Staff directory Claudio Parolo

Claudio Parolo

Senior Postdoctoral Researcher
Nanobioelectronics and Biosensors



  • 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.

  • 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.

  • 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.


  • 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.


  • 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.


  • 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


  • 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.

  • 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.


  • Electrochemical DNA sensors based on nanoparticles

    Parolo C., De La Escosura-Muñiz A., Merkoçi A. Electrochemical Biosensors; : 195 - 222. 2014. .

    [No abstract available]