respectively. Besides, it presented a high selectivity in the presence of other possible interfering bacteria. The single antibody approach reduced the assay cost to 60% less than the conventional LF. Alongside, the results could be read by portable LF readers or smartphones. These advantages offer FLFIA as a promising technology for pathogen detection in food and water. © 2019 Elsevier Ltd
2018
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2D Materials-based Platforms for Electroanalysis Applications
Alarcon-Angeles G., Palomar-Pardavé M., Merkoçi A. Electroanalysis; 30 (7): 1271 - 1280. 2018. 10.1002/elan.201800245. IF: 2.851
A new class of nanomaterials called “2D materials” (2DMs) is attracting recently the electrochemical sensing field due to the unique physicochemical properties associated to their chemical structure, formed by ultra-thin layers. In this review, we summarize the recent advances in the electroanalysis area using 2DMs giving first a brief overview on the structure, synthesis and properties of these materials followed by the analysis of their advantages while used in the development of electrochemical sensors. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Architecting Graphene Oxide Rolled-Up Micromotors: A Simple Paper-Based Manufacturing Technology
Baptista-Pires L., Orozco J., Guardia P., Merkoçi A. Small; 14 (3, 1702746) 2018. 10.1002/smll.201702746. IF: 9.598
A graphene oxide rolled-up tube production process is reported using wax-printed membranes for the fabrication of on-demand engineered micromotors at different levels of oxidation, thickness, and lateral dimensions. The resultant graphene oxide rolled-up tubes can show magnetic and catalytic movement within the addition of magnetic nanoparticles or sputtered platinum in the surface of graphene-oxide-modified wax-printed membranes prior to the scrolling process. As a proof of concept, the as-prepared catalytic graphene oxide rolled-up micromotors are successfully exploited for oil removal from water. This micromotor production technology relies on an easy, operator-friendly, fast, and cost-efficient wax-printed paper-based method and may offer a myriad of hybrid devices and applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei/1.
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Bioluminescent nanopaper for rapid screening of toxic substances
Liu J., Morales-Narváez E., Orozco J., Vicent T., Zhong G., Merkoçi A. Nano Research; 11 (1): 114 - 125. 2018. 10.1007/s12274-017-1610-7. IF: 7.994
Environmental pollution is threatening human health and ecosystems as a result of modern agricultural techniques and industrial progress. A simple nanopaper-based platform coupled with luminescent bacteria Aliivibrio fischeri (A. fischeri) as a bio-indicator is presented here, for rapid and sensitive evaluation of contaminant toxicity. When exposed to toxicants, the luminescence inhibition of A. fischeri-decorated bioluminescent nanopaper (BLN) can be quantified and analyzed to classify the toxicity level of a pollutant. The BLN composite was characterized in terms of morphology and functionality. Given the outstanding biocompatibility of nanocellulose for bacterial proliferation, BLN achieved high sensitivity with a low cost and simplified procedure compared to conventional instruments for laboratory use only. The broad applicability of BLN devices to environmental samples was studied in spiked real matrices (lake and sea water), and their potential for direct and in situ toxicity screening was demonstrated. The BLN architecture not only survives but also maintains its function during freezing and recycling processes, endowing the BLN system with competitive advantages as a deliverable, ready-to-use device for large-scale manufacturing. The novel luminescent bacteria-immobilized, nanocelullose-based device shows outstanding abilities for toxicity bioassays of hazardous compounds, bringing new possibilities for cheap and efficient environmental monitoring of potential contamination. © 2018, Tsinghua University Press and Springer-Verlag GmbH Germany.
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Design and Fabrication of Printed Paper-Based Hybrid Micro-Supercapacitor by using Graphene and Redox-Active Electrolyte
Nagar B., Dubal D.P., Pires L., Merkoçi A., Gómez-Romero P. ChemSusChem; 11 (11): 1849 - 1856. 2018. 10.1002/cssc.201800426. IF: 7.411
Inspired by future needs of flexible, simple, and low-cost energy storage devices, smart graphene-based micro-supercapacitors on conventional Xerox paper substrates were developed. The use of redox-active species (iodine redox couple) was explored to further improve the paper device's performance. The device based on printed graphene paper itself already had a remarkable maximum volumetric capacitance of 29.6 mF cm−3 (volume of whole device) at 6.5 mA cm−3. The performance of the hybrid electrode with redox-active potassium iodide at the graphene surface was tested. Remarkably, the hybrid device showed improved volumetric capacitance of 130 mF cm−3. The maximum energy density for a graphene+KI device in H2SO4 electrolyte was estimated to be 0.026 mWh cm−3. Thus, this work offers a new simple, and lightweight micro-supercapacitor based on low-cost printed graphene paper, which will have great applications in portable electronics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Electrochromic Molecular Imprinting Sensor for Visual and Smartphone-Based Detections
Capoferri D., Álvarez-Diduk R., Del Carlo M., Compagnone D., Merkoçi A. Analytical Chemistry; 90 (9): 5850 - 5856. 2018. 10.1021/acs.analchem.8b00389. IF: 6.042
Electrochromic effect and molecularly imprinted technology have been used to develop a sensitive and selective electrochromic sensor. The polymeric matrices obtained using the imprinting technology are robust molecular recognition elements and have the potential to mimic natural recognition entities with very high selectivity. The electrochromic behavior of iridium oxide nanoparticles (IrOx NPs) as physicochemical transducer together with a molecularly imprinted polymer (MIP) as recognition layer resulted in a fast and efficient translation of the detection event. The sensor was fabricated using screen-printing technology with indium tin oxide as a transparent working electrode; IrOx NPs where electrodeposited onto the electrode followed by thermal polymerization of polypyrrole in the presence of the analyte (chlorpyrifos). Two different approaches were used to detect and quantify the pesticide: direct visual detection and smartphone imaging. Application of different oxidation potentials for 10 s resulted in color changes directly related to the concentration of the analyte. For smartphone imaging, at fixed potential, the concentration of the analyte was dependent on the color intensity of the electrode. The electrochromic sensor detects a highly toxic compound (chlorpyrifos) with a 100 fM and 1 mM dynamic range. So far, to the best of our knowledge, this is the first work where an electrochromic MIP sensor uses the electrochromic properties of IrOx to detect a certain analyte with high selectivity and sensitivity. © 2018 American Chemical Society.
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In situ monitoring of PTHLH secretion in neuroblastoma cells cultured onto nanoporous membranes
de la Escosura-Muñiz A., Espinoza-Castañeda M., Chamorro-García A., Rodríguez-Hernández C.J., de Torres C., Merkoçi A. Biosensors and Bioelectronics; 107: 62 - 68. 2018. 10.1016/j.bios.2018.01.064. IF: 8.173
In this work, we propose for the first time the use of anodic aluminum oxide (AAO) nanoporous membranes for in situ monitoring of parathyroid hormone-like hormone (PTHLH) secretion in cultured human cells. The biosensing system is based on the nanochannels blockage upon immunocomplex formation, which is electrically monitored through the voltammetric oxidation of Prussian blue nanoparticles (PBNPs). Models evaluated include a neuroblastoma cell line (SK-N-AS) and immortalized keratinocytes (HaCaT) as a control of high PTHLH production. The effect of total number of seeded cells and incubation time on the secreted PTHLH levels is assessed, finding that secreted PTHLH levels range from approximately 60 to 400 ng/mL. Moreover, our methodology is also applied to analyse PTHLH production following PTHLH gene knockdown upon transient cell transfection with a specific silencing RNA (siRNA). Given that inhibition of PTHLH secretion reduces cell proliferation, survival and invasiveness in a number of tumors, our system provides a powerful tool for the preclinical evaluation of therapies that regulate PTHLH production. This nanoporous membrane – based sensing technology might be useful to monitor the active secretion of other proteins as well, thus contributing to characterize their regulation and function. © 2018 Elsevier B.V.
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Low-Cost Strategy for the Development of a Rapid Electrochemical Assay for Bacteria Detection Based on AuAg Nanoshells
Russo L., Leva Bueno J., Bergua J.F., Costantini M., Giannetto M., Puntes V., De La Escosura-Muñiz A., Merkoçi A. ACS Omega; 3 (12): 18849 - 18856. 2018. 10.1021/acsomega.8b02458.
A low-cost strategy for the simple and rapid detection of bacterial cells in biological matrixes is presented herein. Escherichia coli and Salmonella typhimurium were chosen as model bacteria for the development of an electrochemical assay based on hollow AuAg nanoshells (NSs). By taking advantage of their electrocatalytic properties for the in situ generation of the electrochemical signal without the need of any other kind of reagent, substrate, or redox enzyme, high sensitivities (down to 102 CFU/mL) were achieved. Moreover, the recognition and discrimination of the model bacterial cells in the sample matrix was possible by relying solely on nonspecific affinity interactions between their cell walls and AuAg NSs surface, avoiding the use of expensive and fragile biological receptor. Compared to traditional, laboratory-based analytical tests available, this assay provides a promising proof-of-concept alternative that allows to obtain good sensitivities and selectivity in very short times in addition to the low cost. © 2018 American Chemical Society.
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Microorganism-decorated nanocellulose for efficient diuron removal
Liu J., Morales-Narváez E., Vicent T., Merkoçi A., Zhong G.-H. Chemical Engineering Journal; 354: 1083 - 1091. 2018. 10.1016/j.cej.2018.08.035. IF: 6.735
The environmental impacts of diuron have generated growing interest in remediation methods to prevent the potential threat of diuron to ecosystem integrity and human beings. Here, a simple and effective nanocellulose-based biocomposite coupled with Arthrobacter globiformis D47 as a herbicide degrader is presented for the rapid elimination of diuron. First, bacterium D47 was immobilized on the fiber networks of the nanocellulose, forming a bacteria-decorated nanocellulose (BDN) that outperformed direct utilization of bacterial suspensions for diuron decomposition. More importantly, the advantageous features of BDN could remarkably broaden its applicability since the bio-hybrid material rapidly degraded diuron and its major metabolite 3,4-dichloroaniline at low concentrations (1–10 mg L−1). In addition, the morphology of BDN revealed the excellent biocompatibility of nanocellulose as cell scaffolding for bacterial proliferation. Then, the adsorption capacity of the nanocellulose and the enzymatic metabolism of the bacteria were validated as a joint mechanism of the BDN biocomposites in the removal of diuron. In addition, the wide applicability of BDN was further verified by the degradation of diuron in environmental matrices and other phenylurea herbicide targets. Therefore, the novel microorganism-immobilized nanocellulose composites provide a promising alternative material combining functional microorganisms with emerging nanomaterials, which may facilitate the bioremediation of organic xenobiotic pollution in complex environments. © 2018 Elsevier B.V.
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Nanomaterial-based devices for point-of-care diagnostic applications
Quesada-González D., Merkoçi A. Chemical Society Reviews; 47 (13): 4697 - 4709. 2018. 10.1039/c7cs00837f. IF: 40.182
In this review, we have discussed the capabilities of nanomaterials for point-of-care (PoC) diagnostics and explained how these materials can help to strengthen, miniaturize and improve the quality of diagnostic devices. Since the optical, electrochemical and other physical properties of nanomaterials are dictated by their composition, size and shape, these factors are critical in the design and function of nanomaterial-based PoC diagnostics. © 2018 The Royal Society of Chemistry.
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Photoluminescent lateral flow based on non-radiative energy transfer for protein detection in human serum
Zamora-Gálvez A., Morales-Narváez E., Romero J., Merkoçi A. Biosensors and Bioelectronics; 100: 208 - 213. 2018. 10.1016/j.bios.2017.09.013. IF: 8.173
A new paper-based lateral flow immunoassay configuration was engineered and investigated. The assay is intended for the detection of a model protein in human serum, that is, human immunoglobulin G, with the aim to demonstrate a virtually universal protein detection platform. Once the sample is added in the strip, the analyte is selectively captured by antibody-decorated silica beads (Ab-SiO2) onto the conjugate pad and the sample flows by capillarity throughout the strip until reaching the test line, where a sandwich-like immunocomplex takes place due to the presence of antibody-functionalized QDs (Ab-QDs) onto the test line. Eventually, GO is added as a revealing agent and the photoluminescence of those sites protected by the complex Ab-SiO2/Antigen/Ab-QDs will not be quenched, whereas those photoluminescent sites directly exposed are expected to be quenched by GO, including the control line, made of bare QDs, reporting that the assay occurred successfully. Hence, the photoluminescence of the test line is modulated by the formation of sandwich-like immunocomplexes. The proposed device achieves a limit of detection (LOD) of 1.35 ng mL−1 in standard buffer, which is lower when compared with conventional lateral flow technology reported by gold nanoparticles, including other amplification strategies. Moreover, the resulting device was proven useful in human serum analysis, achieving a LOD of 6.30 ng mL−1 in this complex matrix. This low-cost disposable and easy-to-use device will prove valuable for portable and automated diagnostics applications, and can be easily transferred to other analytes such as clinically relevant protein biomarkers. © 2017
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Screen-Printed Electroluminescent Lamp Modified with Graphene Oxide as a Sensing Device
Yakoh A., Álvarez-Diduk R., Chailapakul O., Merkoçi A. ACS Applied Materials and Interfaces; 10 (24): 20775 - 20782. 2018. 10.1021/acsami.8b04883. IF: 8.097
A screen-printed electroluminescent display with different sensing capabilities is presented. The sensing principle is based on the direct relationship between the light intensity of the lamp and the conductivity of the external layers. The proposed device is able to detect the ionic concentration of any conductive species. Using both top and bottom emission architectures, for the first time, a humidity sensor based on electroluminescent display functionalized by a graphene oxide nanocomposite is introduced. In this regard, just by coupling the display to a smartphone camera sensor, its potential was expanded for automatically monitoring human respiration in real time. Besides, the research includes a responsive display in which the light is spatially turned on in response to pencil drawing or any other conductive media. The above mentioned features together with the easiness of manufacturing and cost-effectiveness of this electroluminescent display can open up great opportunities to exploit it in sensing applications and point-of-care diagnosis. Copyright © 2018 American Chemical Society.
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Time- and Size-Resolved Plasmonic Evolution with nm Resolution of Galvanic Replacement Reaction in AuAg Nanoshells Synthesis
Russo L., Merkoçi F., Patarroyo J., Piella J., Merkoçi A., Bastús N.G., Puntes V. Chemistry of Materials; 30 (15): 5098 - 5107. 2018. 10.1021/acs.chemmater.8b01488. IF: 9.890
The rational design of advanced nanomaterials with enhanced optical properties can be reached only with the profound thermodynamic and kinetic understanding of their synthetic processes. In this work, the synthesis of monodisperse AuAg nanoshells with thin shells and large voids is achieved through the development of a highly reproducible and robust methodology based on the galvanic replacement reaction. This is obtained thanks to the systematic identification of the role played by the different synthetic parameters involved in the process (such as surfactants, co-oxidizers, complexing agents, time, and temperature), providing an unprecedented control over the material's morphological and optical properties. Thus, the time- and size-resolved evolution of AuAg nanoshells surface plasmon resonance band is described for 15, 30, 60, 80, 100, and 150 nm-sized particles spanning almost through the entire visible spectrum. Its analysis reveals a four-phase mechanism coherent with the material's morphological transformation. Simulations based on Mie's theory confirm the observed optical behavior in AuAg nanoshells formation and provide insights into the influence of the Au/Ag ratio on their plasmonic properties. The high degree of morphological control provided by this methodology represents a transferable and scalable strategy for the development of advanced-generation plasmonic nanomaterials. © 2018 American Chemical Society.
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Tunable electrochemistry of gold-silver alloy nanoshells
Russo L., Puntes V., Merkoçi A. Nano Research; 11 (12): 6336 - 6345. 2018. 10.1007/s12274-018-2157-y. IF: 7.994
The widespread and increasing interest in enhancing biosensing technologies by increasing their sensitivities and lowering their costs has led to the exploration and application of complex nanomaterials as signal transducers and enhancers. In this work, the electrochemical properties of monodispersed AuAg alloy nanoshells (NSs) with finely tunable morphology, composition, and size are studied to assess their potential as electroactive labels. The controlled corrosion of their silver content, caused by the oxidizing character of dissolved oxygen and chlorides of the electrolyte, allows the generation of a reproducible electrochemical signal that is easily measurable through voltammetric techniques. Remarkably, the underpotential deposition of dissolved Ag+ catalyzed on AuAg NS surfaces is observed and its dependence on the nanoparticle morphology, size, and elemental composition is studied, revealing a strong correlation between the relative amounts of the two metals. The highest catalytic activity is found at Au/Ag ratios higher than ≈ 10, showing how the synergy between both metals is necessary to trigger the enhancement of Ag+ reduction. The ability of AuAg NSs to generate an electrocatalytic current without the need for any strong acid makes them an extremely promising material for biosensing applications. [Figure not available: see fulltext.]. © 2018, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.
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Uranium (VI) detection in groundwater using a gold nanoparticle/paper-based lateral flow device
Quesada-González D., Jairo G.A., Blake R.C., II, Blake D.A., Merkoçi A. Scientific Reports; 8 (1, 16157) 2018. 10.1038/s41598-018-34610-5. IF: 4.122
The contamination in groundwater due to the presence of uranium is nowadays a subject of concern due to the severe health problems associated with renal failure, genotoxicity and cancer. The standard methods to detect uranium require time-consuming processes and expensive non-portable equipment, so these measurements are rarely performed in-field, which increases the time until water samples are analysed. Furthermore, the few portable methods available do not allow quantitative analysis and the detection limit is often not low enough to reach the recommendations for drinking water (30 ppb or 126 nM of uranium). For the first time, we propose a portable, fast, inexpensive and sensitive paper-based biosensor able to detect in situ U(VI) in water samples: U(VI) selective gold nanoparticle-based lateral flow strips. Antibody-coated gold nanoparticles are used as labels in the proposed lateral flow system because of their biocompatibility; in addition, these nanoparticles provide high sensitivity due to their intense plasmonic effect. The antibody used in the assay recognizes soluble U(VI) complexed to the chelator, 2,9-dicarboxyl-1,10-phenanthroline (DCP). Because of the small size of the U(VI)-DCP complex, this assay employs a competitive format that reaches a limit of detection of 36.38 nM, lower than the action level (126 nM) established by the World Health Organization and the U.S. Environmental Protection Agency for drinking waters. © 2018, The Author(s).
2017
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Biosensors for plant pathogen detection
Khater M., de la Escosura-Muñiz A., Merkoçi A. Biosensors and Bioelectronics; 93: 72 - 86. 2017. 10.1016/j.bios.2016.09.091. IF: 7.780
Infectious plant diseases are caused by pathogenic microorganisms such as fungi, bacteria, viruses, viroids, phytoplasma and nematodes. Worldwide, plant pathogen infections are among main factors limiting crop productivity and increasing economic losses. Plant pathogen detection is important as first step to manage a plant disease in greenhouses, field conditions and at the country boarders. Current immunological techniques used to detect pathogens in plant include enzyme-linked immunosorbent assays (ELISA) and direct tissue blot immunoassays (DTBIA). DNA-based techniques such as polymerase chain reaction (PCR), real time PCR (RT-PCR) and dot blot hybridization have also been proposed for pathogen identification and detection. However these methodologies are time-consuming and require complex instruments, being not suitable for in-situ analysis. Consequently, there is strong interest for developing new biosensing systems for early detection of plant diseases with high sensitivity and specificity at the point-of-care. In this context, we revise here the recent advancement in the development of advantageous biosensing systems for plant pathogen detection based on both antibody and DNA receptors. The use of different nanomaterials such as nanochannels and metallic nanoparticles for the development of innovative and sensitive biosensing systems for the detection of pathogens (i.e. bacteria and viruses) at the point-of-care is also shown. Plastic and paper-based platforms have been used for this purpose, offering cheap and easy-to-use really integrated sensing systems for rapid on-site detection. Beside devices developed at research and development level a brief revision of commercially available kits is also included in this review. © 2016 Elsevier B.V.
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Electrochemically reduced graphene and iridium oxide nanoparticles for inhibition-based angiotensin-converting enzyme inhibitor detection
Kurbanoglu S., Rivas L., Ozkan S.A., Merkoçi A. Biosensors and Bioelectronics; 88: 122 - 129. 2017. 10.1016/j.bios.2016.07.109. IF: 7.780
In this work, a novel biosensor based on electrochemically reduced graphene oxide and iridium oxide nanoparticles for the detection of angiotensin-converting enzyme inhibitor drug, captopril, is presented. For the preparation of the biosensor, tyrosinase is immobilized onto screen printed electrode by using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-Hydroxysuccinimide coupling reagents, in electrochemically reduced graphene oxide and iridium oxide nanoparticles matrix. Biosensor response is characterized towards catechol, in terms of graphene oxide concentration, number of cycles to reduce graphene oxide, volume of iridium oxide nanoparticles and tyrosinase solution. The designed biosensor is used to inhibit tyrosinase activity by Captopril, which is generally used to treat congestive heart failure. It is an angiotensin-converting enzyme inhibitor that operates via chelating copper at the active site of tyrosinase and thioquinone formation. The captopril detections using both inhibition ways are very sensitive with low limits of detection: 0.019 µM and 0.008 µM for chelating copper at the active site of tyrosinase and thioquinone formation, respectively. The proposed methods have been successfully applied in captopril determination in spiked human serum and pharmaceutical dosage forms with acceptable recovery values. © 2016 Elsevier B.V.
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Graphene Oxide-Poly(dimethylsiloxane)-Based Lab-on-a-Chip Platform for Heavy-Metals Preconcentration and Electrochemical Detection
Chałupniak A., Merkoçi A. ACS Applied Materials and Interfaces; 9 (51): 44766 - 44775. 2017. 10.1021/acsami.7b12368. IF: 7.504
Herein, we present the application of a novel graphene oxide-poly(dimethylsiloxane) (GO-PDMS) composite in reversible adsorption/desorption, including detection of heavy metals. GO-PDMS was fabricated by simple blending of GO with silicon monomer in the presence of tetrahydrofuran, followed by polymerization initiated upon the addition of curing agent. We found GO concentration, curing agent concentration, pH, and contact time among the most important factors affecting the adsorption of Pb(II) used as a model heavy metal. The mechanism of adsorption is based on surface complexation, where oxygen active groups of negative charge can bind with bivalent metal ions Me(II). To demonstrate a practical application of this material, we fabricated microfluidic lab-on-a-chip platform for heavy-metals preconcentration and detection. This device consists of a screen-printed carbon electrode, a PDMS chip, and a GO-PDMS chip. The use of GO-PDMS preconcentration platform significantly improves the sensitivity of electrochemical detection of heavy metals (an increase of current up to 30× was observed), without the need of modifying electrodes or special reagents addition. Therefore, samples being so far below the limit of detection (0.5 ppb) were successfully detected. This approach is compatible also with real samples (seawater) as ionic strength was found as indifferent for the adsorption process. To the best of our knowledge, GO-PDMS was used for the first time in sensing application. Moreover, due to mechanical resistance and outstanding durability, it can be used multiple times unlike other GO-based platforms for heavy-metals adsorption. © 2017 American Chemical Society.
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Graphene-Based Biosensors: Going Simple
Morales-Narváez E., Baptista-Pires L., Zamora-Gálvez A., Merkoçi A. Advanced Materials; 29 (7, 1604905) 2017. 10.1002/adma.201604905. IF: 19.791
The main properties of graphene derivatives facilitating optical and electrical biosensing platforms are discussed, along with how the integration of graphene derivatives, plastic, and paper can lead to innovative devices in order to simplify biosensing technology and manufacture easy-to-use, yet powerful electrical or optical biosensors. Some crucial issues to be overcome in order to bring graphene-based biosensors to the market are also underscored. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Graphene-based hybrid for enantioselective sensing applications
Zor E., Morales-Narváez E., Alpaydin S., Bingol H., Ersoz M., Merkoçi A. Biosensors and Bioelectronics; 87: 410 - 416. 2017. 10.1016/j.bios.2016.08.074. IF: 7.780
Chirality is a major field of research of chemical biology and is essential in pharmacology. Accordingly, approaches for distinguishing between different chiral forms of a compound are of great interest. We report on an efficient and generic enantioselective sensor that is achieved by coupling reduced graphene oxide with γ-cyclodextrin (rGO/γ-CD). The enantioselective sensing capability of the resulting structure was operated in both electrical and optical mode for of tryptophan enantiomers (D-/L-Trp). In this sense, voltammetric and photoluminescence measurements were conducted and the experimental results were compared to molecular docking method. We gain insight into the occurring recognition mechanism with selectivity toward D- and L-Trp as shown in voltammetric, photoluminescence and molecular docking responses. As an enantioselective solid phase on an electrochemical transducer, thanks to the different dimensional interaction of enantiomers with hybrid material, a discrepancy occurs in the Gibbs free energy leading to a difference in oxidation peak potential as observed in electrochemical measurements. The optical sensing principle is based on the energy transfer phenomenon that occurs between photoexcited D-/L-Trp enantiomers and rGO/γ-CD giving rise to an enantioselective photoluminescence quenching due to the tendency of chiral enantiomers to form complexes with γ-CD in different molecular orientations as demonstrated by molecular docking studies. The approach, which is the first demonstration of applicability of molecular docking to show both enantioselective electrochemical and photoluminescence quenching capabilities of a graphene-related hybrid material, is truly new and may have broad interest in combination of experimental and computational methods for enantiosensing of chiral molecules. © 2016 Elsevier B.V.
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Graphene-encapsulated materials: Synthesis, applications and trends
Morales-Narváez E., Sgobbi L.F., Machado S.A.S., Merkoçi A. Progress in Materials Science; 86: 1 - 24. 2017. 10.1016/j.pmatsci.2017.01.001. IF: 31.140
Graphene-based materials (GBM) are an exceptional type of materials that offer unprecedented application capabilities to the scientific and technologic community. The encapsulation of different materials such as drugs, nanoparticles, polymers, oxides and cells by GBM is leading to outstanding hybrid materials with unprecedented behaviours promising a myriad of advantageous applications, including micro/nanomotors, biosensing platforms, bio/imaging agents, drug delivery systems, potential tumour treatment alternatives, environmental remediation platforms, advanced batteries and novel supercapacitors. We present an overview on graphene-encapsulated materials and their most important synthesis pathways. In addition, we explore the synergistic functionalities provided by these composites and highlight the state-of-the-art related to energy, environmental and bio-applications, among others. Finally, we discuss their challenges and future outlooks. © 2017 Elsevier Ltd
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Magnetic nanoparticle-molecular imprinted polymer: A new impedimetric sensor for tributyltin detection
Zamora-Gálvez A., Mayorga-Matinez C.C., Parolo C., Pons J., Merkoçi A. Electrochemistry Communications; 82: 6 - 11. 2017. 10.1016/j.elecom.2017.07.007. IF: 4.396
Recently, molecular imprinted polymers (MIPs) were extensively used for separation and identification of specific molecules, replacing expensive and unstable biological receptors. Nonetheless, their application in electrochemical sensors has not been sufficiently explored. Here we report the use of a MIP as a specific receptor in a new highly sensitive tributyltin (TBT) electrochemical sensor. The sensor combines the specificity, pre-concentration capability and robustness of molecular imprinted polymer attached onto magnetic nanoparticles with the quantitative outputs of impedimetric measurements. The proposed device detects TBT in a concentration range of 5 pM to 5 μM with a low limit of detection (5.37 pM), which is lower than the one recommended for TBT in sea water by the US Environmental Protection Agency (EPA). We believe that this new electrochemical sensor can play an important role in the monitoring of the quality of sea and fresh waters worldwide. © 2017 Elsevier B.V.
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Mobile phone-based biosensing: An emerging “diagnostic and communication” technology
Quesada-González D., Merkoçi A. Biosensors and Bioelectronics; 92: 549 - 562. 2017. 10.1016/j.bios.2016.10.062. IF: 7.780
In this review we discuss recent developments on the use of mobile phones and similar devices for biosensing applications in which diagnostics and communications are coupled. Owing to the capabilities of mobile phones (their cameras, connectivity, portability, etc.) and to advances in biosensing, the coupling of these two technologies is enabling portable and user-friendly analytical devices. Any user can now perform quick, robust and easy (bio)assays anywhere and at any time. Among the most widely reported of such devices are paper-based platforms. Herein we provide an overview of a broad range of biosensing possibilities, from optical to electrochemical measurements; explore the various reported designs for adapters; and consider future opportunities for this technology in fields such as health diagnostics, safety & security, and environment monitoring. © 2016 Elsevier B.V.
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Nanocellulose in Sensing and Biosensing
Golmohammadi H., Morales-Narváez E., Naghdi T., Merkoçi A. Chemistry of Materials; 29 (13): 5426 - 5446. 2017. 10.1021/acs.chemmater.7b01170. IF: 9.466
Because of its multifunctional character, nanocellulose (NC) is one of the most interesting nature-based nanomaterials and is attracting attention in a myriad of fields such as biomaterials, engineering, biomedicine, opto/electronic devices, nanocomposites, textiles, cosmetics and food products. Moreover, NC offers a plethora of outstanding properties, including inherent renewability, biodegradability, commercial availability, flexibility, printability, low density, high porosity, optical transparency as well as extraordinary mechanical, thermal and physicochemical properties. Consequently, NC holds unprecedented capabilities that are appealing to the scientific, technologic and industrial community. In this review, we highlight how NC is being tailored and applied in (bio)sensing technology, whose results aim at displaying analytical information related to various fields such as clinical/medical diagnostics, environmental monitoring, food safety, physical/mechanical sensing, labeling and bioimaging applications. In fact, NC-based platforms could be considered an emerging technology to fabricate efficient, simple, cost-effective and disposable optical/electrical analytical devices for several (bio)sensing applications including health care, diagnostics, environmental monitoring, food quality control, forensic analysis and physical sensing. We foresee that many of the (bio)sensors that are currently based on plastic, glass or conventional paper platforms will be soon transferred to NC and this generation of (bio)sensing platforms could revolutionize the conventional sensing technology. © 2017 American Chemical Society.
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Nanomaterials connected to antibodies and molecularly imprinted polymers as bio/receptors for bio/sensor applications
Zamora-Gálvez A., Morales-Narváez E., Mayorga-Martinez C.C., Merkoçi A. Applied Materials Today; 9: 387 - 401. 2017. 10.1016/j.apmt.2017.09.006. IF: 0.000
Nowadays, nanomaterials are considered a pivotal tool for different fields such as textiles, energy, environment, electronics, photonics, food, agriculture, biomedicine and health care. This is due to their advantageous properties coming from their high surface area, among other physicochemical properties, compared to their respective bulk forms. Nanomaterials, while used in (bio)detection systems, have shown to be extremely valuable to improve the analytical performance of conventional/laboratory methods and move forward biosensing technology. The usage of nanomaterials has been widely spread over the last few years mainly thanks to the great advantages that they offer in the development of conceptually new biosensors or improving the existing ones. This review focuses on how the usage of different nanomaterials have impacted biosensing research underscoring two different types of receptors, including biological receptors such as antibodies and non-biological receptors like molecularly imprinted polymers. The performance of relevant biosensing platforms including lateral flow devices as well as other optical and electrochemical approaches integrating nanomaterials and (bio) receptors are also discussed. © 2017 Elsevier Ltd
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Nanomaterials-based enzyme electrochemical biosensors operating through inhibition for biosensing applications
Kurbanoglu S., Ozkan S.A., Merkoçi A. Biosensors and Bioelectronics; 89: 886 - 898. 2017. 10.1016/j.bios.2016.09.102. IF: 7.780
In recent years great progress has been made in applying nanomaterials to design novel biosensors. Use of nanomaterials offers to biosensing platforms exceptional optical, electronic and magnetic properties. Nanomaterials can increase the surface of the transducing area of the sensors that in turn bring an increase in catalytic behaviors. They have large surface-to-volume ratio, controlled morphology and structure that also favor miniaturization, an interesting advantage when the sample volume is a critical issue. Biosensors have great potential for achieving detect-to-protect devices: devices that can be used in detections of pollutants and other treating compounds/analytes (drugs) protecting citizens' life. After a long term focused scientific and financial efforts/supports biosensors are expected now to fulfill their promise such as being able to perform sampling and analysis of complex samples with interest for clinical or environment fields. Among all types of biosensors, enzymatic biosensors, the most explored biosensing devices, have an interesting property, the inherent inhibition phenomena given the enzyme-substrate complex formation. The exploration of such phenomena is making remarkably important their application as research and applied tools in diagnostics. Different inhibition biosensor systems based on nanomaterials modification has been proposed and applied. The role of nanomaterials in inhibition-based biosensors for the analyses of different groups of drugs as well as contaminants such as pesticides, phenolic compounds and others, are discussed in this review. This deep analysis of inhibition-based biosensors that employ nanomaterials will serve researchers as a guideline for further improvements and approaching of these devices to real sample applications so as to reach society needs and such biosensor market demands. © 2016 Elsevier B.V.
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Paper strip-embedded graphene quantum dots: A screening device with a smartphone readout
Álvarez-DIduk R., Orozco J., Merkoçi A. Scientific Reports; 7 (1, 976) 2017. 10.1038/s41598-017-01134-3. IF: 4.259
Simple, inexpensive and rapid sensing systems are very demanded for a myriad of uses. Intrinsic properties of emerging paper-based analytical devices have demonstrated considerable potential to fulfill such demand. This work reports an easy-to-use, low cost, and disposable paper-based sensing device for rapid chemical screening with a smartphone readout. The device comprises luminescent graphene quantum dots (GQDs) sensing probes embedded into a nitrocellulose matrix where the resonance energy transfer phenomenon seems to be the sensing mechanism. The GQDs probes were synthesized from citric acid by a pyrolysis procedure, further physisorbed and confined into small wax-traced spots on the nitrocellulose substrate. The GQDs were excited by an UV LED, this, is powered by a smartphone used as both; energy source and imaging capture. The LED was contained within a 3D-printed dark chamber that isolates the paper platform from external light fluctuations leading to highly reproducible data. The cellulose-based device was proven as a promising screening tool for phenols and polyphenols in environmental and food samples, respectively. It opens up new opportunities for simple and fast screening of organic compounds and offers numerous possibilities for versatile applications. It can be especially useful in remote settings where sophisticated instrumentation is not always available. © 2017 The Author(s).
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Production of biofunctionalized MoS2 flakes with rationally modified lysozyme: A biocompatible 2D hybrid material
Siepi M., Morales-Narváez E., Domingo N., Monti D.M., Notomista E., Merkoçi A. 2D Materials; 4 (3, 035007) 2017. 10.1088/2053-1583/aa7966. IF: 6.937
Bioapplications of 2D materials embrace demanding features in terms of environmental impact, toxicity and biocompatibility. Here we report on the use of a rationally modified lysozyme to assist the exfoliation of Mos2 bulk crystals suspended in water through ultrasonic exfoliation. The design of the proposed lysozyme derivative provides this exfoliated 2D-materail with both, hydrophobic groups that interact with the surface of Mos2 and hydrophilic groups exposed to the aqueous medium, which hinders its re-Aggregation. This approach, clarified also by molecular docking studies, leads to a stable material (ζ-potential, 27 ?} 1 mV) with a yield of up to 430 μg ml-1. The bio-hybrid material was characterized in terms of number of layers and optical properties according to different slots separated by diverse centrifugal forces. Furthermore the obtained material was proved to be biocompatible using human normal keratinocytes and human cancer epithelial cells, whereas the method was demonstrated to be applicable to produce other 2D materials such as graphene. This approach is appealing for the advantageous production of high quality Mos2 flakes and their application in biomedicine and biosensing. Moreover, this method can be applied to different starting materials, making the denatured lysozyme a promising bio-Tool for surface functionalization of 2D materials. © 2017 IOP Publishing Ltd.
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Rapid on-chip apoptosis assay on human carcinoma cells based on annexin-V/quantum dot probes
Montón H., Medina-Sánchez M., Soler J.A., Chałupniak A., Nogués C., Merkoçi A. Biosensors and Bioelectronics; 94: 408 - 414. 2017. 10.1016/j.bios.2017.03.034. IF: 7.780
Despite all the efforts made over years to study the cancer expression and the metastasis event, there is not a clear understanding of its origins and effective treatment. Therefore, more specialized and rapid techniques are required for studying cell behaviour under different drug-based treatments. Here we present a quantum dot signalling-based cell assay carried out in a segmental microfluidic device that allows studying the effect of anti-cancer drugs in cultured cell lines by monitoring phosphatidylserine translocation that occurs in early apoptosis. The developed platform combines the automatic generation of a drug gradient concentration, allowing exposure of cancer cells to different doses, and the immunolabeling of the apoptotic cells using quantum dot reporters. Thereby a complete cell-based assay for efficient drug screening is performed showing a clear correlation between drug dose and amount of cells undergoing apoptosis. © 2017 Elsevier B.V.
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Straightforward Immunosensing Platform Based on Graphene Oxide-Decorated Nanopaper: A Highly Sensitive and Fast Biosensing Approach
Cheeveewattanagul N., Morales-Narváez E., Hassan A.-R.H.A., Bergua J.F., Surareungchai W., Somasundrum M., Merkoçi A. Advanced Functional Materials; 27 (38, 1702741) 2017. 10.1002/adfm.201702741. IF: 12.124
Immunoassays are nowadays a crucial tool for diagnostics and drug development. However, they often involve time-consuming procedures and need at least two antibodies in charge of the capture and detection processes, respectively. This study reports a nanocomposite based on graphene oxide-coated nanopaper (GONAP) facilitating an advantageous immunosensing platform using a single antibody and without the need for washing steps. The hydrophilic, porous, and photoluminescence-quenching character of GONAP allows for the adsorption and quenching of photoluminescent quantum dots nanocrystals complexed with antibodies (Ab-QDs), enabling a ready-to-use immunosensing platform. The photoluminescence is recovered upon immunocomplex (antibody-antigen) formation which embraces a series of interactions (hydrogen bonding, electrostatic, hydrophobic, and Van der Waals interactions) that trigger desorption of the antigen-Ab-QD complex from GONAP surface. However, the antigen is then attached onto the GONAP surface by electrostatic interactions leading to a spacer (greater than ≈20 nm) between Ab-QDs and GONAP and thus hindering nonradiative energy transfer. It is demonstrated that this simple—yet highly sensitive—platform represents a virtually universal immunosensing approach by using small-sized and big-sized targets as model analytes, those are, human-IgG protein and Escherichia coli bacteria. In addition, the assay is proved effective in real matrices analysis, including human serum, poultry meat, and river water. GONAP opens the way to conceptually new paper-based devices for immunosensing, which are amenable to point of care applications and automated diagnostics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Toward integrated detection and graphene-based removal of contaminants in a lab-on-a-chip platform
Chałupniak A., Merkoçi A. Nano Research; 10 (7): 2296 - 2310. 2017. 10.1007/s12274-016-1420-3. IF: 7.354
A novel, miniaturized microfluidic platform was developed for the simultaneous detection and removal of polybrominated diphenyl ethers (PBDEs). The platform consists of a polydimethylsiloxane (PDMS) microfluidic chip for an immunoreaction step, a PDMS chip with an integrated screen-printed electrode (SPCE) for detection, and a PDMS-reduced graphene oxide (rGO) chip for physical adsorption and subsequent removal of PBDE residues. The detection was based on competitive immunoassay-linked binding between PBDE and PBDE modified with horseradish peroxidase (HRP-PBDE) followed by the monitoring of enzymatic oxidation of o-aminophenol (o-AP) using square wave anodic stripping voltammetry (SW-ASV). PBDE was detected with good sensitivity and a limit of detection similar to that obtained with a commercial colorimetric test (0.018 ppb), but with the advantage of using lower reagent volumes and a reduced analysis time. The use of microfluidic chips also provides improved linearity and a better reproducibility in comparison to those obtained with batch-based measurements using screen-printed electrodes. In order to design a detection system suitable for toxic compounds such as PBDEs, a reduced graphene oxide–PDMS composite was developed and optimized to obtain increased adsorption (based on both the hydrophobicity and π–π stacking between rGO and PBDE molecules) compared to those of non-modified PDMS. To the best of our knowledge, this is the first demonstration of electrochemical detection of flame retardants and a novel application of the rGO-PDMS composite in a biosensing system. This system can be easily applied to detect any analyte using the appropriate immunoassay and it supports operation in complex matrices such as seawater. [Figure not available: see fulltext.]. © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
2016
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Bio(Sensing) devices based on ferrocene–functionalized graphene and carbon nanotubes
Rabti A., Raouafi N., Merkoçi A. Carbon; 108: 481 - 514. 2016. 10.1016/j.carbon.2016.07.043. IF: 6.198
Both carbon nanotubes (CNTs) and graphene are important pillars in the ongoing efforts to devise new applications in nanotechnology. One of their most promising applications is building devices such as sensors and biosensors, which is important step for the development of personalized medical healthcare devices. Mediators are usually used and sought to modify the physicochemical properties of these materials. In this review, we highlight the importance of the functionalization of CNT and graphene derivatives with redox molecules taking ferrocene derivatives as a model molecule. The employed techniques during (bio)sensing measurements using various functionalization strategies are also described. In addition, we discuss various aspects related to the applications of ferrocene–modified CNTs and graphene in electrochemical sensors and biosensors with a focus on the explanation of both CNTs/graphene and ferrocene contributions in the catalytic systems, which in turn enhance the analytical performance of the (bio)sensing devices. © 2016 Elsevier Ltd
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Control of Electron-transfer in Immunonanosensors by Using Polyclonal and Monoclonal Antibodies
Mars A., Parolo C., de la Escosura-Muñiz A., Raouafi N., Merkoçi A. Electroanalysis; 28 (8): 1795 - 1802. 2016. 10.1002/elan.201500646. IF: 2.471
The design and operation of biosensors is not trivial. For instance, variation in the output signal during monitoring of analytes can not usually be controlled. Hence, if such control were possible, and could be triggered on demand, it would greatly facilitate system design and operation. Herein, we report the design of two types of voltamperometric immunosensors, in which the magnitude of the current output signal (differential pulse voltammetry [DPV]) can be increased or decreased as needed. The designed systems use monoclonal and polyclonal anti-human IgG antibodies, conjugated to monopodal ferrocene-modified gold nanoparticles that are casted onto screen-printed carbon electrodes (Ab/mFcL/AuNPs/SPCEs). Upon addition of human IgG as antigen, the systems exhibit opposite responses according to the Ab: the current decreases when monoclonal Ab is used, whereas it increases when polyclonal Ab is used. We attributed the former response to inhibition of electron-transfer (due to the formation of a protein layer), and the latter response, to a global increase in electron transfer (induced by the aggregation of gold nanoparticles). These effects were confirmed by studying a custom-made lipoic acid-based bipodal ligand, which confirmed that the increase in current is effectively induced by the aggregation of the modified nanoparticles (pAb/mFcL/AuNPs). Both sensors have large dynamic ranges, although the pAb-based one was found to be 3.3-times more sensitive. Tests of selectivity and specificity for ovalbumin, α-lactalbumin and serum bovine albumin showed that the immunosensors are highly selective and specific, even in the presence of up to 1000-fold levels of potentially competitive proteins. The limit of detection for human IgG using the pAb/mFcL/AuNP bioconjugate was estimated to be 0.85 ng/mL. The pAb/mFcL/AuNPs-based biosensor has used to determine amounts of human IgG in real sample. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Detection of parathyroid hormone-like hormone in cancer cell cultures by gold nanoparticle-based lateral flow immunoassays
Chamorro-Garcia A., de la Escosura-Muñiz A., Espinoza-Castañeda M., Rodriguez-Hernandez C.J., de Torres C., Merkoçi A. Nanomedicine: Nanotechnology, Biology, and Medicine; 12 (1): 53 - 61. 2016. 10.1016/j.nano.2015.09.012. IF: 5.671
Parathyroid hormone-like hormone (PTHLH) exerts relevant roles in progression and dissemination of several tumors. However, factors influencing its production and secretion have not been fully characterized. The main limitation is the lack of specific, sensitive and widely available techniques to detect and quantify PTHLH. We have developed a lateral flow immunoassay using gold nanoparticles label for the fast and easy detection of PTHLH in lysates and culture media of three human cell lines (HaCaT, LA-N-1, SK-N-AS). Levels in culture media and lysates ranged from 11 to 20 ng/mL and 0.66 to 0.87 μg/mL respectively. Results for HaCaT are in agreement to the previously reported, whereas LA-N-1 and SK-N-AS have been evaluated for the first time. The system also exhibits good performance in human serum samples. This methodology represents a helpful tool for future in vitro and in vivo studies of mechanisms involved in PTHLH production as well as for diagnostics. From the Clinical Editor: Parathyroid Hormone-like Hormone (PTHLH) is known to be secreted by some tumors. However, the detection of this peptide remains difficult. The authors here described their technique of using gold nanoparticles as label for the detection of PTHLH by Lateral-flow immunoassays (LFIAs). The positive results may also point a way to using the same technique for the rapid determination of other relevant cancer proteins. © 2015 Elsevier Inc.
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Emerging Nanomaterials for Analytical Detection
Alarcon-Angeles G., Álvarez-Romero G.A., Merkoçi A. Comprehensive Analytical Chemistry; 74: 195 - 246. 2016. 10.1016/bs.coac.2016.03.022. IF: 0.000
This chapter revises the recent trends in the use and applications of nanomaterials (NMs) in analytical detections with special interest in food quality control. The most important NMs such as gold nanoparticles, quantum dots, carbon-related nanomaterials and their properties are introduced. We show how analytical science is taking advantage of such materials to either develop new analytical methods or improve the existing technologies. Biosensing, in both batch and lab-on-a-chip formats, is one of the most important analytical technologies that is in the forefront of such interesting applications. The use of these materials in some conventional analytical techniques such as chromatography between others also is discussed. Examples related to such NMs application in real food samples with interest for quality control as well as detection of various interesting compounds such as glucose, amino acids, DNA (normally present in food) or other species that are usually of interest to be detected for safety reasons (bacteria, toxins) are discussed. Aspects related to the improvements of analytical performance in terms of detection limits, stability, selectivity, etc. using various NMs and detection technologies also are discussed. © 2016 Elsevier B.V.
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Enhanced detection of quantum dots labeled protein by simultaneous bismuth electrodeposition into microfluidic channel
Medina-Sánchez M., Miserere S., Cadevall M., Merkoçi A. Electrophoresis; 37 (3): 432 - 437. 2016. 10.1002/elps.201500288. IF: 2.482
In this study, we propose an electrochemical immunoassay into a disposable microfluidic platform, using quantum dots (QDs) as labels and their enhanced detection using bismuth as an alternative to mercury electrodes. CdSe@ZnS QDs were used to tag human IgG as a model protein and detected through highly sensitive stripping voltammetry of the dissolved metallic component (cadmium in our case). The modification of the screen printed carbon electrodes (SPCEs) was done by a simple electrodeposition of bismuth that was previously mixed with the sample containing QDs. A magneto-immunosandwich assay was performed using a micromixer. A magnet placed at its outlet in order to capture the magnetic beads used as solid support for the immunoassay. SPCEs were integrated at the end of the channel as detector. Different parameters such as bismuth concentration, flow rate, and incubation times, were optimized. The LOD for HIgG in presence of bismuth was 3.5 ng/mL with a RSD of 13.2%. This LOD was about 3.3-fold lower than the one obtained without bismuth. Furthermore, the sensitivity of the system was increased 100-fold respect to experiments carried out with classical screen-printed electrodes, both in presence of bismuth. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Ferrocene-functionalized graphene electrode for biosensing applications
Rabti A., Mayorga-Martinez C.C., Baptista-Pires L., Raouafi N., Merkoçi A. Analytica Chimica Acta; 926: 28 - 35. 2016. 10.1016/j.aca.2016.04.010. IF: 4.712
A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of H2O2 and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications. © 2016 Elsevier B.V.
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Graphene-based Janus micromotors for the dynamic removal of pollutants
Orozco J., Mercante L.A., Pol R., Merkoçi A. Journal of Materials Chemistry A; 4 (9): 3371 - 3378. 2016. 10.1039/c5ta09850e. IF: 8.262
Persistent organic pollutants (POPs) are ubiquitous in the environment as a result of modern industrial processes. We present an effective POPs decontamination strategy based on their dynamic adsorption at the surface of reduced graphene oxide (rGO)-coated silica (SiO2)-Pt Janus magnetic micromotors for their appropriate final disposition. While the motors rapidly move in a contaminated solution, the adsorption of POPs efficiently takes place in a very short time. Characterization of the micromotors both from the materials and from the motion point of view was performed. Polybrominated diphenyl ethers (PBDEs) and 5-chloro-2-(2,4-dichlorophenoxy) phenol (triclosan) were chosen as model POPs and the removal of the contaminants was efficiently achieved. The rGO-coated micromotors demonstrated superior adsorbent properties with respect to their concomitant GO-coated micromotors, static rGO-coated particles and dynamic silica micromotors counterparts. The extent of decontamination was studied over the number of micromotors, whose magnetic properties were used for their collection from environmental samples. The adsorption properties were maintained for 4 cycles of micromotors reuse. The new rGO-coated SiO2 functional material-based micromotors showed outstanding capabilities towards the removal of POPs and their further disposition, opening up new possibilities for efficient environmental remediation of these hazardous compounds. © 2016 The Royal Society of Chemistry.
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High-performance sensor based on copper oxide nanoparticles for dual detection of phenolic compounds and a pesticide
Pino F., Mayorga-Martinez C.C., Merkoçi A. Electrochemistry Communications; 71: 33 - 37. 2016. 10.1016/j.elecom.2016.08.001. IF: 4.569
The development of nanomaterials for use as bio-recognition elements is important in the evolution of biosensing systems. In the present article we present a sensing system based on copper oxide nanoparticles (CuO NPs) for the detection of phenolic compounds and pesticides. This sensor takes advantage of the interactions of CuO NPs with toxic compounds that in turn generate an electrochemical signal related to the concentration of the pollutants. © 2016
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Hybrid self-assembled materials constituted by ferromagnetic nanoparticles and tannic acid: A theoretical and experimental investigation
Santos A.F.M., Macedo L.J.A., Chaves M.H., Espinoza-Castañeda M., Merkoçi A., Limac F.D.C.A., Cantanhêde W. Journal of the Brazilian Chemical Society; 27 (4): 727 - 734. 2016. 10.5935/0103-5053.20150322. IF: 1.096
Hybrid magnetite materials are interesting for both biomedical and catalytic applications due to their well-known biocompatibility, as well as their magnetic and electric properties. In this work we prepared Fe3 O4 nanoparticles (NPs) coated with tannic acid (TA), a natural polyphenol, through two different synthetic routes, aiming to understand the influence of TA in the synthesis step and contribute to the development of water-dispersible magnetic materials. The coating process was verified by information obtained from transmission electron microscopy (TEM), zeta-potential and Fourier transform infrared (FTIR) spectroscopy. The incorporation of TA after Fe3 O4 NPs production generated spherical NPs smaller than 10 nm, suggesting that TA plays a fundamental role in the nucleation and organization of Fe3 O4 NPs. Data from both density functional theory (DFT) and FTIR allowed us to infer that Fe3 O4 interacts mainly with the carbonyl groups of TA. Hybrid materials having improved water-dispersibility are very attractive for biomedical applications. ©2016 Sociedade Brasileira de Química.
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Magnetic Bead/Gold Nanoparticle Double-Labeled Primers for Electrochemical Detection of Isothermal Amplified Leishmania DNA
De La Escosura-Muñiz A., Baptista-Pires L., Serrano L., Altet L., Francino O., Sánchez A., Merkoçi A. Small; 12 (2): 205 - 213. 2016. 10.1002/smll.201502350. IF: 8.315
A novel methodology for the isothermal amplification of Leishmania DNA using labeled primers combined with the advantages of magnetic purification/preconcentration and the use of gold nanoparticle (AuNP) tags for the sensitive electrochemical detection of such amplified DNA is developed. Primers labeled with AuNPs and magnetic beads (MBs) are used for the first time for the isothermal amplification reaction, being the amplified product ready for the electrochemical detection. The electrocatalytic activity of the AuNP tags toward the hydrogen evolution reaction allows the rapid quantification of the DNA on screen-printed carbon electrodes. Amplified products from the blood of dogs with Leishmania (positive samples) are discriminated from those of healthy dogs (blank samples). Quantitative studies demonstrate that the optimized method allows us to detect less than one parasite per microliter of blood (8 × 10-3 parasites in the isothermal amplification reaction). This pioneering approach is much more sensitive than traditional methods based on real-time polymerase chain reaction (PCR), and is also more rapid, cheap, and user-friendly. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Microfluidic platform for environmental contaminants sensing and degradation based on boron-doped diamond electrodes
Medina-Sánchez M., Mayorga-Martinez C.C., Watanabe T., Ivandini T.A., Honda Y., Pino F., Nakata A., Fujishima A., Einaga Y., Merkoçi A. Biosensors and Bioelectronics; 75: 365 - 374. 2016. 10.1016/j.bios.2015.08.058. IF: 7.476
We have developed a lab-on-a-chip (LOC) platform for electrochemical detection and degradation of the pesticide atrazine (Atz). It is based on boron-doped diamond (BDD) electrodes and a competitive magneto-enzyme immunoassay (EIA) that enables high sensitivity. To detect the enzymatic reaction, we employed a BDD electrode modified with platinum nanoparticles (PtNPs), as a highly conductive catalytic transducer. Chronoamperometry revealed a limit of detection (LOD) of 3.5pM for atrazine, which, to the best of our knowledge, is one of the lowest value published to date. Finally, we degraded Atz in the same platform, using a bare BDD electrode that features remarkable corrosion stability, a wide potential window, and much higher O2 overvoltage as compared to conventional electrodes. These characteristics enable the electrode to produce a greater amount of HO• on the anode surface than do conventional electrodes and consequently, to destroy the pollutant more rapidly. Our new LOC platform might prove interesting as a smart system for detection and remediation of diverse pesticides and other contaminants. © 2015 Elsevier B.V.
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Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose: Via ammonia exposure: Visual detection of volatile compounds in a piece of plasmonic nanopaper
Heli B., Morales-Narváez E., Golmohammadi H., Ajji A., Merkoçi A. Nanoscale; 8 (15): 7984 - 7991. 2016. 10.1039/c6nr00537c. IF: 7.760
The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging. © 2016 The Royal Society of Chemistry.
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Molecularly Imprinted Polymer-Decorated Magnetite Nanoparticles for Selective Sulfonamide Detection
Zamora-Gálvez A., Ait-Lahcen A., Mercante L.A., Morales-Narváez E., Amine A., Merkoçi A. Analytical Chemistry; 88 (7): 3578 - 3584. 2016. 10.1021/acs.analchem.5b04092. IF: 5.886
Sulfonamides are known not only to be antimicrobial drugs that lead to antimicrobial resistance but also to be chemotherapeutic agents that may be allergenic and potentially carcinogenic, which represents a potentially hazardous compound once present in soil or water. Herein, a hybrid material based on molecularly imprinted polymer (MIP)-decorated magnetite nanoparticles for specific and label-free sulfonamide detection is reported. The composite has been characterized using different spectroscopic and imaging techniques. The magnetic properties of the composite are used to separate, preconcentrate, and manipulate the analyte which is selectively captured by the MIP onto the surface of the composite. Screen printed electrodes have been employed to monitor the impedance levels of the whole material, which is related to the amount of the captured analyte, via electrochemical impedance spectroscopy. This composite-based sensing system exhibits an extraordinary limit of detection of 1 × 10-12 mol L-1 (2.8 × 10-4 ppb) (S/N = 3), which is close to those obtained with liquid chromatography and mass spectrometry, and it was demonstrated to screen sulfamethoxazole in a complex matrix such as seawater, where according to the literature sulfonamides content is minimum compared with other environmental samples. © 2016 American Chemical Society.
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Nanobiosensors in diagnostics
Chamorro-Garcia A., Merkoçi A. Nanobiomedicine; 3 2016. 10.1177/1849543516663574.
Medical diagnosis has been greatly improved thanks to the development of new techniques capable of performing very sensitive detection and quantifying certain parameters. These parameters can be correlated with the presence of specific molecules and their quantity. Unfortunately, these techniques are demanding, expensive, and often complicated. On the other side, progress in other fields of science and technology has contributed to the rapid growth of nanotechnology. Although being an emerging discipline, nanotechnology has raised huge interest and expectations. Most of the enthusiasm comes from new possibilities and properties of nanomaterials. Biosensors (simple, robust, sensitive, cost-effective) combined with nanomaterials, also called nanobiosensors, are serving as bridge between advanced detection/diagnostics and daily/routine tests. Here we review some of the latest applications of nanobiosensors in diagnostics field. © 2016, ©The Author(s) 2016.
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Nanochannels for electrical biosensing
de la Escosura-Muñiz A., Merkoçi A. TrAC - Trends in Analytical Chemistry; 79: 134 - 150. 2016. 10.1016/j.trac.2015.12.003. IF: 7.487
This review shows the recent trends on the use of both single and array nanochannels for electrical biosensing applications. Some general considerations on the principles of the stochastic sensing, together with an overview about the common routes for nanochannels preparation before focusing on the applications for DNA, protein, virus, toxin and other analytes detection are given. Emerging materials used to obtain nanochannels, such as graphene and its analogues as well as novel systems based on the use of nanoparticles in combination with nanochannels are discussed. Aspects related to the analytical performance of the developed devices are also discussed. Finally prospects for future improvements and applications of this technology are included. © 2015 Elsevier B.V.
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Paper-based sensors and assays: A success of the engineering design and the convergence of knowledge areas
López-Marzo A.M., Merkoçi A. Lab on a Chip - Miniaturisation for Chemistry and Biology; 16 (17): 3150 - 3176. 2016. 10.1039/c6lc00737f. IF: 5.586
This review shows the recent advances and state of the art in paper-based analytical devices (PADs) through the analysis of their integration with microfluidics and LOC micro- and nanotechnologies, electrochemical/optical detection and electronic devices as the convergence of various knowledge areas. The important role of the paper design/architecture in the improvement of the performance of sensor devices is discussed. The discussion is fundamentally based on μPADs as the new generation of paper-based (bio)sensors. Data about the scientific publication ranking of PADs, illustrating their increase as an experimental research topic in the past years, are supplied. In addition, an analysis of the simultaneous evolution of PADs in academic lab research and industrial commercialization highlighting the parallelism of the technological transfer from academia to industry is displayed. A general overview of the market behaviour, the leading industries in the sector and their commercialized devices is given. Finally, personal opinions of the authors about future perspectives and tendencies in the design and fabrication technology of PADs are disclosed. © 2016 The Royal Society of Chemistry.
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Water activated graphene oxide transfer using wax printed membranes for fast patterning of a touch sensitive device
Baptista-Pires L., Mayorga-Martínez C.C., Medina-Sánchez M., Montón H., Merkoçi A. ACS Nano; 10 (1): 853 - 860. 2016. 10.1021/acsnano.5b05963. IF: 13.334
We demonstrate a graphene oxide printing technology using wax printed membranes for the fast patterning and water activation transfer using pressure based mechanisms. The wax printed membranes have 50 μm resolution, longtime stability and infinite shaping capability. The use of these membranes complemented with the vacuum filtration of graphene oxide provides the control over the thickness. Our demonstration provides a solvent free methodology for printing graphene oxide devices in all shapes and all substrates using the roll-toroll automatized mechanism present in the wax printing machine. Graphene oxide was transferred over a wide variety of substrates as textile or PET in between others. Finally, we developed a touch switch sensing device integrated in a LED electronic circuit. © 2015 American Chemical Society.
2015
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Alzheimer's disease biomarkers detection in human samples by efficient capturing through porous magnetic microspheres and labelling with electrocatalytic gold nanoparticles
de la Escosura-Muñiz A., Plichta Z., Horák D., Merkoçi A. Biosensors and Bioelectronics; 67: 162 - 169. 2015. 10.1016/j.bios.2014.07.086. IF: 6.409
A nanobiosensor based on the use of porous magnetic microspheres (PMM) as efficient capturing/pre-concentrating platform is presented for detection of Alzheimer's disease (AD) biomarkers. These PMMs prepared by a multistep swelling polymerization combined with iron oxide precipitation afford carboxyl functional groups suitable for immobilization of antibodies on the particle surface allowing an enhanced efficiency in the capturing of AD biomarkers from human serum samples. The AD biomarkers signaling is produced by gold nanoparticle (AuNP) tags monitored through their electrocatalytic effect towards hydrogen evolution reaction (HER). Novel properties of PMMs in terms of high functionality and high active area available for enhanced catalytic activity of the captured AuNPs electrocatalytic tags are exploited for the first time. A thorough characterization by scanning transmission electron microscope in high angle annular dark field mode (STEM-HAADF) demonstrates the enhanced ability of PMMs to capture a higher quantity of analyte and consequently of electrocatalytic label, when compared with commercially available microspheres. The optimized and characterized PMMs are also applied for the first time for the detection of beta amyloid and ApoE at clinical relevant levels in cerebrospinal fluid (CSF), serum and plasma samples of patients suffering from AD. © 2014 Elsevier B.V.
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An iridium oxide nanoparticle and polythionine thin film based platform for sensitive Leishmania DNA detection
Mayorga-Martinez C.C., Chamorro-García A., Serrano L., Rivas L., Quesada-Gonzalez D., Altet L., Francino O., Sánchez A., Merkoçi A. Journal of Materials Chemistry B; 3 (26): 5166 - 5171. 2015. 10.1039/c5tb00545k. IF: 4.726
An impedimetric label-free genosensor for high sensitive DNA detection is developed. This system is based on a screen-printed carbon electrode modified with the thionine layer and iridium oxide nanoparticles (IrO
2 NP). An aminated oligonucleotide probe is immobilized on the IrO2 NP/polythionine modified electrode and ethanolamine was used as a blocking agent. Different diluted PCR amplified DNA samples have been detected. The selectivity and reproducibility of this system are studied and the system was highly reproducible with RSD ≈ 15% and sensitive enough while using 2% of ethanolamine during the blocking step employed for genosensor preparation. © The Royal Society of Chemistry.
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Annexin-V/quantum dot probes for multimodal apoptosis monitoring in living cells: Improving bioanalysis using electrochemistry
Montón H., Parolo C., Aranda-Ramos A., Merkoçi A., Nogués C. Nanoscale; 7 (9): 4097 - 4104. 2015. 10.1039/c4nr07191c. IF: 7.394
There is a great demand to develop novel techniques that allow useful and complete monitoring of apoptosis, which is a key factor of several diseases and a target for drug development. Here, we present the use of a novel dual electrochemical/optical label for the detection and study of apoptosis. We combined the specificity of Annexin-V for phosphatidylserine, a phospholipid expressed in the outer membrane of apoptotic cells, with the optical and electrochemical properties of quantum dots to create a more efficient label. Using this conjugate we addressed three important issues: (i) we made the labeling of apoptotic cells faster (30 min) and easier; (ii) we fully characterized the samples by common cell biological techniques (confocal laser scanning microscopy, scanning electron microscopy and flow cytometry); and (III) we developed a fast, cheap and quantitative electrochemical detection method for apoptotic cells with results in full agreement with those obtained by flow cytometry. This journal is © The Royal Society of Chemistry.
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Antithyroid drug detection using an enzyme cascade blocking in a nanoparticle-based lab-on-a-chip system
Kurbanoglu S., Mayorga-Martinez C.C., Medina-Sánchez M., Rivas L., Ozkan S.A., Merkoçi A. Biosensors and Bioelectronics; 67: 670 - 676. 2015. 10.1016/j.bios.2014.10.014. IF: 6.409
A methimazole (MT) biosensor based on a nanocomposite of magnetic nanoparticles (MNPs) functionalized with iridium oxide nanoparticles (IrOx NPs) and tyrosinase (Tyr) immobilized onto screen printed electrode (SPE) by using a permanent magnet is presented. This system is evaluated in batch mode via chelating copper at the active site of tyrosinase and in flow mode by thioquinone formation. The MT detection in flow mode is achieved using a hybrid polydimethylsiloxane/polyester amperometric lab-on-a-chip (LOC) microsystem with an integrated SPE. Both systems are very sensitive with low limit of detection (LOD): 0.006. μM and 0.004. μM for batch and flow modes, respectively. Nevertheless, the flow mode has advantages such as its reusability, automation, low sample volume (6. μL), and fast response (20. s). Optimization and validation parameters such as enzyme-substrate amount, flow rate, inhibition conditions, repeatability and reproducibility of the biosensor have been performed. The proposed methods have been applied in MT detection in spiked human serum and pharmaceutical dosage forms. © 2014 Elsevier B.V.
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Bismuth nanoparticles integration into heavy metal electrochemical stripping sensor
Cadevall M., Ros J., Merkoçi A. Electrophoresis; 36 (16): 1872 - 1879. 2015. 10.1002/elps.201400609. IF: 3.028
Between their many applications bismuth nanoparticles (BiNPs) are showing interest as pre-concentrators in heavy metals detection while being applied as working electrode modifiers used in electrochemical stripping analysis. From the different reported methods to synthesize BiNPs we are focused on the typical polyol method, largely used in these types of metallic and semi-metallic nanoparticles. This study presents the strategy for an easy control of the shape and size of BiNPs including nanocubes, nanosferes and triangular nanostructures. To improve the BiNP size and shape, different reducing agents (ethylene glycol or sodium hypophosphite) and stabilizers (polyvinyl pyrrolidone, PVP, in different amounts) have been studied. The efficiency of BiNPs for heavy metals analysis in terms of detection sensitivity while being used as modifiers of screen-printed carbon electrodes including the applicability of the developed device in real sea water samples is shown. A parallel study between the obtained nanoparticles and their performance in heavy metal sensing has been described in this communication. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Eco-friendly electrochemical lab-on-paper for heavy metal detection
Medina-Sánchez M., Cadevall M., Ros J., Merkoçi A. Analytical and Bioanalytical Chemistry; 2015. 10.1007/s00216-015-9022-6. IF: 3.436
A disposable electrochemical lateral flow paper-based sensing device for heavy metal detection is proposed. The quantification of lead and cadmium in aqueous samples is demonstrated in a range from 10 to 100 ppb with a limit of detection of 7 and 11 ppb respectively. Moreover, the platform itself, which is made of paper, served as a sample pretreatment material due to its filtering properties. Real samples, especially in which the matrix is usually turbid and would in principle need a previous filtration, are successfully analyzed. This lab-on-paper device is simple, low cost, easy to fabricate, and portable, being a promising tool for new point-of-care applications in environmental monitoring, public health, and food safety. © 2015 Springer-Verlag Berlin Heidelberg
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Electrochemical Impedance Spectroscopy (bio)sensing through hydrogen evolution reaction induced by gold nanoparticles
Mayorga-Martinez C.C., Chamorro-Garcia A., Merkoçi A. Biosensors and Bioelectronics; 67: 53 - 58. 2015. 10.1016/j.bios.2014.05.066. IF: 6.409
A new gold nanoparticle (AuNP) based detection strategy using Electrochemical Impedance Spectroscopy (EIS) through hydrogen evolution reaction (HER) is proposed. This EIS-HER method is used as an alternative to the conventional EIS based on [Fe(CN)6]3-/4- or [Ru(NH3)6]3+/2+ indicators. The proposed method is based on the HER induced by AuNPs. EIS measurements for different amounts of AuNP are registered and the charge transfer resistance (Rct) was found to correlate and be useful for their quantification. Moreover the effect of AuNP size on electrical properties of AuNPs for HER using this sensitive technique has been investigated. Different EIS-HER signals generated in the presence of AuNPs of different sizes (2, 5, 10, 15, 20, and 50nm) are observed, being the corresponding phenomena extendible to other nanoparticles and related catalytic reactions. This EIS-HER sensing technology is applied to a magneto-immunosandwich assay for the detection of a model protein (IgG) achieving improvements of the analytical performance in terms of a wide linear range (2-500ngmL-1) with a good limit of detection (LOD) of 0.31ngmL-1 and high sensitivity. Moreover, with this methodology a reduction of one order of magnitude in the LOD for IgG detection, compared with a chroamperometric technique normally used was achieved. © 2014 Elsevier B.V.
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Graphene quantum dots-based photoluminescent sensor: A multifunctional composite for pesticide detection
Zor E., Morales-Narváez E., Zamora-Gálvez A., Bingol H., Ersoz M., Merkoçi A. ACS Applied Materials and Interfaces; 7 (36): 20272 - 20279. 2015. 10.1021/acsami.5b05838. IF: 6.723
Due to their size and difficulty to obtain, cost/effective biological or synthetic receptors (e.g., antibodies or aptamers, respectively), organic toxic compounds (e.g., less than 1 kDa) are generally challenging to detect using simple platforms such as biosensors. This study reports on the synthesis and characterization of a novel multifunctional composite material, magnetic silica beads/graphene quantum dots/molecularly imprinted polypyrrole (mSGP). mSGP is engineered to specifically and effectively capture and signal small molecules due to the synergy among chemical, magnetic, and optical properties combined with molecular imprinting of tributyltin (291 Da), a hazardous compound, selected as a model analyte. Magnetic and selective properties of the mSGP composite can be exploited to capture and preconcentrate the analyte onto its surface, and its photoluminescent graphene quantum dots, which are quenched upon analyte recognition, are used to interrogate the presence of the contaminant. This multifunctional material enables a rapid, simple and sensitive platform for small molecule detection, even in complex mediums such as seawater, without any sample treatment. © 2015 American Chemical Society.
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Highly sensitive and rapid determination of Escherichia coli O157: H7 in minced beef and water using electrocatalytic gold nanoparticle tags
Hassan A.R.H.A.A., de la Escosura-Muñiz A., Merkoçi A. Biosensors and Bioelectronics; 67: 511 - 515. 2015. 10.1016/j.bios.2014.09.019. IF: 6.409
A simple, highly sensitive and specific immunosensing assay for rapid detection and quantification of Escherichia coli O157:H7 in meat and water samples based on the electrocatalytic properties of gold nanoparticles (AuNPs) towards hydrogen evolution reaction and superparamagnetic microbeads (MBs) as pre-concentration/purification platforms without the need of broth enrichment is developed for the first time. Minced beef and water samples inoculated with different concentrations of E. coli O157:H7 have been tested using anti-E. coli O157-magnetic beads conjugate (MBs-pECAb) as a capture platform and sandwiching afterwards with AuNPs modified with secondary antibodies (AuNPs-sECAb) and detected using chronoamperometric measurement with screen-printed carbon electrodes (SPCEs). Detection limits (LOD) of 148, 457 and 309CFU/mL were obtained in buffer solution, minced beef and tap water samples respectively, with a broad detection range of 102-105CFU/mL in all cases. Recoveries percentages after spiking of 5 different samples of both minced beef and tap water with 103 and 104CFU/mL were 94.7 and 90.4 (in beef) and 91.3 and 94.8% (in water), respectively. Specificity, reproducibility and comparison with a commercial lateral flow kit in terms of LOD and detection range were also studied showing clear advantages of the electrochemical method performance. The successful application of this AuNPs based technology in minced beef and tap water indicates the possibility of its using in various food items and other water resources. © 2014 Elsevier B.V.
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In situ production of biofunctionalized few-layer defect-free microsheets of graphene
Gravagnuolo A.M., Morales-Narváez E., Longobardi S., Da Silva E.T., Giardina P., Merkoçi A. Advanced Functional Materials; 25 (18): 2771 - 2779. 2015. 10.1002/adfm.201500016. IF: 11.805
Biological interfacing of graphene has become crucial to improve its biocompatibility, dispersability, and selectivity. However, biofunctionalization of graphene without yielding defects in its sp2-carbon lattice is a major challenge. Here, a process is set out for biofunctionalized defect-free graphene synthesis through the liquid phase ultrasonic exfoliation of raw graphitic material assisted by the self-assembling fungal hydrophobin Vmh2. This protein (extracted from the edible fungus Pleurotus ostreatus) is endowed with peculiar physicochemical properties, exceptional stability, and versatility. The unique properties of Vmh2 and, above all, its superior hydrophobicity, and stability allow to obtain a highly concentrated (≈440-510 μg mL-1) and stable exfoliated material (ζ-potential, +40/+70 mV). In addition controlled centrifugation enables the selection of biofunctionalized few-layer defect-free micrographene flakes, as assessed by Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and electrophoretic mobility. This biofunctionalized product represents a high value added material for the emerging applications of graphene in the biotechnological field such as sensing, nanomedicine, and bioelectronics technologies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Lab-in-a-syringe using gold nanoparticles for rapid immunosensing of protein biomarkers
Nunes Pauli G.E., De La Escosura-Muñiz A., Parolo C., Helmuth Bechtold I., Merkoçi A. Lab on a Chip; 15 (2): 399 - 405. 2015. 10.1039/c4lc01123f.
We have developed a paper and gold nanoparticle (AuNP)-based lab-in-a-syringe (LIS) for immunosensing of biomarkers. This simple diagnostic device features simultaneous sampling and vertical-flow operation, which means that unlike typical immunosensors, it does not suffer from any delay between sampling and detection. It can handle large-volume, low-concentration samples for analysis in diverse applications (e.g. biomedical, environmental, food, etc.). Furthermore, its operating range for sample concentration can be tuned by simply changing the volume of the syringed sample, which enables on-demand limits of detection (LOD). The LIS contains two nitrocellulose pads: the conjugate pad (which captures the analyte) and the detection pad (which signals the presence of the captured analyte) both embedded into reusable plastic cartridges. We demonstrated its efficiency in detecting human IgG (HIgG) (LOD: 1.0 ng mL-1) and prostate-specific antigen (PSA) (spiked urine samples; LOD: 1.9 ng mL-1). In the field, the LIS can be used for complete on-site analysis or to obtain partially analyzed samples (AuNPs with captured analyte) for subsequent detailed testing in specialized laboratories. This journal is © The Royal Society of Chemistry 2015.
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Label-free impedimetric aptasensor for ochratoxin-A detection using iridium oxide nanoparticles
Rivas L., Mayorga-Martinez C.C., Quesada-González D., Zamora-Gálvez A., De La Escosura-Muñiz A., Merkoçi A. Analytical Chemistry; 87 (10): 5167 - 5172. 2015. 10.1021/acs.analchem.5b00890. IF: 5.636
In this article, a novel aptasensor for ochratoxin A (OTA) detection based on a screen-printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles (IrO
2 NPs) is presented. The electrotransducer surface is modified with an electropolymerized film of PTH followed by the assembly of IrO2 NPs on which the aminated aptamer selective to OTA is exchanged with the citrate ions surrounding IrO2 NPs via electrostatic interactions with the same surface. Electrochemical impedance spectroscopy (EIS) in the presence of the [Fe(CN)6 ]-3/-4 redox probe is employed to characterize each step in the aptasensor assay and also for label-free detection of OTA in a range between 0.01 and 100 nM, obtaining one of the lowest limits of detection reported so far for label-free impedimetric detection of OTA (14 pM; 5.65 ng/kg). The reported system also exhibits a high reproducibility, a good performance with a white wine sample, and an excellent specificity against another toxin present in such sample. © 2015 American Chemical Society.
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Micro and nanomotors in diagnostics
Chałupniak A., Morales-Narváez E., Merkoçi A. Advanced Drug Delivery Reviews; 95: 104 - 116. 2015. 10.1016/j.addr.2015.09.004. IF: 15.038
Synthetic micro/nanomotors are tiny devices than can be self-propelled or externally powered in the liquid phase by different types of energy source including but not limited to: catalytic, magnetic or acoustic. Showing a myriad of mechanical movements, building block materials, sizes, shapes and propulsion mechanisms micro/nanomotors are amenable to diagnostics and therapeutics. Herein we describe the most relevant micro/nanomotors, their fabrication pathways, propulsion strategies as well as in vivo and in vitro applications related with oligonucleotides, proteins, cells and tissues. We also discuss the main challenges in these applications such as the influence of complex media and toxicity issues as well as future perspectives. © 2015 Elsevier B.V.
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Nanochannel array device operating through Prussian blue nanoparticles for sensitive label-free immunodetection of a cancer biomarker
Espinoza-Castañeda M., Escosura-Muñiz A.D.L., Chamorro A., Torres C.D., Merkoçi A. Biosensors and Bioelectronics; 67: 107 - 114. 2015. 10.1016/j.bios.2014.07.039. IF: 6.409
A novel nanochannel array (NC) device that operates through Prussian blue nanoparticles (PBNPs) as redox indicator for sensitive label free immunodetection of a cancer biomarker is presented. Stable and narrow-sized (around 4nm) PBNPs, protected by polyvinylpyrrolidone, exhibited a well-defined and reproducible redox behavior and were successfully applied for the voltammetric evaluation of the nanochannels (20nm pore sized) blockage due to the immunocomplex formation. The bigger size of the PBNPs compared with ionic indicators such as the [Fe(CN)6]4-/3- system leads to an increase in the steric effects hindering their diffusion toward the signaling electrode which in turn is transduced to an improvement of the detection limit from 200μgmL-1 to 34pg human IgGmL-1. This novel and effective PBNPs-NC technology for the detection of small proteins captured inside the nanochannels is successfully applied for the quantification of a cancer biomarker (parathyroid hormone-related protein, PTHrP) in a real clinical scenario such as cell culture medium. The achieved label-free detection of PTHrP at levels of 50ngmL-1 is with great interest to study relevant functions that this protein exerts in normal tissues and cancer. © 2014 Elsevier B.V.
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Nanopaper as an Optical Sensing Platform
Morales-Narváez E., Golmohammadi H., Naghdi T., Yousefi H., Kostiv U., Horák D., Pourreza N., Merkoçi A. ACS Nano; 9 (7): 7296 - 7305. 2015. 10.1021/acsnano.5b03097. IF: 12.881
Bacterial cellulose nanopaper (BC) is a multifunctional material known for numerous desirable properties: sustainability, biocompatibility, biodegradability, optical transparency, thermal properties, flexibility, high mechanical strength, hydrophilicity, high porosity, broad chemical-modification capabilities and high surface area. Herein, we report various nanopaper-based optical sensing platforms and describe how they can be tuned, using nanomaterials, to exhibit plasmonic or photoluminescent properties that can be exploited for sensing applications. We also describe several nanopaper configurations, including cuvettes, plates and spots that we printed or punched on BC. The platforms include a colorimetric-based sensor based on nanopaper containing embedded silver and gold nanoparticles; a photoluminescent-based sensor, comprising CdSe@ZnS quantum dots conjugated to nanopaper; and a potential up-conversion sensing platform constructed from nanopaper functionalized with NaYF
4 :Yb3+@Er3+&SiO2 nanoparticles. We have explored modulation of the plasmonic or photoluminescent properties of these platforms using various model biologically relevant analytes. Moreover, we prove that BC is and advantageous preconcentration platform that facilitates the analysis of small volumes of optically active materials ∼4 μ). We are confident that these platforms will pave the way to optical (bio)sensors or theranostic devices that are simple, transparent, flexible, disposable, lightweight, miniaturized and perhaps wearable. © 2015 American Chemical Society.
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Nanoparticle-based lateral flow biosensors
Quesada-González D., Merkoçi A. Biosensors and Bioelectronics; 73: 47 - 63. 2015. 10.1016/j.bios.2015.05.050. IF: 6.409
Lateral flow biosensors (LFBs) are paper-based devices which permit the performance of low-cost and fast diagnostics with good robustness, specificity, sensitivity and low limits of detection. The use of nanoparticles (NPs) as labels play an important role in the design and fabrication of a lateral flow strip (LFS). The choice of NPs and the corresponding detection method directly affect the performance of these devices. This review discusses aspects related to the application of different nanomaterials (e.g. gold nanoparticles, carbon nanotubes, quantum dots, up-converting phosphor technologies, and latex beads, between others) in LFBs. Moreover, different detection methods (colorimetric, fluorescent, electrochemical, magnetic, etc.) and signal enhancement strategies (affording secondary reactions or modifying the architecture of the LFS) as well as the use of devices such as smartphones to mediate the response of LFSs will be analyzed. © 2015 Elsevier B.V.
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Nanoparticle/nanochannels-based electrochemical biosensors
Espinoza-Castañeda M., de la Escosura-Munñiz A., Merkoçi A. NanoScience and Technology; 96: 205 - 223. 2015. 10.1007/978-3-319-14406-1_9. IF: 0.000
The purpose of this chapter is to provide a general comprehensive overview on the latest trends in the development of nanoparticle/nanochannelsbased electrochemical biosensors. Given the importance of nanoparticles, some general considerations about their use in biosensors are given before focusing on nanochannels-based electrochemical biosensing systems. A detailed description of representative and recent works covering the main nanochannel arrays fabrication techniques and their application in electrochemical biosensing systems is also given. The combination of nanochannel array sensing capability with the known advantages of nanoparticles in immunosensing is shown as an ideal approach for the diagnostic of proteins and DNA. As conclusion, the integration of nanochannel arrays with electrochemical transducers (ex. screen-printed electrode) seems to be one of the most important challenges in the development of robust sensing devices that may bring electrochemical/nanochannel-based biosensing technology to the market. © Springer International Publishing Switzerland 2015.
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Nanoparticles-based nanochannels assembled on a plastic flexible substrate for label-free immunosensing
de la Escosura-Muñiz A., Espinoza-Castañeda M., Hasegawa M., Philippe L., Merkoçi A. Nano Research; 8 (4): 1180 - 1188. 2015. 10.1007/s12274-014-0598-5. IF: 7.010
A novel, cheap, disposable and single-use nanoparticles-based nanochannel platform assembled on a flexible substrate for label-free immunosensing is presented. This sensing platform is formed by the dip-coating of a homogeneous and assembled monolayer of carboxylated polystyrene nanospheres (PS, 200 and 500 nm-sized) onto the working area of flexible screen-printed indium tin oxide/polyethylene terephthalate (ITO/PET) electrodes. The spaces between the self-assembled nanospheres generate well-ordered nanochannels, with inter-PS particles distances of around 65 and 24 nm respectively. The formed nanochannels are used for the effective immobilization of antibodies and subsequent protein detection based on the monitoring of [Fe(CN)6]4− flow through diffusion and the decrease in the differential pulse voltammetric signal upon immunocomplex formation. The obtained sensing system is nanochannel-size dependent and allows human immunoglobulin G (IgG) (chosen as a model analyte) to be detected at levels of 580 ng/mL. The system also exhibits an excellent specificity against other proteins present in real samples and shows good performance with a human urine sample. The developed device represents an integrated and simple biodetection system which overcomes many of the limitations of previously reported nanochannels-based approaches and can be extended in the future to several other immuno and DNA detection systems. © 2014, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
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On-the-Spot Immobilization of Quantum Dots, Graphene Oxide, and Proteins via Hydrophobins
Gravagnuolo A.M., Morales-Narváez E., Matos C.R.S., Longobardi S., Giardina P., Merkoçi A. Advanced Functional Materials; 25 (38): 6084 - 6092. 2015. 10.1002/adfm.201502837. IF: 11.805
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self-assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self-assembling of Vmh2 at liquid-solid interfaces is achieved (in 2 min). The Vmh2-coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti-immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self-assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications. Immobilization of optically active nanomaterials and proteins (particularly, cadmium telluride quantum dots, graphene oxide, antibodies, and bovine serum albumin) on glass is achieved using a Janus-faced fungal protein, hydrophobin Vmh2, which is extracted from Pleurotus ostreatus. The proposed glass nanobiofunctionalization is fast, easily scalable, and environmental friendly, which is appealing for new bioanalytical and nanobioenabled applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Photoluminescent Lateral-Flow Immunoassay Revealed by Graphene Oxide: Highly Sensitive Paper-Based Pathogen Detection
Morales-Narváez E., Naghdi T., Zor E., Merkoçi A. Analytical Chemistry; 87 (16): 8573 - 8577. 2015. 10.1021/acs.analchem.5b02383. IF: 5.636
A paper-based lateral flow immunoassay for pathogen detection that avoids the use of secondary antibodies and is revealed by the photoluminescence quenching ability of graphene oxide is reported. Escherichia coli has been selected as a model pathogen. The proposed device is able to display a highly specific and sensitive performance with a limit of detection of 10 CFU mL-1 in standard buffer and 100 CFU mL-1 in bottled water and milk. This low-cost disposable and easy-to-use device will prove valuable for portable and automated diagnostics applications. © 2015 American Chemical Society.
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Triple lines gold nanoparticle-based lateral flow assay for enhanced and simultaneous detection of Leishmania DNA and endogenous control
Rivas L., de la Escosura-Muñiz A., Serrano L., Altet L., Francino O., Sánchez A., Merkoçi A. Nano Research; 8 (11): 3704 - 3714. 2015. 10.1007/s12274-015-0870-3. IF: 7.010
A novel triple lines lateral-flow assay (LFA) with enhanced sensitivity for the detection of Leishmania infantum DNA in dog blood samples was designed and successfully applied. The enhanced LFA methodology takes advantage of the gold nanoparticle tags (AuNPs) conjugated to polyclonal secondary antibodies, which recognize anti-FITC antibodies. The polyclonal nature of the secondary antibodies allows for multiple binding to primary antibodies, leading to enhanced AuNP plasmonics signal. Furthermore, endogenous control consisting of the amplified dog 18S rRNA gene was introduced to avoid false negatives. Using this strategy, 0.038 spiked Leishmania parasites per DNA amplification reaction (1 parasite/100 μL of DNA sample) were detected. Detection limit of LFA was found to be lower than that of the conventional techniques. In summary, our novel LFA design is a universal and simple sensing alternative that can be extended to several other biosensing scenarios. [Figure not available: see fulltext.] © 2015, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
2014
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Alzheimer Disease Biomarker Detection Through Electrocatalytic Water Oxidation Induced by Iridium Oxide Nanoparticles
Rivas, L.; de la Escosura-Muñiz, A.; Pons, J.; Merkoçi, A. Electroanalysis; 26 (6): 1287 - 1294. 2014. 10.1002/elan.201400027. IF: 2.502
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An inkjet-printed field-effect transistor for label-free biosensing
Medina-Sánchez, M.; Martínez-Domingo, C.; Ramon, E.; Merkoçi, A. Advanced Functional Materials; 24 (40): 6291 - 6302. 2014. 10.1002/adfm.201401180. IF: 10.439
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An integrated phenol 'sensoremoval' microfluidic nanostructured platform
Mayorga-Martinez, C.C.; Hlavata, L.; Miserere, S.; López-Marzo, A.; Labuda, J.; Pons, J.; Merkoçi, A. Biosensors and Bioelectronics; 55: 355 - 359. 2014. 10.1016/j.bios.2013.12.035. IF: 6.451
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Electroanalysis-Based Clinical Diagnostics
Merkoçi, A. Electroanalysis; 26 (6): 1110. 2014. 10.1002/elan.201410132. IF: 2.502
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Electrocatalytic tuning of biosensing response through electrostatic or hydrophobic enzyme-graphene oxide interactions
Baptista-Pires, L.; Pérez-López, B.; Mayorga-Martinez, C.C.; Morales-Narváez, E.; Domingo, N.; Esplandiu, M.J.; Alzina, F.; Torres, C.M.S.; Merkoçi, A. Biosensors and Bioelectronics; 61: 655 - 662. 2014. 10.1016/j.bios.2014.05.028. IF: 6.451
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Electrochemical antibody-aptamer assay for VEGF cancer biomarker detection
Ravalli A.; Marrazza G.; Rivas L.; De La Escosura-Muniz A.; Merkoci A. Lecture Notes in Electrical Engineering; 268 LNEE: 175 - 178. 2014. . IF: 0.000
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Extremely fast and high Pb2+ removal capacity using a nanostructured hybrid material
Lópezmarzo, A.M.; Pons, J.; Merkoçi, A. Journal of Materials Chemistry A; 2 (23): 8766 - 8772. 2014. 10.1039/c4ta00985a. IF: 0.000
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Graphene/Silicon heterojunction schottky diode for vapors sensing using impedance spectroscopy
Fattah, A.; Khatami, S.; Mayorga-Martinez, C.C.; Medina-Sánchez, M.; Baptista-Pires, L.; Merkoçi, A. Small; 10 (20): 4193 - 4199. 2014. 10.1002/smll.201400691. IF: 7.514
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Improving sensitivity of gold nanoparticle-based lateral flow assays by using wax-printed pillars as delay barriers of microfluidics
Rivas, L.; Medina-Sánchez, M.; De La Escosura-Muñiz, A.; Merkoçi, A. Lab on a Chip - Miniaturisation for Chemistry and Biology; 14 (22): 4406 - 4414. 2014. 10.1039/c4lc00972j. IF: 5.748
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Iridium oxide nanoparticle induced dual catalytic/inhibition based detection of phenol and pesticide compounds
Mayorga-Martinez, C.C.; Pino, F.; Kurbanoglu, S.; Rivas, L.; Ozkan, S.A.; Merkoçi, A. Journal of Materials Chemistry B; 2 (16): 2233 - 2239. 2014. 10.1039/c3tb21765e. IF: 0.000
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Micromotor enhanced microarray technology for protein detection
Morales-Narváez, E.; Guix, M.; Medina-Sánchez, M.; Mayorga-Martinez, C.C.; Merkoçi, A. Small; 10 (13): 2542 - 2548. 2014. 10.1002/smll.201303068. IF: 7.514
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Nano/Micromotors in (Bio)chemical science applications
Guix, M.; Mayorga-Martinez, C.C.; Merkoçi, A. Chemical Reviews; 114 (12): 6285 - 6322. 2014. 10.1021/cr400273r. IF: 45.661
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On-chip magneto-immunoassay for Alzheimer's biomarker electrochemical detection by using quantum dots as labels
Medina-Sánchez, M.; Miserere, S.; Morales-Narváez, E.; Merkoçi, A. Biosensors and Bioelectronics; 54: 279 - 284. 2014. 10.1016/j.bios.2013.10.069. IF: 6.451
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Simple on-plastic/paper inkjet-printed solid- state Ag/AgCl pseudo-reference electrode
da Silva, E.T. S. G.; Miserere, S.; Kubota, L.T.; Merkoçi, A. Analytical Chemistry; 86 (21): 10531 - 10534. 2014. . IF: 5.825
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Supramolecular interaction of dopamine with ß-cyclodextrin: An experimental and theoretical electrochemical study
Palomar-Pardavé, M.; Corona-Avendaño, S.; Romero-Romo, M.; Alarcón-Angeles, G.; Merkoçi, A.; Ramírez-Silva, M.T. Journal of Electroanalytical Chemistry; 717-718: 103 - 109. 2014. 10.1016/j.jelechem.2014.01.002. IF: 2.871
2013
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All-integrated and highly sensitive paper based device with sample treatment platform for Cd2+ immunodetection in drinking/tap waters
López Marzo, A.M.; Pons, J.; Blake, D.A.; Merkoçi, A. Analytical Chemistry; 85 (7): 3532 - 3538. 2013. 10.1021/ac3034536. IF: 5.695
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Assembly of gold nanorods for highly sensitive detection of mercury ions
Placido, T.; Comparelli, R.; Striccoli, M.; Agostiano, A.; Merkoci, A.; Curri, M.L. IEEE Sensors Journal; 13 (8): 2834 - 2841. 2013. 10.1109/JSEN.2013.2257738. IF: 1.475
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Bismuth nanoparticles for phenolic compounds biosensing application
Mayorga-Martinez, C.C.; Cadevall, M.; Guix, M.; Ros, J.; Merkoçi, A. Biosensors and Bioelectronics; 40: 57 - 62. 2013. 10.1016/j.bios.2012.06.010. IF: 5.437
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Casein modified gold nanoparticles for future theranostic applications
Espinoza-Castañeda, M.; de la Escosura-Muñiz, A.; González-Ortiz, G.; Martín-Orúe, S.M.; Pérez, J.F.; Merkoçi, A. Biosensors and Bioelectronics; 40: 271 - 276. 2013. 10.1016/j.bios.2012.07.042. IF: 5.437
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Deprotonation mechanism and acidity constants in aqueous solution of flavonols: A combined experimental and theoretical study
Álvarez-Diduk, R.; Ramírez-Silva, M.T.; Galano, A.; Merkoçi, A. Journal of Physical Chemistry B; 117 (41): 12347 - 12359. 2013. 10.1021/jp4049617. IF: 3.607
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Design, preparation, and evaluation of a fixed-orientation antibody/gold-nanoparticle conjugate as an immunosensing label
Parolo, C.; De La Escosura-Muñiz, A.; Polo, E.; Grazú, V.; De La Fuente, J.M.; Merkoçi, A. ACS applied materials & interfaces; 5 (21): 10753 - 10759. 2013. 10.1021/am4029153. IF: 5.008
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Electrochemical detection of Salmonella using gold nanoparticles
Afonso, A.S.; Pérez-López, B.; Faria, R.C.; Mattoso, L.H.C.; Hernández-Herrero, M.; Roig-Sagués, A.X.; Maltez-da Costa, M.; Merkoçi, A. Biosensors and Bioelectronics; 40: 121 - 126. 2013. 10.1016/j.bios.2012.06.054. IF: 5.437
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Enhanced lateral flow immunoassay using gold nanoparticles loaded with enzymes
Parolo, C.; de la Escosura-Muñiz, A.; Merkoçi, A. Biosensors and Bioelectronics; 40: 412 - 416. 2013. 10.1016/j.bios.2012.06.049. IF: 5.437
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Exploring release and recovery of nanomaterials from commercial polymeric nanocomposites
Busquets-Fité, M.; Fernandez, E.; Janer, G.; Vilar, G.; Vázquez-Campos, S.; Zanasca, R.; Citterio, C.; Mercante, L.; Puntes, V. Journal of Physics: Conference Series; 429: 1. 2013. 10.1088/1742-6596/429/1/012048. IF: 0.000
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Gold nanoparticles decorated with a ferrocene derivative as a potential shift-based transducing system of interest for sensitive immunosensing
Mars, A.; Parolo, C.; Raouafi, N.; Boujlel, K.; Merkoçi, A. Journal of Materials Chemistry B; 1 (23): 2951 - 2955. 2013. 10.1039/c3tb20503g. IF: 6.108
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Graphene oxide as a pathogen-revealing agent: Sensing with a digital-like response
Morales-Narváez, E.; Hassan, A.-R.; Merkoçi, A. Angewandte Chemie - International Edition; 52 (51): 13779 - 13783. 2013. 10.1002/anie.201307740. IF: 13.734
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High sensitive gold-nanoparticle based lateral flow Immunodevice for Cd2+ detection in drinking waters
López-Marzo, A.M.; Pons, J.; Blake, D.A.; Merkoçi, A. Biosensors and Bioelectronics; 47: 190 - 198. 2013. 10.1016/j.bios.2013.02.031. IF: 5.437
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Ion-directed assembly of gold nanorods: A strategy for mercury detection
Placido, T.; Aragay, G.; Pons, J.; Comparelli, R.; Curri, M.L.; Merkoçi, A. ACS applied materials & interfaces; 5 (3): 1084 - 1092-1092. 2013. 10.1021/am302870b. IF: 5.008
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Micromotor-based lab-on-chip immunoassays
García, M.; Orozco, J.; Guix, M.; Gao, W.; Sattayasamitsathit, S.; Escarpa, A.; Merkoçi, A.; Wang, J. Nanoscale; 5 (4): 1325 - 1331-1331. 2013. 10.1039/c2nr32400h. IF: 6.233
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Multifunctional system based on hybrid nanostructured rod formation, for sensoremoval applications of Pb2+ as a model toxic metal
López-marzo, A.M.; Pons, J.; Merkoçi, A. Journal of Materials Chemistry A; 1 (43): 13532 - 13541-13541. 2013. 10.1039/c3ta12986a. IF: 6.108
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Nano-assembled supramolecular films from chitosan-stabilized gold nanoparticles and cobalt(II) phthalocyanine
Silva, A.T.B.; Coelho, A.G.; Da Lopes, L.C.S.; Martins, M.V.A.; Crespilho, F.N.; Merkoçi, A.; Da Silva, W.C. Journal of the Brazilian Chemical Society; 24 (8): 1237 - 1245-1245. 2013. 10.5935/0103-5053.20130157. IF: 1.283
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Nanochannels for diagnostic of thrombin-related diseases in human blood
de la Escosura-Muñiz, A.; Chunglok, W.; Surareungchai, W.; Merkoçi, A. Biosensors and Bioelectronics; 40: 24 - 31. 2013. 10.1016/j.bios.2012.05.021. IF: 5.437
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Nanomaterials for bio-functionalized electrodes: Recent trends
Walcarius, A.; Minteer, S.D.; Wang, J.; Lin, Y.; Merkoçi, A. Journal of Materials Chemistry B; 1 (38): 4878 - 4908-4908. 2013. 10.1039/c3tb20881h. IF: 6.108
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Nanoparticles Based Electroanalysis in Diagnostics Applications
Merkoçi, A. Electroanalysis; 25 (1): 15 - 27-27. 2013. 10.1002/elan.201200476. IF: 2.817
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Nanostructured CaCO3-poly(ethyleneimine) microparticles for phenol sensing in fluidic microsystem
Mayorga-Martinez, C.C.; Hlavata, L.; Miserere, S.; López-Marzo, A.; Labuda, J.; Pons, J.; Merkoçi, A. Electrophoresis; 34 (14): 2011 - 2016-2016. 2013. 10.1002/elps.201300056. IF: 3.261
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Paper-based electrodes for nanoparticles detection
Parolo, C.; Medina-Sánchez, M.; Montõn, H.; De La Escosura-Muñiz, A.; Merkoçi, A. Particle and Particle Systems Characterization; 30: 662 - 666. 2013. 10.1002/ppsc.201200124. IF: 0.000
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Paper-based nanobiosensors for diagnostics
Parolo, C.; Merkoçi, A. Chemical Society Reviews; 42: 450 - 457. 2013. 10.1039/c2cs35255a. IF: 24.892
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Screen-printed electrodes incorporated in a flow system for the decentralized monitoring of lead, cadmium and copper in natural and wastewater samples
Güell, R.; Fontàs, C.; Aragay, G.; Merkoçi, A.; Anticó, E. International Journal of Environmental Analytical Chemistry; 93: 872 - 883. 2013. 10.1080/03067319.2012.684049. IF: 1.240
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Simple paper architecture modifications lead to enhanced sensitivity in nanoparticle based lateral flow immunoassays
Parolo, C.; Medina-Sánchez, M.; De La Escosura-Muñiz, A.; Merkoçi, A. Lab on a Chip - Miniaturisation for Chemistry and Biology; 13 (3): 386 - 390-390. 2013. 10.1039/c2lc41144j. IF: 5.697
2012
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Analytical miniaturization and nanotechnologies
Merkoci, A.; Kutter, J.P. Lab on a Chip - Miniaturisation for Chemistry and Biology; 12: 1915 - 1916. 2012. .
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Bacterial Isolation by Lectin-Modified Microengines
Campuzano, S.; Orozco, J. ; Kagan, D.; Guix, M.; Gao, W. ; Sattayasamitsathit, S. ; Claussen, J. C.; Merkoçi, A. ; Wang, J. Nano Letters; 12: 396 - 401. 2012. .
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Bimetallic Nanowires as Electrocatalyst for Nonenzymatic Real Time Impedancimetric Detection of Glucose
Mayorga-Martinez, C.C.; Guix, M.; Madrid, R.E; Merkoçi, A. Chemical Communications; 48: 1686 - 1688. 2012. .
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Cancer detection using nanoparticle-based sensors
Turner, A.; Merkoçi, A. ; Perfezou, M. Chemical Society Reviews; 41: 2606 - 2622. 2012. .
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Carbon nanotubes and graphene in analytical sciences
Pérez-López, B.; Merkoçi, A. Mikrochimica Acta; 179: 1 - 16. 2012. 10.1007/s00604-012-0871-9.
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Controlled formation of nanostructured CaCO3¿PEI microparticles with high biofunctionalizing capacity
López-Marzo, A.; Pons, J.; Merkoçi, A. Journal of Materials Chemistry; 22: 15326 - 15335. 2012. .
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Detection of circulating cancer cells using electrocatalytic gold nanoparticles
Maltez-Da Costa, M.; De La Escosura-Muñiz, A.; Nogués, C.; Barrios, L.; Ibáñez, E.; Merkoçi, A. Small; 8: 3605 - 3612. 2012. 10.1002/smll.201201205.
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Graphene Oxide as an Optical Biosensing Platform
Morales-Narváez, E.; Merkoçi, A. Advanced Materials; 24: 3298 - 3308. 2012. .
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Medium Dependent Dual Turn-On/Turn-Off Fluorescence System for Heavy Metal Ions Sensing
Aragay, G.; Alarcón, G.; Pons, J.; Font-Bardía, M.; Merkoçi, A. Journal of Physical Chemistry C; 116 (2): 1987 - 1994. 2012. 10.1021/jp210687v.
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Nanochannels preparation and application in biosensing
De La Escosura-Muñiz, A.; Merkoçi, A. ACS Nano; 6: 7556 - 7583. 2012. 10.1021/nn301368z.
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Nanomaterials and lab-on-a-chip technologies
Medina-Sánchez, M.; Miserere, S.; Merkoçi, A. Lab on a Chip - Miniaturisation for Chemistry and Biology; 12: 1932 - 1943. 2012. .
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Nanomaterials application in electrochemical detection of heavy metals
Aragay, G.; Merkoçi, A. Electrochimica Acta; 84: 49 - 61. 2012. .
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Nanomaterials Based Electrochemical Sensing Applications for Safety and Security
Marín, S.; Merkoçi, A. Electroanalysis; 24: 459 - 469. 2012. .
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Nanomaterials for Sensing and Destroying Pesticides
Aragay, G.; Pino, F.; Merkoçi, A. Chemical Reviews; 112: 5317 - 5338. 2012. .
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Nanoparticles for Proteins and Cells Detection. Novel Tools for Clinical Diagnostics.
Merkoçi, A. GIT Laboratory Journal Europe; 2012. .
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On-chip electrochemical detection of CdS quantum dots using normal and multiple recycling flow through modes
Medina-Sánchez, M.; Miserere, S.; Marín, S.; Aragay, G.; Merkoçi, A. Lab on a Chip - Miniaturisation for Chemistry and Biology; 12: 2000 - 2005. 2012. .
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Rapid and highly sensitive detection of mercury ions using a fluorescence-based paper test strip with an N-alkylaminopyrazole ligand as a receptor
Aragay, G.; Montón, H.; Pons, J.; Font-Bardíac, M.; Merkoçi, M. Journal of Materials Chemistry; 22: 5978 - 5983. 2012. .
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Signal enhancement in antibody microarrays using quantum dots nanocrystals: Application to potential Alzheimer¿s disease biomarker screening
Morales-Narváez, E.; Montón, H.; Fomicheva, A.; Merkoçi, A. Analytical Chemistry; 84(15): 6821 - 6827. 2012. .
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Simple Forster resonance energy transfer evidence for the ultrahigh quantum dot quenching efficiency by graphene oxide compared to other carbon structures
Morales-Narváez, E.; Pérez-López, B.; Baptista Pires, L.; Merkoçi, A. Carbon; 50(8): 2987 - 2993. 2012. .
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Simple monitoring of cancer cells using nanoparticles
Maltez-Da Costa, M.; De La Escosura-Muñiz, A.; Nogués, C.; Barrios, L.; Ibáñez, E.; Merkoçi, A. Nano Letters; 12: 4164 - 4171. 2012. 10.1021/nl301726g.
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Superhydrophobic Alkanethiol-Coated Microsubmarines for Effective Removal of Oil
Guix, M.; Orozco, J.; García, M.; Gao, W.; Sattayasamitsathit, S.; Merkoçi, A.; Escarpa, A.; Wang, J. ACS Nano; 6(5): 4445 - 4451. 2012. DOI: 10.1021/nn301175b.
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The use of quantum dots for immunochemistry applications
Montón, H.; Roldán, M.; Merkoçi, A.; Rossinyol, E.; Castell, O.; Nogués, C. Methods in molecular biology (Clifton, N,J,); 906: 185 - 192. 2012. .
2011
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Electrochemical investigation of cellular uptake of quantum dots decorated with a proline-rich cell penetrating peptide
Marín, S.; Pujals, S.; Giralt, E.; Merkoçi, A. Bioconjugate Chemistry; 22: 180 - 185. 2011. 10.1021/bc100207w.
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Enhanced electrochemical detection of heavy metals at heated graphite nanoparticle -based screen-printed electrodes
Aragay, G.; Pons, J.; Merkoçi, A. Chemistry of Materials; 2011. .
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Magnetic and electrokinetic manipulations on a microchip device for bead-based immunosensing applications
Ambrosi, A.; Guix, M.; Merkoçi, A. Electrophoresis; 32: 861 - 869. 2011. 10.1002/elps.201000268.
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Nanomaterials based biosensors for food analysis applications
Pérez-López, B.; Merkoçi, A. Trends in Food Science and Technology; 22: 625 - 639. 2011. 10.1016/j.tifs.2011.04.001.
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Nanoparticles for the development of improved (bio)sensing systems
Pérez-López, B.; Merkoçi, A. Analytical and Bioanalytical Chemistry; 399: 1577 - 1590. 2011. 10.1007/s00216-010-4566-y.
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Recent trends in macro-, micro-, and nanomaterial-based tools and strategies for heavy-metal detection
Aragay, G.; Pons, J.; Merkoçi, A. Chemical Reviews; 111: 3433 - 3458. 2011. 10.1021/cr100383r.
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Size-dependent direct electrochemical detection of gold nanoparticles: Application in magnetoimmunoassays
De La Escosura-Muñiz, A.; Parolo, C.; Maran, F.; Mekoi, A. Nanoscale; 3: 3350 - 3356. 2011. 10.1039/c1nr10377f.
2010
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A Nanochannel/Nanoparticle-Based Filtering and Sensing Platform for Direct Detection of a Cancer Biomarker in Blood
de la Escosura-Muñiz, A.; Merkoçi, A. Small; 2010. .
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Aminopyrazole-Based Ligand Induces Gold Nanoparticle Formation and Remains Available for Heavy Metal Ions Sensing. A Simple ¿Mix and Detect¿ Approach
Aragay, G.; Pons, J.; Ros, J.; Merkoçi, A. Langmuir : the ACS journal of surfaces and colloids; 2010. .
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Aptamers based electrochemical biosensor for protein detection using carbon nanotubes platforms
Kara, P.; de la Escosura-Muñiz, A.; Maltez-da Costa, M.; Guix, M.; Ozsoz, M.; Merkoçi, A. Biosensors and Bioelectronics; 26: 1715 - 1718. 2010. 10.1016/j.bios.2010.07.090.
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Bismuth Film Combined with Screen-Printed Electrode as Biosensing Platform for Phenol Detection
Merkoçi, A.; Anik, U.; Çevik, S.; Çubukçu, M.; Guix, M. Electroanalysis; 2010. .
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Compact microcubic structures platform based on self-assembly
Prussian blue nanoparticles with highly tuneable conductivity
Cantanhêde Silva, W.; Guix, M.; Alarcón Angeles, G.; Merkoçi, A. Physical Chemistry Chemical Physics; 2010. .
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Electrochemical detection of proteins using nanoparticles: applications to diagnostics
de la Escosura-Muñiz, A.; Merkoçi, A. Expert Opinion on Medical Diagnostics; 2010. .
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Electrochemical quantification of gold nanoparticles based on their catalytic properties toward hydrogen formation: Application in magnetoimmunoassays
Costa, M.M.-D.; La Escosura-Muñiz, A.D.; Merkoçi, A. Electrochemistry Communications; 12: 1501 - 1504. 2010. 10.1016/j.elecom.2010.08.018.
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Enhanced gold nanoparticle based ELISA for a breast cancer biomarker
Ambrosi, A.; Airò, F.; Merkoçi, A. Analytical Chemistry; 82: 1151 - 1156. 2010. 10.1021/ac902492c.
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Enzyme entrapment by ß-cyclodextrin electropolymerization onto a carbon nanotubes-modified screen-printed electrode
Alarcón Ángeles, G. ; Guix, M. ; Silva, W.C.; Ramírez-Silva, M.T.; Palomar-Pardavé, M.; Romero-Romo, M.; Merkoçi, A. Biosensors and Bioelectronics; 2010. .
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Gold nanoparticle-based electrochemical magnetoimmunosensor for rapid detection of anti-hepatitis B virus antibodies in human serum
de la Escosura-Muñiz, A.; Maltez-da Costa, M.; Sánchez-Espinel, C.; Díaz-Freitas, B.; Fernández-Suarez, J.; González-Fernández, Á.; Merkoçi, A. Biosensors and Bioelectronics; 26: 1710 - 1714. 2010. 10.1016/j.bios.2010.07.069.
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Immunosensing using nanoparticles
De La Escosura-Muñiz, A.; Parolo, C.; Merkoçi, A. Materials Today; 13: 24 - 34. 2010. 10.1016/S1369-7021(10)70125-5.
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Label-free voltammetric immunosensor using a nanoporous membrane based platform
De La Escosura-Muñiz, A.; Merkoçi, A. Electrochemistry Communications; 12: 859 - 863. 2010. 10.1016/j.elecom.2010.04.007.
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Magnetic Nanoparticles Modified with Carbon Nanotubes for Electrocatalytic Magnetoswitchable Biosensing Applications
Pérez-López, B.; Merkoçi, A. Advanced Functional Materials; 2010. 10.1002/adfm.201001306.
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Nanoparticle based enhancement of electrochemical DNA hybridization signal using nanoporous electrodes
De La Escosura-Muñiz, A.; Merkoçi, A. Chemical Communications; 46: 9007 - 9009. 2010. 10.1039/c0cc02683b.
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Nanoparticles-based strategies for DNA, protein and cell sensors
Merkoçi, A. Biosensors and Bioelectronics; 26: 1164 - 1177. 2010. 10.1016/j.bios.2010.07.028.
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Stable and sensitive flow-through monitoring of phenol using a carbon nanotube based screen printed biosensor
Alarcón, G.; Guix, M.; Ambrosi, A.; Ramirez Silva, M.T. ; Palomar Pardave, M.E.; Merkoçi, A. Nanotechnology; 2010. .
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Structural characterization by confocal laser scanning microscopy and electrochemical study of multi-walled carbon nanotube tyrosinase matrix for phenol detection
Guix, M.; Pérez-López, B.; Sahin, M.; Roldán, M.; Ambrosi, A.; Merkoçi, A. The Analyst; 2010. .
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Use of Sequential Injection Analysis to construct a potentiometric electronic tongue: Application to the multidetermination of heavy metals
Mimendia, A.; Legin, A.; Merkoçi, A.; del Valle, M. Sensors and Actuators, B: Chemical; 146: 420 - 426. 2010. 10.1016/j.snb.2009.11.027.
2009
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Controlling the electrochemical deposition of silver onto gold nanoparticles: reducing interferences and increasing the sensitivity of magnetoimmuno assays
de la Escosura, A. ; Máltez, M.; Merkoçi, A. Biosensors and Bioelectronics; 24: 2475 - 2482. 2009. .
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Direct electrochemical stripping detection of cystic fibrosis related DNA linked through cadmium sulphide quantum dots
Marín, S. ; Merkoçi, A. Nanotechnology; 2009. .
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Electrochemical analysis with nanoparticle based biosystems
de la Escosura-Muñiz, A.; Ambrosi, A.; Merkoçi, A. TrAC - Trends in Analytical Chemistry; 27 (7): 568 - 584. 2009. 10.1016/j.trac.2008.05.008.
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ICP-MS- a powerful technique for quantitative determination of gold nanoparticles without previous dissolving
R. Allabashi; W. Stach; A. de la Escosura; L. Liste; A. Merkoçi Journal of Nanoparticle Research; 11: 2003 - 2011. 2009. 10.1007/s11051-008-9561-2.
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Improvement of the electrochemical detection of catechol by the use of a carbon nanotube based biosensor
B. Pérez; A. Merkoçi The Analyst; 134: 60 - 64. 2009. 10.1039/b808387h.
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Lab-on-a-chip for ultrasensitive detection of carbofuran by enzymatic inhibition with replacement of enzyme using magnetic beads
X. Llopis; M. Pumera; S. Alegret; A. Merkoçi Lab on a Chip - Miniaturisation for Chemistry and Biology; 9: 213 - 218. 2009. 10.1039/B816643A.
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Permeability improvement of electropolymerized polypyrrole films in water using magnetic hydrophilic microbeads
S. Cosnier; S. N. Ding; A. Pellissier; K. Gorgy; M. Holzinger; B. Pérez López; A. Merkoçi Electroanalysis; 21 (7): 887 - 890. 2009. 10.1002/elan.200804484 .
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Plasma-activated multi-walled carbon nanotube-polystyrene composite substrates for biosensing
Fernández-Sánchez, C.; Pellicer, E.; Orozco, J.; Jiménez-Jorquera, C.; Lechuga, L.M.; Mendoza, E. Nanotechnology; 20 2009. 10.1088/0957-4484/20/33/335501.
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Rapid identification and quantification of tumor cells using an electrocatalytic method based on gold nanoparticles
De La Escosura-Muñiz, A.; Sánchez-Espinel, C.; Díaz-Freitas, B.; González-Fernández, Á.; Maltez-Da Costa, M.; Merkoçi, A. Analytical Chemistry; 81: 10268 - 10274. 2009. 10.1021/ac902087k.
2008
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A Carbon Nanotube PVC Based Matrix Modified with Glutaraldehyde Suitable for Biosensor Applications
Briza Pérez; Joan Sola; Salvador Alegret; Arben Merkoçi Electroanalysis; 6: 603 - 610. 2008. 10.1002/elan.200704119.
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Enhanced host guest electrochemical recognition of dopamine using cyclodextrin in the presence of carbon nanotubes
G. Alarcon Angeles; B. Pérez López; M. Palomar-Pardave; M. T. Ramírez-Silva; S. Alegret; A. Merkoçi Carbon; 46 (6): 898 - 906. 2008. 10.1016/j.carbon.2008.02.025.
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Sensitive and stable monitoring of lead and cadmium in seawater using screen-printed electrode and electrochemical stripping analysis
Raquel Güell; Gemma Aragay; Clàudia Fontàs; Enriqueta Anticó; Arben Merkoçi Analytical Chemistry; 627: 219 - 224. 2008. 10.1016/j.aca.2008.08.017.
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Silver, gold and the corresponding core shell nanoparticles: synthesis and characteritzation
Fraser Douglas; Ramon Yanez; Josep Ros; Sergio Marín; Alfredo de la Escosura; Salvador Alegret; Arben Merkoçi Journal of Nanoparticle Research; 10: 97 - 106. 2008. 10.1007/s11051-008-9374-3.
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The Usage of Bismuth Film Electrode as Transducer in Glucose Biosensing
Ülkü An¿k (K¿rgöz); Suna Timur; Meliha Çubukçu; Arben Merkoçi Mikrochimica Acta; 160: 269 - 273. 2008. 10.1007/s00604-007-0868-y.
2007
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Carbon nanofiber vs. carbon microparticles as modifiers of glassy carbon and gold electrodes applied in electrochemical sensing of NADH
Briza Pérez; Manel del Valle; Salvador Alegret; Arben Merkoçi Talanta; 74: 398 - 404. 2007. .
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Carbon nanotube composite as novel platform for microbial biosensor
Ülkü A. Kirgoz; Suna Timur; Dilek Odaci; Briza Pérez; Salvador Alegret; Arben Merkoçi Electroanalysis; 19: 893 - 898. 2007. 10.1002/elan.200603786.
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Carbon nanotube detectors for microchip CE: Comparative study of single-wall and multiwall carbon nanotube, and graphite powder films on glassy carbon, gold, and platinum electrode surfaces
Martin Pumera; Arben Merkoçi; Salvador Alegret Electrophoresis; 28: 1274 - 1280. 2007. 10.1002/elps.200600632.
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Detection of cadmium sulphide nanoparticles by using screen-printed electrodes and a handheld device
Arben Merkoçi; Luiz Humberto Marcolino-Junior; Sergio Marín; Orlando Fatibello-Filho; Salvador Alegret. Nanotechnology; 18: 35502. 2007. 10.1088/0957-4484/18/3/035502.
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DNA hybridization sensor based on aurothiomalate electroactive label on glassy carbon electrodes
De la Escosura Muñiz A.; González García M.B.; Costa García A. Biosensors and Bioelectronics; 22 (6): 1048 - 1054. 2007. 10.1016/j.bios.2006.04.024.
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Double-Codified Gold Nanolabels for Enhanced Immunoanalysis
Adriano Ambrosi; Maria Teresa Castañeda; Anthony J. Killard; Malcolm R. Smyth; Salvador Alegret; Arben Merkoçi Analytical Chemistry; 79 (14): 5232 - 5240. 2007. 10.1021/ac070357m.
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Electrochemical biosensing with nanoparticles (Invited review for the Minireview Series Nanobiotechnology by Itamar Willner)
Arben Merkoçi FEBS Journal; 274: 310 - 316. 2007. 10.1111/j.1742-4658.2006.05603.x.
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Electrochemical genosensors for biomedical applications based on gold nanoparticles
M.T. Castañeda; A. Merkoçi; M. Pumera; S. Alegret Biosensors and Bioelectronics; 22: 1961 - 1967. 2007. 10.1016/j.bios.2006.08.031,.
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Electrochemical sensing of DNA using gold nanoparticles
M.T.Castañeda; S.Alegret; A.Merkoçi Electroanalysis; 19: 743 - 753. 2007. 10.1002/elan.200603784.
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Nanobiomaterials in Electroanalysis
A. Merkoçi Electroanalysis; 2007. .