ICN2 Publications

2021

  • A Direct Z-Scheme for the Photocatalytic Hydrogen Production from a Water Ethanol Mixture on CoTiO3/TiO2Heterostructures

    Xing C., Liu Y., Zhang Y., Wang X., Guardia P., Yao L., Han X., Zhang T., Arbiol J., Soler L., Chen Y., Sivula K., Guijarro N., Cabot A., Llorca J. ACS Applied Materials and Interfaces; 13 (1): 449 - 457. 2021. 10.1021/acsami.0c17004. IF: 8.758

    Supramolecular NanoChemistry and Materials | Oxide Nanophysics | Advanced Electron Nanoscopy

    Photocatalytic H2 evolution from ethanol dehydrogenation is a convenient strategy to store solar energy in a highly valuable fuel with potential zero net CO2 balance. Herein, we report on the synthesis of CoTiO3/TiO2 composite catalysts with controlled amounts of highly distributed CoTiO3 nanodomains for photocatalytic ethanol dehydrogenation. We demonstrate these materials to provide outstanding hydrogen evolution rates under UV and visible illumination. The origin of this enhanced activity is extensively analyzed. In contrast to previous assumptions, UV-vis absorption spectra and ultraviolet photoelectron spectroscopy (UPS) prove CoTiO3/TiO2 heterostructures to have a type II band alignment, with the conduction band minimum of CoTiO3 below the H2/H+ energy level. Additional steady-state photoluminescence (PL) spectra, time-resolved PL spectra (TRPLS), and electrochemical characterization prove such heterostructures to result in enlarged lifetimes of the photogenerated charge carriers. These experimental evidence point toward a direct Z-scheme as the mechanism enabling the high photocatalytic activity of CoTiO3/TiO2 composites toward ethanol dehydrogenation. In addition, we probe small changes of temperature to strongly modify the photocatalytic activity of the materials tested, which could be used to further promote performance in a solar thermophotocatalytic reactor. ©


  • Antibody cooperative adsorption onto AuNPs and its exploitation to force natural killer cells to kill HIV-infected T cells

    Astorga-Gamaza A., Vitali M., Borrajo M.L., Suárez-López R., Jaime C., Bastus N., Serra-Peinado C., Luque-Ballesteros L., Blanch-Lombarte O., Prado J.G., Lorente J., Pumarola F., Pellicer M., Falcó V., Genescà M., Puntes V., Buzon M.J. Nano Today; 36 (101056) 2021. 10.1016/j.nantod.2020.101056. IF: 16.907

    Inorganic Nanoparticles

    HIV represents a persistent infection which negatively alters the immune system. New tools to reinvigorate different immune cell populations to impact HIV are needed. Herein, a novel nanotool for the specific enhancement of the natural killer (NK) immune response towards HIV-infected T-cells has been developed. Bispecific Au nanoparticles (BiAb-AuNPs), dually conjugated with IgG anti-HIVgp120 and IgG anti-human CD16 antibodies, were generated by a new controlled, linker-free and cooperative conjugation method promoting the ordered distribution and segregation of antibodies in domains. The cooperatively-adsorbed antibodies fully retained the capabilities to recognize their cognate antigen and were able to significantly enhance cell-to-cell contact between HIV-expressing cells and NK cells. As a consequence, the BiAb-AuNPs triggered a potent cytotoxic response against HIV-infected cells in blood and human tonsil explants. Remarkably, the BiAb-AuNPs were able to significantly reduce latent HIV infection after viral reactivation in a primary cell model of HIV latency. This novel molecularly-targeted strategy using a bispecific nanotool to enhance the immune system represents a new approximation with potential applications beyond HIV. © 2020 The Authors


  • Assessing Nickel Titanium Binary Systems Using Structural Search Methods and Ab Initio Calculations

    Lang L., Payne A., Valencia-Jaime I., Verstraete M.J., Bautista-Hernández A., Romero A.H. Journal of Physical Chemistry C; 125 (2): 1578 - 1591. 2021. 10.1021/acs.jpcc.0c10453. IF: 4.189

    Nickel titanium, also know as nitinol, is a prototypical shape memory alloy, a property intimately linked to a phase transition in the microstructure, which allows the meso/macroscopic sample shape to be recovered after thermal cycling. Not much is known about the other alloys in this binary system, which prompted our computational investigation of other compositions. In this work, structures are found by probing the potential energy surfaces of NiTi binary systems using a minima hopping method, in combination with ab initio electronic structure calculations. We find stable structures in 34 different stoichiometries and calculate derived physical properties of the low energy phases. From the results of this analysis a new convex hull is formed that is lower in energy than those in the Materials Project and Open Quantum Materials Databases. Two previously unreported phases are discovered for the NiTi2 and Ni5Ti compositions, and two metastable states in NiTi and NiTi2 shows signs of negative linear compression and negative Poisson ratio, respectively. ©


  • Atomically dispersed Fe in a C2N Based Catalyst as a Sulfur Host for Efficient Lithium–Sulfur Batteries

    Liang Z., Yang D., Tang P., Zhang C., Jacas Biendicho J., Zhang Y., Llorca J., Wang X., Li J., Heggen M., David J., Dunin-Borkowski R.E., Zhou Y., Morante J.R., Cabot A., Arbiol J. Advanced Energy Materials; 11 (5, 2003507) 2021. 10.1002/aenm.202003507. IF: 25.245

    Advanced Electron Nanoscopy

    Lithium–sulfur batteries (LSBs) are considered to be one of the most promising next generation energy storage systems due to their high energy density and low material cost. However, there are still some challenges for the commercialization of LSBs, such as the sluggish redox reaction kinetics and the shuttle effect of lithium polysulfides (LiPS). Here a 2D layered organic material, C2N, loaded with atomically dispersed iron as an effective sulfur host in LSBs is reported. X-ray absorption fine spectroscopy and density functional theory calculations prove the structure of the atomically dispersed Fe/C2N catalyst. As a result, Fe/C2N-based cathodes demonstrate significantly improved rate performance and long-term cycling stability. Fe/C2N-based cathodes display initial capacities up to 1540 mAh g−1 at 0.1 C and 678.7 mAh g−1 at 5 C, while retaining 496.5 mAh g−1 after 2600 cycles at 3 C with a decay rate as low as 0.013% per cycle. Even at a high sulfur loading of 3 mg cm−2, they deliver remarkable specific capacity retention of 587 mAh g−1 after 500 cycles at 1 C. This work provides a rational structural design strategy for the development of high-performance cathodes based on atomically dispersed catalysts for LSBs. © 2020 Wiley-VCH GmbH


  • Coordination polymers nanoparticles for bioimaging

    Suárez-García S., Solórzano R., Novio F., Alibés R., Busqué F., Ruiz-Molina D. Coordination Chemistry Reviews; 432 (213716) 2021. 10.1016/j.ccr.2020.213716. IF: 15.637

    Nanostructured Functional Materials

    Early diagnosis of patient diseases is subjected to the appropriate use of bioimaging techniques. For this reason, the development of contrast agents that improve and enhance the response of current clinical imaging practices is a pressing concern. Non-invasive bioimaging techniques most often need specific probes to follow and measure biological routes in living systems. These molecular imaging agents must exhibit: I) a remarkable contrast effect, i.e. a high signal-to-noise ratio under real physiological conditions, II) pronounced in vivo stability under the effect of numerous enzymes or proteases present in serum or targeted tissue equilibrated with a fast clearance from healthy organs and III) low cost and eco-friendly production. To overcome current drawbacks that hindrance the full development of the different bioimaging techniques, several groups are exploring nanoparticles as contrast agents. In this scenario, coordination polymer nanoparticles have emerged as a handy platform offering predesigned unique advantages thanks to their chemical flexibility, structural diversity and tailoring skills. Indeed, these systems reveal high metal cargos, low toxicity and multifunctional character by adequately selecting the combination of metal ions and ligands. Moreover, in a reminiscent way of organic polymeric nanoparticles, coordination polymer nanoparticles have also demonstrated its ability to encapsulate therapeutic-active molecules, thus combining diagnostic and therapeutic functionalities, the so-called Theranostic nanomedicine. For all these reasons, the use of this family of nanoparticles as imaging contrast agents has attracted broad interest over the last years with numerous examples being reported. Herein, we review main accomplishments in the area grouped according to the used technology, including magnetic resonance imaging, computed tomography, optical imaging, radioimaging or photoacoustic imaging. © 2020 Elsevier B.V.


  • Encapsulation and sedimentation of nanomaterials through complex coacervation

    González-Monje P., Ayala García A., Ruiz-Molina D., Roscini C. Journal of Colloid and Interface Science; 589: 500 - 510. 2021. 10.1016/j.jcis.2020.12.067. IF: 7.489

    Nanostructured Functional Materials

    Hypothesis: Nanoparticles removal from seawage water is a health and environmental challenge, due to the increasing use of these materials of excellent colloidal stability. Herein we hypothesize to reach this objective through complex coacervation, a straightforward, low-cost process, normally accomplished with non-toxic and biodegradable macromolecules. Highly dense polymer-rich colloidal droplets (the coacervates) obtained from a reversible charge-driven phase separation, entrap suspended nanomaterials, allowing their settling and potential recovery. Experiments: In this work we apply this process to highly stable aqueous colloidal dispersions of different surface charge, size, type and state (solid or liquid). We systematically investigate the effects of the biopolymers excess and the nanomaterials concentration and charge on the encapsulation and sedimentation efficiency and rate. This strategy is also applied to real laboratory water-based wastes. Findings: Long-lasting colloidal suspensions are succesfully destabilized through coacervate formation, which ensures high nanomaterials encapsulation efficiencies (~85%), payloads and highly tranparent supernatants (%T ~90%), within two hours. Lower polymer excess induces faster clearance and less sediments, while preserving effective nanomaterials removal. Preliminary experiments also validate the method for the clearance of real water residuals, making complex coacervation a promising scalable, low-cost and ecofriendly alternative to concentrate, separate or recover suspended micro/nanomaterials from aqueous sludges. © 2020 Elsevier Inc.


  • Exploiting the lability of metal halide perovskites for doping semiconductor nanocomposites

    Calcabrini M., Genc A., Liu Y., Kleinhanns T., Lee S., Dirin D.N., Akkerman Q.A., Kovalenko M.V., Arbiol J., Ibañez M. ACS Energy Letters; : 581 - 587. 2021. 10.1021/acsenergylett.0c02448. IF: 19.003

    Supramolecular NanoChemistry and Materials | Oxide Nanophysics | Advanced Electron Nanoscopy

    Cesium lead halides have intrinsically unstable crystal lattices and easily transform within perovskite and nonperovskite structures. In this work, we explore the conversion of the perovskite CsPbBr3 into Cs4PbBr6 in the presence of PbS at 450 °C to produce doped nanocrystal-based composites with embedded Cs4PbBr6 nanoprecipitates. We show that PbBr2 is extracted from CsPbBr3 and diffuses into the PbS lattice with a consequent increase in the concentration of free charge carriers. This new doping strategy enables the adjustment of the density of charge carriers between 1019 and 1020 cm-3, and it may serve as a general strategy for doping other nanocrystal-based semiconductors. © XXXX American Chemical Society


  • Formation and evolution of the nanoparticle environmental corona: The case of Au and humic acid

    Barbero F., Mayall C., Drobne D., Saiz-Poseu J., Bastús N.G., Puntes V. Science of the Total Environment; 768 (144792) 2021. 10.1016/j.scitotenv.2020.144792. IF: 6.551

    Inorganic Nanoparticles

    Studying the behaviour of nanomaterials after their release into natural water is essential to understand the risk associated to their environmental exposure. In particular, the interaction and adsorption of dissolved organic matter onto nanoparticles strongly influence the behaviour and fate of nanomaterials in natural water systems. We herein study the interaction of Au and Ag nanoparticles and humic acids, the principal component of natural dissolved organic matter. Physicochemical characterization results showed the formation of an organic matter corona, consisting of two layers: a “hard” one, firmly bound to the nanoparticle surface, and a “soft” one, in dynamic equilibrium and, consequently, highly dependent on the media organic matter concentration. The extent of the electro-steric stabilization of the so called environmental corona depends on the size of the supramolecular association of humic acid (which depends on its hydrophilic and lipophilic moieties), the nanoparticle size, the total concentration of organic matter in the media, and the ratio between them. Interestingly, environmental coronas can eventually prevent Ca2+ and Mg2+ induced aggregation at concentrations range present in most of the freshwater bodies. The humic coating formed on top of the Au or control Ag nanoparticles presented a similar profile, but the corrodibility of Ag led to a more natural detachment of the corona. These results were further confirmed by exposing the nanoparticles to a model of natural water and standard mud (LUFA 2.2 dispersion). In the latter case, after several days, nanoparticle sedimentation was observed, which was attributed to interactions with macro organic and inorganic matter (fraction larger than particulate matter). © 2021 Elsevier B.V.


  • Functional and morphological changes induced in mytilus hemocytes by selected nanoparticles

    Auguste M., Mayall C., Barbero F., Hočevar M., Alberti S., Grassi G., Puntes V.F., Drobne D., Canesi L. Nanomaterials; 11 (2, 470): 1 - 16. 2021. 10.3390/nano11020470. IF: 4.324

    Inorganic Nanoparticles

    Nanoparticles (NPs) show various properties depending on their composition, size, and surface coating, which shape their interactions with biological systems. In particular, NPs have been shown to interact with immune cells, that represent a sensitive surveillance system of external and internal stimuli. In this light, in vitro models represent useful tools for investigating nano-bio-interactions in immune cells of different organisms, including invertebrates. In this work, the effects of selected types of NPs with different core composition, size and functionalization (custom-made PVP-AuNP and commercial nanopolystyrenes PS-NH2 and PS-COOH) were investigated in the hemocytes of the marine bivalve Mytilus galloprovincialis. The role of exposure medium was evaluated using either artificial seawater (ASW) or hemolymph serum (HS). Hemocyte morphology was investigated by scanning electron microscopy (SEM) and different functional parameters (lysosomal membrane stability, phagocytosis, and lysozyme release) were evaluated. The results show distinct morphological and functional changes induced in mussel hemocytes depending on the NP type and exposure medium. Mussel hemocytes may represent a powerful alternative in vitro model for a rapid pre-screening strategy for NPs, whose utilization will contribute to the understanding of the possible impact of environmental exposure to NPs in marine invertebrates. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Gadolinium-Incorporated Carbon Nanodots for T1-Weighted Magnetic Resonance Imaging

    Ji D.-K., Reina G., Liang H., Zhang D., Guo S., Ballesteros B., Ménard-Moyon C., Li J., Bianco A. ACS Applied Nano Materials; 2021. 10.1021/acsanm.0c02993. IF: 0.000

    Electron Microscopy Unit

    The design and development of contrast agents for magnetic resonance imaging (MRI) with improved chemical stability and higher contrasting capability for clinical translation compared to conventional contrast agents are still of great interest. In this study, a facile and universal approach was explored for controllable functionalization of red-emissive carbon nanodots (RCNDs) with diethylenetriaminepentaacetic anhydride (DTPA) for chelation of gadolinium. A series of accurate characterizations were used to control each step of the synthesis. The functionalization did not alter the band gap of the carbon nanodots, preserving their inherent far-red fluorescence. The as-prepared RCND-DTPA-Gd displayed a high colloidal stability with negligible Gd leakage. The nanodots also showed a better magnetic resonance relaxivity than commercial MRI agents. RCND-DTPA-Gd had good biocompatibility in vivo even at high doses. The systemically injected RCND-DTPA-Gd were found to be efficiently excreted through the renal route, a feature that further minimizes the potential toxicity risks. All these properties suggest that carbon nanodots can be well designed as efficient carriers of Gd, resulting in potential clinical tools as dual MRI/fluorescence functional probes for imaging applications. The approach described here could pave the pathway to a flexible strategy for the controllable functionalization of small-sized nanoparticles including carbon dots, rendering them more versatile. This work is expected to promote the future translation of carbon nanodots into clinical trials. © 2021 American Chemical Society.


  • Gold nanoparticles coated with polyvinylpyrrolidone and sea urchin extracellular molecules induce transient immune activation

    Alijagic A., Barbero F., Gaglio D., Napodano E., Benada O., Kofroňová O., Puntes V.F., Bastús N.G., Pinsino A. Journal of Hazardous Materials; 402 (123793) 2021. 10.1016/j.jhazmat.2020.123793. IF: 9.038

    Inorganic Nanoparticles

    We report that the immunogenicity of colloidal gold nanoparticles coated with polyvinylpyrrolidone (PVP–AuNPs) in a model organism, the sea urchin Paracentrotus lividus, can function as a proxy for humans for in vitro immunological studies. To profile the immune recognition and interaction from exposure to PVP–AuNPs (1 and 10 μg mL−1), we applied an extensive nano-scale approach, including particle physicochemical characterisation involving immunology, cellular biology, and metabolomics. The interaction between PVP–AuNPs and soluble proteins of the sea urchin physiological coelomic fluid (blood equivalent) results in the formation of a protein “corona” surrounding the NPs from three major proteins that influence the hydrodynamic size and colloidal stability of the particle. At the lower concentration of PVP–AuNPs, the P. lividus phagocytes show a broad metabolic plasticity based on the biosynthesis of metabolites mediating inflammation and phagocytosis. At the higher concentration of PVP–AuNPs, phagocytes activate an immunological response involving Toll-like receptor 4 (TLR4) signalling pathway at 24 hours of exposure. These results emphasise that exposure to PVP–AuNPs drives inflammatory signalling by the phagocytes and the resolution at both the low and high concentrations of the PVP–AuNPs and provides more details regarding the immunogenicity of these NPs. © 2020 Elsevier B.V.


  • Graphene active sensor arrays for long-term and wireless mapping of wide frequency band epicortical brain activity

    Garcia-Cortadella R., Schwesig G., Jeschke C., Illa X., Gray A.L., Savage S., Stamatidou E., Schiessl I., Masvidal-Codina E., Kostarelos K., Guimerà-Brunet A., Sirota A., Garrido J.A. Nature Communications; 12 (1, 211) 2021. 10.1038/s41467-020-20546-w. IF: 12.121

    Nanomedicine | Advanced Electronic Materials and Devices

    Graphene active sensors have demonstrated promising capabilities for the detection of electrophysiological signals in the brain. Their functional properties, together with their flexibility as well as their expected stability and biocompatibility have raised them as a promising building block for large-scale sensing neural interfaces. However, in order to provide reliable tools for neuroscience and biomedical engineering applications, the maturity of this technology must be thoroughly studied. Here, we evaluate the performance of 64-channel graphene sensor arrays in terms of homogeneity, sensitivity and stability using a wireless, quasi-commercial headstage and demonstrate the biocompatibility of epicortical graphene chronic implants. Furthermore, to illustrate the potential of the technology to detect cortical signals from infra-slow to high-gamma frequency bands, we perform proof-of-concept long-term wireless recording in a freely behaving rodent. Our work demonstrates the maturity of the graphene-based technology, which represents a promising candidate for chronic, wide frequency band neural sensing interfaces. © 2021, The Author(s).


  • Graphene quantum dots: From efficient preparation to safe renal excretion

    Hadad C., González-Domínguez J.M., Armelloni S., Mattinzoli D., Ikehata M., Istif A., Ostric A., Cellesi F., Alfieri C.M., Messa P., Ballesteros B., Da Ros T. Nano Research; 14 (3): 674 - 683. 2021. 10.1007/s12274-020-3096-y. IF: 8.183

    Electron Microscopy Unit

    Carbon nanomaterials offer excellent prospects as therapeutic agents, and among them, graphene quantum dots (GQDs) have gained considerable interest thanks to their aqueous solubility and intrinsic fluorescence, which enable their possible use in theranostic approaches, if their biocompatibility and favorable pharmacokinetic are confirmed. We prepared ultra-small GQDs using an alternative, reproducible, top-down synthesis starting from graphene oxide with a nearly 100% conversion. The materials were tested to assess their safety, demonstrating good biocompatibility and ability in passing the ultrafiltration barrier using an in vitro model. This leads to renal excretion without affecting the kidneys. Moreover, we studied the GQDs in vivo biodistribution confirming their efficient renal clearance, and we demonstrated that the internalization mechanism into podocytes is caveolae-mediated. Therefore, considering the reported characteristics, it appears possible to vehiculate compounds to kidneys by means of GQDs, overcoming problems related to lysosomal degradation. [Figure not available: see fulltext.]. © 2020, The Author(s).


  • Grating-Graphene Metamaterial as a Platform for Terahertz Nonlinear Photonics

    Deinert J.-C., Alcaraz Iranzo D., Pérez R., Jia X., Hafez H.A., Ilyakov I., Awari N., Chen M., Bawatna M., Ponomaryov A.N., Germanskiy S., Bonn M., Koppens F.H.L., Turchinovich D., Gensch M., Kovalev S., Tielrooij K.-J. ACS Nano; 2021. 10.1021/acsnano.0c08106. IF: 14.588

    Ultrafast Dynamics in Nanoscale Systems

    Nonlinear optics is an increasingly important field for scientific and technological applications, owing to its relevance and potential for optical and optoelectronic technologies. Currently, there is an active search for suitable nonlinear material systems with efficient conversion and a small material footprint. Ideally, the material system should allow for chip integration and room-temperature operation. Two-dimensional materials are highly interesting in this regard. Particularly promising is graphene, which has demonstrated an exceptionally large nonlinearity in the terahertz regime. Yet, the light-matter interaction length in two-dimensional materials is inherently minimal, thus limiting the overall nonlinear optical conversion efficiency. Here, we overcome this challenge using a metamaterial platform that combines graphene with a photonic grating structure providing field enhancement. We measure terahertz third-harmonic generation in this metamaterial and obtain an effective third-order nonlinear susceptibility with a magnitude as large as 3 × 10-8 m2/V2, or 21 esu, for a fundamental frequency of 0.7 THz. This nonlinearity is 50 times larger than what we obtain for graphene without grating. Such an enhancement corresponds to a third-harmonic signal with an intensity that is 3 orders of magnitude larger due to the grating. Moreover, we demonstrate a field conversion efficiency for the third harmonic of up to μ1% using a moderate field strength of μ30 kV/cm. Finally, we show that harmonics beyond the third are enhanced even more strongly, allowing us to observe signatures of up to the ninth harmonic. Grating-graphene metamaterials thus constitute an outstanding platform for commercially viable, CMOS-compatible, room-temperature, chip-integrated, THz nonlinear conversion applications. © 2020 American Chemical Society.


  • Heat transport control and thermal characterization of low-dimensional materials: A review

    El Sachat A., Alzina F., Sotomayor Torres C.M., Chavez-Angel E. Nanomaterials; 11 (1, 175): 1 - 32. 2021. 10.3390/nano11010175. IF: 4.324

    Phononic and Photonic Nanostructures

    Heat dissipation and thermal management are central challenges in various areas of science and technology and are critical issues for the majority of nanoelectronic devices. In this review, we focus on experimental advances in thermal characterization and phonon engineering that have drastically increased the understanding of heat transport and demonstrated efficient ways to control heat propagation in nanomaterials. We summarize the latest device-relevant methodologies of phonon engineering in semiconductor nanostructures and 2D materials, including graphene and transition metal dichalcogenides. Then, we review recent advances in thermal characterization techniques, and discuss their main challenges and limitations. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks: The case of squaramide

    Broto-Ribas A., Vignatti C., Jimenez-Almarza A., Luis-Barrera J., Dolatkhah Z., Gándara F., Imaz I., Mas-Ballesté R., Alemán J., Maspoch D. Nano Research; 14 (2): 458 - 465. 2021. 10.1007/s12274-020-2779-8. IF: 8.183

    Supramolecular NanoChemistry and Materials

    A well-established strategy to synthesize heterogeneous, metal-organic framework (MOF) catalysts that exhibit nanoconfinement effects, and specific pores with highly-localized catalytic sites, is to use organic linkers containing organocatalytic centers. Here, we report that by combining this linker approach with reticular chemistry, and exploiting three-dimensioanl (3D) MOF-structural data from the Cambridge Structural Database, we have designed four heterogeneous MOF-based catalysts for standard organic transformations. These programmable MOFs are isoreticular versions of pcu IRMOF-16, fcu UiO-68 and pillared-pcu SNU-8X, the three most common topologies of MOFs built from the organic linker p,p’-terphenyldicarboxylic acid (tpdc). To synthesize the four squaramide-based MOFs, we designed and synthesized a linker, 4,4’-((3,4‐dioxocyclobut‐1‐ene‐1,2‐diyl)bis(azanedyil))dibenzoic acid (Sq_tpdc), which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers. Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena. Therefore, the four MOFs share the same organocatalytic squaramide moiety, but confine it within distinct pore environments. We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations: a Friedel-Crafts alkylation and an epoxide ring-opening. Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences. [Figure not available: see fulltext.]. © 2020, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.


  • 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: 9.038

    Nanobioelectronics and Biosensors

    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.


  • In situ XPS analysis of the electronic structure of silicon and titanium thin films exposed to low-pressure inductively-coupled RF plasma

    Fraxedas J., Schütte M., Sauthier G., Tallarida M., Ferrer S., Carlino V., Pellegrin E. Applied Surface Science; 542 (148684) 2021. 10.1016/j.apsusc.2020.148684. IF: 6.182

    Force Probe Microscopy and Surface Nanoengineering

    Carbon contamination of synchrotron and free-electron lasers beamline optics continues to be a major nuisance due to the interaction of the intense photon beams with the surfaces of the optical elements in the presence of residual gases even in ultrahigh vacuum (UHV) conditions. Among the available in situ cleaning strategies, low-pressure radio frequency (RF) plasma treatment has emerged as a useful and relatively simple approach to remove such carbon contamination. However, the irreversible damage that the plasma may induce in such critical surfaces has to be carefully characterized before its general application. In this study, we focus on reducing the amount of carbon from UHV chamber inside surfaces via silicon and titanium coatings using a low-pressure inductively-coupled downstream plasma source and we characterize the surface alterations by in situ X-ray photoemission spectroscopy (XPS). The in situ mirror cleaning is simulated by means of silicon wafers. We observe upward band bending, which translates into lower binding energies of the photoemission lines, that we attribute to the generation of vacancies and trapped charges in the oxide layers. © 2020 Elsevier B.V.


  • Injection locking in an optomechanical coherent phonon source

    Arregui G., Colombano M.F., Maire J., Pitanti A., Capuj N.E., Griol A., Martínez A., Sotomayor-Torres C.M., Navarro-Urrios D. Nanophotonics; 2021. 10.1515/nanoph-2020-0592. IF: 7.491

    Phononic and Photonic Nanostructures

    Spontaneous locking of the phase of a coherent phonon source to an external reference is demonstrated in a deeply sideband-unresolved optomechanical system. The high-amplitude mechanical oscillations are driven by the anharmonic modulation of the radiation pressure force that result from an absorption-mediated free-carrier/temperature limit cycle, i.e., self-pulsing. Synchronization is observed when the pump laser driving the mechanical oscillator to a self-sustained state is modulated by a radiofrequency tone. We employ a pump-probe phonon detection scheme based on an independent optical cavity to observe only the mechanical oscillator dynamics. The lock range of the oscillation frequency, i.e., the Arnold tongue, is experimentally determined over a range of external reference strengths, evidencing the possibility to tune the oscillator frequency for a range up to 350 kHz. The stability of the coherent phonon source is evaluated via its phase noise, with a maximum achieved suppression of 44 dBc/Hz at 1 kHz offset for a 100 MHz mechanical resonator. Introducing a weak modulation in the excitation laser reveals as a further knob to trigger, control and stabilize the dynamical solutions of self-pulsing based optomechanical oscillators, thus enhancing their potential as acoustic wave sources in a single-layer silicon platform. © 2021 Guillermo Arregui et al., published by De Gruyter, Berlin/Boston 2021.


  • 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; 2021. 10.1002/adfm.202010388. IF: 16.836

    Nanobioelectronics and Biosensors

    “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


  • 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: 3.998

    Nanobioelectronics and Biosensors

    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).


  • Interaction between macrophages and nanoparticles: In vitro 3d cultures for the realistic assessment of inflammatory activation and modulation of innate memory

    Swartzwelter B.J., Verde A., Rehak L., Madej M., Puntes V.F., De Luca A.C., Boraschi D., Italiani P. Nanomaterials; 11 (1, 207): 1 - 13. 2021. 10.3390/nano11010207. IF: 4.324

    Inorganic Nanoparticles

    Understanding the modes of interaction between human monocytes/macrophages and engineered nanoparticles is the basis for assessing particle safety, in terms of activation of innate/inflammatory reactions, and their possible exploitation for medical applications. In vitro assessment of nanoparticle-macrophage interaction allows for examining the response of primary human cells, but the conventional 2D cultures do not reproduce the three-dimensional spacing of a tissue and the interaction of macrophages with the extracellular tissue matrix, conditions that shape macrophage recognition capacity and reactivity. Here, we have compared traditional 2D cultures with cultures on a 3D collagen matrix for evaluating the capacity gold nanoparticles to induce monocyte activation and subsequent innate memory in human blood monocytes in comparison to bacterial LPS. Results show that monocytes react to stimuli almost in the same way in 2D and 3D cultures in terms of production of TNFα and IL-6, but that notable differences are found when IL-8 and IL-1Ra are examined, in particular in the recall/memory response of primed cells to a second stimulation, with the 3D cultures showing cell activation and memory effects of nanoparticles better. In addition, the response variations in monocytes/macrophages from different donors point towards a personalized assessment of the nanoparticle effects on macrophage activation. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Introducing visible-light sensitivity into photocatalytic CeO2nanoparticles by hybrid particle preparation exploiting plasmonic properties of gold: Enhanced photoelectrocatalysis exemplified for hydrogen peroxide sensing

    Zhao S., Riedel M., Patarroyo J., Bastus N., Puntes V., Yue Z., Lisdat F., Parak W.J. Nanoscale; 13 (2): 980 - 990. 2021. 10.1039/d0nr06356h. IF: 6.895

    Inorganic Nanoparticles

    In this report we combine the catalytic properties of CeO2 nanoparticles with their transduction ability for photoelectrochemical sensing. This study highlights the usage of CeO2 providing catalytic activity towards H2O2, but only with a limited excitation range in the UV for the construction of a sensing system. In order to improve the photoelectrocatalysis of CeO2 nanoparticles by extending their excitation to visible light, Au/CeO2 core/shell hybrid nanoparticles have been synthesized. The hybrid nanoparticles are fixed on electrodes, allowing for the generation of photocurrents, the direction of which can be controlled by the electrode potential (without bias). The application of the hybrid nanoparticles results in an enhanced photocurrent amplitude under white light illumination as compared to the pure CeO2 nanoparticles. Wavelength-dependent measurements confirm the participation of the Au core in the signal transduction. This can be explained by improved charge carrier generation within the hybrid particles. Thus, by using a plasmonic element the photoelectochemical response of a catalytic nanoparticle (i.e. CeO2) has been spectrally extended. The effect can be exploited for sensorial hydrogen peroxide detection. Here higher photocatalytic current responses have been found for the hybrid particles fixed to gold electrodes although the catalytic reduction has been comparable for both types of nanoparticles. Thus, it can be demonstrated that Au/CeO2 core-shell nanoparticles allow the utilization of visible light for photoelectrochemical hydrogen peroxide (H2O2) detection with improved sensitivity under white light illumination or application of such particles with only visible light excitation, which is not possible for pure CeO2. With help of the layer-by-layer (LbL) technique for nanoparticle immobilization, the electrode response can be adjusted and with a 5 layers electrode a low detection limit of about 3 μM H2O2 with a linear detection range up to 2000 μM is obtained. This journal is © The Royal Society of Chemistry.


  • Layered Nanocomposite 2D-TiO2 with Cu2O Nanoparticles as an Efficient Photocatalyst for 4-Chlorophenol Degradation and Hydrogen Evolution

    Alegría M., Aliaga J., Ballesteros L., Sotomayor-Torres C., González G., Benavente E. Topics in Catalysis; 64 (1-2): 167 - 180. 2021. 10.1007/s11244-020-01360-6. IF: 2.406

    Phononic and Photonic Nanostructures

    New composites formed by layered hybrid TiO2(stearic acid) (LHTiO2) and, Cu2O nanoparticles were studied as photocatalysts that extend the response range to light visible for the evolution of hydrogen and the degradation of 4-chlorophenol. The results revealed that LHTiO2/Cu2O exhibited a clearly improved photocatalytic degradation, about 5.6 times faster than pristine TiO2, and hydrogen evolution of about 2.7 times higher than the TiO2 anatase. The enhanced photocatalytic activity can be assigned to the properties of the two-dimensional morphology, in sheets-like arrangement of LHTiO2, benefitting from the high exposure of surface, with more active sites available to improve matching with the surfaces of the Cu2O nanocrystals and significant reduction of migration distances of photogenerated carriers. In the photocatalytic degradation, a mechanism Z-scheme is supported, and in the photocatalytic evolution of hydrogen a mechanism type II band alignment is indicated. Photocatalytic reuse tests showed that stability and catalytic activity of LHTiO2/Cu2O were maintained for three cycles. Photoelectrochemical evaluation were performed through measurements of the photocurrent response and electrochemical impedance. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.


  • Linear scaling quantum transport methodologies

    Fan Z., Garcia J.H., Cummings A.W., Barrios-Vargas J.E., Panhans M., Harju A., Ortmann F., Roche S. Physics Reports; 2021. 10.1016/j.physrep.2020.12.001. IF: 25.809

    Theoretical and Computational Nanoscience

    In recent years, predictive computational modeling has become a cornerstone for the study of fundamental electronic, optical, and thermal properties in complex forms of condensed matter, including Dirac and topological materials. The simulation of quantum transport in realistic models calls for the development of linear scaling, or order-N, numerical methods, which then become enabling tools for guiding experimental research and for supporting the interpretation of measurements. In this review, we describe and compare different order-N computational methods that have been developed during the past twenty years, and which have been used extensively to explore quantum transport phenomena in disordered media. We place particular focus on the zero-frequency electrical conductivities derived within the Kubo–Greenwood​ and Kubo–Streda formalisms, and illustrate the capabilities of these methods to tackle the quasi-ballistic, diffusive, and localization regimes of quantum transport in the noninteracting limit. The fundamental issue of computational cost versus accuracy of various proposed numerical schemes is addressed in depth. We then illustrate the usefulness of these methods with various examples of transport in disordered materials, such as polycrystalline and defected graphene models, 3D metals and Dirac semimetals, carbon nanotubes, and organic semiconductors. Finally, we extend the review to the study of spin dynamics and topological transport, for which efficient approaches for calculating charge, spin, and valley Hall conductivities are described. © 2020 The Author(s)


  • Metallic Diluted Dimerization in VO2 Tweeds

    Sandiumenge F., Rodríguez L., Pruneda M., Magén C., Santiso J., Catalan G. Advanced Materials; 2021. 10.1002/adma.202004374. IF: 27.398

    Theory and Simulation | Oxide Nanophysics | Nanomaterials Growth Unit

    The observation of electronic phase separation textures in vanadium dioxide, a prototypical electron-correlated oxide, has recently added new perspectives on the long standing debate about its metal–insulator transition and its applications. Yet, the lack of atomically resolved information on phases accompanying such complex patterns still hinders a comprehensive understanding of the transition and its implementation in practical devices. In this work, atomic resolution imaging and spectroscopy unveils the existence of ferroelastic tweed structures on ≈5 nm length scales, well below the resolution limit of currently used spectroscopic imaging techniques. Moreover, density functional theory calculations show that this pretransitional fine-scale tweed, which on average looks and behaves like the standard metallic rutile phase, is in fact weaved by semi-dimerized chains of vanadium in a new monoclinic phase that represents a structural bridge to the monoclinic insulating ground state. These observations provide a multiscale perspective for the interpretation of existing data, whereby phase coexistence and structural intermixing can occur all the way down to the atomic scale. © 2021 Wiley-VCH GmbH


  • Microfluidic In Vitro Platform for (Nano)Safety and (Nano)Drug Efficiency Screening

    Kohl Y., Biehl M., Spring S., Hesler M., Ogourtsov V., Todorovic M., Owen J., Elje E., Kopecka K., Moriones O.H., Bastús N.G., Simon P., Dubaj T., Rundén-Pran E., Puntes V., William N., von Briesen H., Wagner S., Kapur N., Mariussen E., Nelson A., Gabelova A., Dusinska M., Velten T., Knoll T. Small; 2021. 10.1002/smll.202006012. IF: 11.459

    Inorganic Nanoparticles

    Microfluidic technology is a valuable tool for realizing more in vitro models capturing cellular and organ level responses for rapid and animal-free risk assessment of new chemicals and drugs. Microfluidic cell-based devices allow high-throughput screening and flexible automation while lowering costs and reagent consumption due to their miniaturization. There is a growing need for faster and animal-free approaches for drug development and safety assessment of chemicals (Registration, Evaluation, Authorisation and Restriction of Chemical Substances, REACH). The work presented describes a microfluidic platform for in vivo-like in vitro cell cultivation. It is equipped with a wafer-based silicon chip including integrated electrodes and a microcavity. A proof-of-concept using different relevant cell models shows its suitability for label-free assessment of cytotoxic effects. A miniaturized microscope within each module monitors cell morphology and proliferation. Electrodes integrated in the microfluidic channels allow the noninvasive monitoring of barrier integrity followed by a label-free assessment of cytotoxic effects. Each microfluidic cell cultivation module can be operated individually or be interconnected in a flexible way. The interconnection of the different modules aims at simulation of the whole-body exposure and response and can contribute to the replacement of animal testing in risk assessment studies in compliance with the 3Rs to replace, reduce, and refine animal experiments. © 2021 The Authors. Small published by Wiley-VCH GmbH


  • Nanophotonic biosensors for point-of-care COVID-19 diagnostics and coronavirus surveillance

    Ruiz-Vega G., Soler M., Lechuga L.M. JPhys Photonics; 3 (1, 011002) 2021. 10.1088/2515-7647/abd4ee. IF: 0.000

    NanoBiosensors and Bioanalytical Applications

    The COVID-19 pandemic has revealed the need of novel diagnostic technologies for rapid and accurate virus detection. In the European CONVAT project, a point-of-care nanophotonic biosensor is being developed for the direct, fast and specific identification of severe acute respiratory syndrome coronavirus 2 from both human patient samples and animal reservoirs. The technology will provide a quantitative detection of the viral load and it can be implemented in decentralized settings to improve the early diagnosis and clinical management of patients as well as coronavirus environmental monitoring to prevent future outbreaks. © 2021 The Author(s). Published by IOP Publishing Ltd


  • Nanotools for Sepsis Diagnosis and Treatment

    Papafilippou L., Claxton A., Dark P., Kostarelos K., Hadjidemetriou M. Advanced Healthcare Materials; 10 (1, 2001378) 2021. 10.1002/adhm.202001378. IF: 7.367

    Nanomedicine

    Sepsis is one of the leading causes of death worldwide with high mortality rates and a pathological complexity hindering early and accurate diagnosis. Today, laboratory culture tests are the epitome of pathogen recognition in sepsis. However, their consistency remains an issue of controversy with false negative results often observed. Clinically used blood markers, C reactive protein (CRP) and procalcitonin (PCT) are indicators of an acute-phase response and thus lack specificity, offering limited diagnostic efficacy. In addition to poor diagnosis, inefficient drug delivery and the increasing prevalence of antibiotic-resistant microorganisms constitute significant barriers in antibiotic stewardship and impede effective therapy. These challenges have prompted the exploration for alternative strategies that pursue accurate diagnosis and effective treatment. Nanomaterials are examined for both diagnostic and therapeutic purposes in sepsis. The nanoparticle (NP)-enabled capture of sepsis causative agents and/or sepsis biomarkers in biofluids can revolutionize sepsis diagnosis. From the therapeutic point of view, currently existing nanoscale drug delivery systems have proven to be excellent allies in targeted therapy, while many other nanotherapeutic applications are envisioned. Herein, the most relevant applications of nanomedicine for the diagnosis, prognosis, and treatment of sepsis is reviewed, providing a critical assessment of their potentiality for clinical translation. © 2020 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH


  • Nickel Iron Diselenide for Highly Efficient and Selective Electrocatalytic Conversion of Methanol to Formate

    Li J., Xing C., Zhang Y., Zhang T., Spadaro M.C., Wu Q., Yi Y., He S., Llorca J., Arbiol J., Cabot A., Cui C. Small; 17 (6, 2006623) 2021. 10.1002/smll.202006623. IF: 11.459

    Advanced Electron Nanoscopy

    The electro-oxidation of methanol to formate is an interesting example of the potential use of renewable energies to add value to a biosourced chemical commodity. Additionally, methanol electro-oxidation can replace the sluggish oxygen evolution reaction when coupled to hydrogen evolution or to the electroreduction of other biomass-derived intermediates. But the cost-effective realization of these reaction schemes requires the development of efficient and low-cost electrocatalysts. Here, a noble metal-free catalyst, Ni1−xFexSe2 nanorods, with a high potential for an efficient and selective methanol conversion to formate is demonstrated. At its optimum composition, Ni0.75Fe0.25Se2, this diselenide is able to produce 0.47 mmol cm−2 h−1 of formate at 50 mA cm−2 with a Faradaic conversion efficiency of 99%. Additionally, this noble-metal-free catalyst is able to continuously work for over 50 000 s with a minimal loss of efficiency, delivering initial current densities above 50 mA cm−2 and 2.2 A mg−1 in a 1.0 m KOH electrolyte with 1.0 m methanol at 1.5 V versus reversible hydrogen electrode. This work demonstrates the highly efficient and selective methanol-to-formate conversion on Ni-based noble-metal-free catalysts, and more importantly it shows a very promising example to exploit the electrocatalytic conversion of biomass-derived chemicals. © 2021 Wiley-VCH GmbH


  • Non-linear nanoscale piezoresponse of single ZnO nanowires affected by piezotronic effect

    Lozano H., Catalán G., Esteve J., Domingo N., Murillo G. Nanotechnology; 32 (2, 025202) 2021. 10.1088/1361-6528/abb972. IF: 3.551

    Oxide Nanophysics

    Zinc oxide (ZnO) nanowires (NWs) as semiconductor piezoelectric nanostructures have emerged as material of interest for applications in energy harvesting, photonics, sensing, biomedical science, actuators or spintronics. The expression for the piezoelectric properties in semiconductor materials is concealed by the screening effect of the available carriers and the piezotronic effect, leading to complex nanoscale piezoresponse signals. Here, we have developed a metal-semiconductor-metal model to simulate the piezoresponse of single ZnO NWs, demonstrating that the apparent non-linearity in the piezoelectric coefficient arises from the asymmetry created by the forward and reversed biased Schottky barriers at the semiconductor-metal junctions. By directly measuring the experimental I-V characteristics of ZnO NWs with conductive atomic force microscope together with the piezoelectric vertical coefficient by piezoresponse force microscopy, and comparing them with the numerical calculations for our model, effective piezoelectric coefficients in the range d 33eff ∼ 8.6 pm V-1-12.3 pm V-1 have been extracted for ZnO NWs. We have further demonstrated via simulations the dependence between the effective piezoelectric coefficient d 33eff and the geometry and physical dimensions of the NW (radius to length ratio), revealing that the higher d 33eff is obtained for thin and long NWs due to the tensor nature proportionality between electric fields and deformation in NW geometries. Moreover, the non-linearity of the piezoresponse also leads to multiharmonic electromechanical response observed at the second and higher harmonics that indeed is not restricted to piezoelectric semiconductor materials but can be generalized to any type of asymmetric voltage drops on a piezoelectric structure as well as leaky wide band-gap semiconductor ferroelectrics. © 2020 IOP Publishing Ltd.


  • Optimisation of NiO electrodeposition on 3D graphene electrode for electrochemical energy storage using response surface methodology

    Agudosi E.S., Abdullah E.C., Numan A., Khalid M., Mubarak N.M., Benages-Vilau R., Gómez-Romero P., Aid S.R., Omar N. Journal of Electroanalytical Chemistry; 882 (114992) 2021. 10.1016/j.jelechem.2021.114992. IF: 3.807

    Novel Energy-Oriented Materials

    In this study, NiO was electrodeposited on a 3D graphene electrode to produce a nanocomposite with enhanced electrochemical properties. The electrodeposition process parameters such as electrolyte concentration, deposition time, and deposition potential were statistically optimised using response surface methodology. The statistical analysis showed that the optimal electrodeposition conditions to be 0.3 M, 10 min, and -1.2 V for electrolyte concentration, deposition time, and deposition potential, respectively. Furthermore, the predicted model and experimental results for the specific capacity of G-NiO were determined to be 240.91 C/g and 240.58 C/g at 3 mV/s. The results show that the electrochemical deposition technique can be employed as a fast and reliable synthesis route to develop graphene-based metal oxide nanocomposites. The structural and morphological properties were determined by XRD and FESEM studies. The electrochemical measurements revealed the excellent electrochemical performance of 3D graphene NiO composite (G-NiO) for energy storage applications. © 2021 Elsevier B.V.


  • Paper-Based Electrophoretic Bioassay: Biosensing in Whole Blood Operating via Smartphone

    Sena-Torralba A., Alvarez-Diduk R., Parolo C., Torné-Morató H., Müller A., Merkoçi A. Analytical Chemistry; 2021. 10.1021/acs.analchem.0c04330. IF: 6.785

    Nanobioelectronics and Biosensors

    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 paper-based 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. © 2020 American Chemical Society. All rights reserved.


  • Probing the meta-stability of oxide core/shell nanoparticle systems at atomic resolution

    Roldan M.A., Mayence A., López-Ortega A., Ishikawa R., Salafranca J., Estrader M., Salazar-Alvarez G., Dolors Baró M., Nogués J., Pennycook S.J., Varela M. Chemical Engineering Journal; 405 (126820) 2021. 10.1016/j.cej.2020.126820. IF: 10.652

    Magnetic Nanostructures

    Hybrid nanoparticles allow exploiting the interplay of confinement, proximity between different materials and interfacial effects. However, to harness their properties an in-depth understanding of their (meta)stability and interfacial characteristics is crucial. This is especially the case of nanosystems based on functional oxides working under reducing conditions, which may severely impact their properties. In this work, the in-situ electron-induced selective reduction of Mn3O4 to MnO is studied in magnetic Fe3O4/Mn3O4 and Mn3O4/Fe3O4 core/shell nanoparticles by means of high-resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Such in-situ transformation allows mimicking the actual processes in operando environments. A multi-stage image analysis using geometric phase analysis combined with particle image velocity enables direct monitoring of the relationship between structure, chemical composition and strain relaxation during the Mn3O4 reduction. In the case of Fe3O4/Mn3O4 core/shell the transformation occurs smoothly without the formation of defects. However, for the inverse Mn3O4/Fe3O4 core/shell configuration the electron beam-induced transformation occurs in different stages that include redox reactions and void formation followed by strain field relaxation via formation of defects. This study highlights the relevance of understanding the local dynamics responsible for changes in the particle composition in order to control stability and, ultimately, macroscopic functionality. © 2020 Elsevier B.V.


  • Pyroelectric thin films - Past, present, and future

    Velarde G., Pandya S., Karthik J., Pesquera D., Martin L.W. APL Materials; 9 (1, 010702) 2021. 10.1063/5.0035735. IF: 3.819

    Oxide Nanophysics

    Pyroelectrics are a material class that undergoes a change in polarization as the temperature of the system is varied. This effect can be utilized for applications ranging from thermal imaging and sensing to waste-heat energy conversion to thermally driven electron emission. Here, we review recent advances in the study and utilization of thin-film pyroelectrics. Leveraging advances in modeling, synthesis, and characterization has provided a pathway forward in one of the more poorly developed subfields of ferroelectricity. We introduce the complex physical phenomena of pyroelectricity, briefly explore the history of work in this space, and highlight not only new advances in the direct measurement of such effects but also how our ability to control thin-film materials is changing our understanding of this response. Finally, we discuss recent advances in thin-film pyroelectric devices and introduce a number of potentially new directions the field may follow in the coming years. © 2021 Author(s).


  • Quantifying the Robustness of Topological Slow Light

    Arregui G., Gomis-Bresco J., Sotomayor-Torres C.M., Garcia P.D. Physical Review Letters; 126 (2, 027403) 2021. 10.1103/PhysRevLett.126.027403. IF: 8.385

    Phononic and Photonic Nanostructures

    The backscattering mean free path ζ, the average ballistic propagation length along a waveguide, quantifies the resistance of slow light against unwanted imperfections in the critical dimensions of the nanostructure. This figure of merit determines the crossover between acceptable slow-light transmission affected by minimal scattering losses and a strong backscattering-induced destructive interference when the waveguide length L exceeds ζ. Here, we calculate the backscattering mean free path for a topological photonic waveguide for a specific and determined amount of disorder and, equally relevant, for a fixed value of the group index ng which is the slowdown factor of the group velocity with respect to the speed of light in vacuum. These two figures of merit, ζand ng, should be taken into account when quantifying the robustness of topological and conventional (nontopological) slow-light transport at the nanoscale. Otherwise, any claim on a better performance of topological guided light over a conventional one is not justified. © 2021 American Physical Society.


  • Real-time monitoring of fenitrothion in water samples using a silicon nanophotonic biosensor

    Ramirez-Priego P., Estévez M.-C., Díaz-Luisravelo H.J., Manclús J.J., Montoya Á., Lechuga L.M. Analytica Chimica Acta; 1152 (338276) 2021. 10.1016/j.aca.2021.338276. IF: 5.977

    NanoBiosensors and Bioanalytical Applications

    Due to the large quantities of pesticides extensively used and their impact on the environment and human health, a prompt and reliable sensing technique could constitute an excellent tool for in-situ monitoring. With this aim, we have applied a highly sensitive photonic biosensor based on a bimodal waveguide interferometer (BiMW) for the rapid, label-free, and specific quantification of fenitrothion (FN) directly in tap water samples. After an optimization protocol, the biosensor achieved a limit of detection (LOD) of 0.29 ng mL−1 (1.05 nM) and a half-maximal inhibitory concentration (IC50) of 1.71 ng mL−1 (6.09 nM) using a competitive immunoassay and employing diluted tap water. Moreover, the biosensor was successfully employed to determine FN concentration in blind tap water samples obtaining excellent recovery percentages with a time-to-result of only 20 min without any sample pre-treatment. The features of the biosensor suggest its potential application for real time, fast and sensitive screening of FN in water samples as an analytical tool for the monitoring of the water quality. © 2021 Elsevier B.V.


  • Room temperature synthesis and characterization of novel lead-free double perovskite nanocrystals with a stable and broadband emission

    Tang Y., Gomez L., Van Der Laan M., Timmerman D., Sebastian V., Huang C.-C., Gregorkiewicz T., Schall P. Journal of Materials Chemistry C; 9 (1): 158 - 163. 2021. 10.1039/d0tc04394j. IF: 7.059

    Supramolecular NanoChemistry and Materials | NanoBiosensors and Bioanalytical Applications

    Low-dimensional and lead-free halide perovskites are of great interest for their wide application potential for optoelectronic applications. We report on the successful synthesis of novel lead-free colloidal Cs3BiBr6 nanocrystals (NCs) with an ultra-small size of ∼1.5-3 nm by a room temperature antisolvent process. From crystallographic characterization we show that it is critical to precisely control the ratio of precursors to obtain the pure 3-1-6 phase. The synthesis process is facile and repeatable and results in Cs3BiBr6 NCs that display stable blue emission around 438 nm with a relatively broad linewidth of 92.1 nm. Low-temperature photoluminescence (PL) measurements displayed a red-shift of bandgap with decreasing temperature, which might be attributed to the thermal expansion of the lattice. In addition, the NCs demonstrate high stability at ambient conditions. This journal is © The Royal Society of Chemistry.


  • Sheet-on-sheet like calcium ferrite and graphene nanoplatelets nanocomposite: A multifunctional nanocomposite for high-performance supercapacitor and visible light driven photocatalysis

    Israr M., Iqbal J., Arshad A., Gómez-Romero P. Journal of Solid State Chemistry; 293 (121646) 2021. 10.1016/j.jssc.2020.121646. IF: 2.726

    Novel Energy-Oriented Materials

    Calcium ferrite-graphene nanoplatelets nanocomposites with sheet-on-sheet like morphology are fabricated and investigated for their physicochemical characteristics, electrochemical energy storage capacity and photocatalysis. Interestingly, the (CF)1-x (GNPs)x nanocomposite-based electrode has shown maximum specific capacitance up to 422 ​Fg-1 at 0.25 Ag-1 with excellent cycling stability, 2.6 times higher than that of neat CF nanosheets. Furthermore, the synergistic contribution from photocatalytic and photo-Fenton reactions enables (CF)1-x (GNPs)x nanocomposites to offer superior photocatalytic activity (99.4% dye removal in 90 ​min). The inclusion of GNPs significantly enhances the charge carriers separation and transportation. The excellent electrochemical efficiency of (CF)1-x (GNPs)x could be attributed to the 2D interfacial interactions that provide a better charge transport at electrode/electrolyte interface. These interactions are also responsible for creating effective charge transport pathways and efficient e−/h+ separation leading to rapid dye-degradation, which make the material potential for remediation of water pollution and energy storage systems. © 2020 Elsevier Inc.


  • Solvent-tuned ultrasonic synthesis of 2D coordination polymer nanostructures and flakes

    Pepió B., Contreras-Pereda N., Suárez-García S., Hayati P., Benmansour S., Retailleau P., Morsali A., Ruiz-Molina D. Ultrasonics Sonochemistry; 72 (105425) 2021. 10.1016/j.ultsonch.2020.105425. IF: 6.513

    Nanostructured Functional Materials

    Herein, a new 2-dimensional coordination polymer based on copper (II), {Cu2(L)(DMF)2}n, where L stands for 1,2,4,5-benzenetetracarboxylate (complex 1) is synthesized. Interestingly, we demonstrate that both solvent and sonication are relevant in the top-down fabrication of nanostructures. Water molecules are intercalated in suspended crystals of complex 1 modifying not only the coordination sphere of Cu(II) ions but also the final chemical formula and crystalline structure obtaining {[Cu(L)(H2O)3]·H2O}n (complex 2). On the other hand, ultrasound is required to induce the nanostructuration. Remarkably, different morphologies are obtained using different solvents and interconversion from one morphology to another seems to occur upon solvent exchange. Both complexes 1 and 2, as well as the corresponding nanostructures, have been fully characterized by different means such as infrared spectroscopy, x-ray diffraction and microscopy. © 2020 The Authors


  • Stress-mediated solution deposition method to stabilize ferroelectric BiFe1-xCrxO3 perovskite thin films with narrow bandgaps

    Jiménez R., Ricote J., Bretos I., Jiménez Riobóo R.J., Mompean F., Ruiz A., Xie H., Lira-Cantú M., Calzada M.L. Journal of the European Ceramic Society; 2021. 10.1016/j.jeurceramsoc.2020.12.042. IF: 4.495

    Nanostructured Materials for Photovoltaic Energy

    Ferroelectric oxides with low bandgaps are mainly based on the BiFeO3 perovskite upon the partial substitution of iron with different cations. However, the structural stability of many of these perovskites is only possible by their processing at high pressures (HP, >1GPa) and high temperatures (HT, >700ºC). Preparation methods under these severe conditions are accessible to powders and bulk ceramics. However, transferring these conditions to the fabrication of thin films is a challenge, thus limiting their use in applications. Here, a chemical solution deposition method is devised, which overcomes many of these restrictions. It is based on the application of an external compressive-stress to the film sample during the thermal treatment required for the film crystallization, promoting the formation and stabilization of these HP perovskites. We demonstrate the concept on BiFe1-xCrxO3 (BFCO) thin films deposited on SrTiO3 (STO) substrates and with large chromium contents. The resulting BFCO perovskite films show narrow bandgaps (Eg∼2.57 eV) and an excellent ferroelectric response (remnant polarization, PR∼ 40 μC cm−2). The polarized thin films under illumination present a large out-put power of ∼6.4 μW cm−2, demonstrating their potential for using in self-powered multifunctional devices. This stress-mediated solution deposition method can be extended to other perovskite films which are unviable under conventional deposition methods. © 2021 Elsevier Ltd


  • The impact of spiro-OMeTAD photodoping on the reversible light-induced transients of perovskite solar cells

    Tan B., Raga S.R., Rietwyk K.J., Lu J., Fürer S.O., Griffith J.C., Cheng Y.-B., Bach U. Nano Energy; 82 (105658) 2021. 10.1016/j.nanoen.2020.105658. IF: 16.602

    Nanostructured Materials for Photovoltaic Energy

    Hole transporting materials (HTMs) play essential roles in facilitating hole extraction and suppressing recombination in lead halide perovskite solar cells (PSCs). High levels of p-doping in HTMs is necessary for achieving high device performance, attributed to an increased electrical conductivity. In this work, we provide evidences that the poor performance of PSCs with low levels of doping (i.e., 4 mol% spiro-OMeTAD+) in spiro-OMeTAD is mainly caused by the presence of a Schottky barrier at the perovskite/spiro-OMeTAD interface, hampering hole injection. Under continuous illumination at open-circuit condition, the barrier gradually diminishes, increasing the PSC power conversion efficiency by 70-fold after 7 h. This process is completely reversible, returning to the initial poor performance after dark storage. We attribute this improvement in performance to a gradual photodoping of spiro-OMeTAD, triggered by the transfer of photogenerated holes and mediated by the slow migration of halide anions from perovskite to compensate the newly formed spiro-OMeTAD+. In-situ parallel analyses with impedance spectroscopy (IS) and photoluminescence are employed to gain insights into the charge dynamics along with light soaking. We find that the Schottky barrier resistance overlays with the recombination signal at the high frequency arc of IS, having important implications for the IS data analysis for PSCs. The work elucidates a major mechanism causing the slow efficiency variations during light/dark cycling, commonly observed in PSCs, which complicates the determination of long-term stability. © 2021 Elsevier Ltd


  • Thermal transport in amorphous graphene with varying structural quality

    Antidormi A., Colombo L., Roche S. 2D Materials; 8 (1, 015028) 2021. 10.1088/2053-1583/abc7f8. IF: 7.140

    Theoretical and Computational Nanoscience

    The synthesis of wafer-scale two-dimensional amorphous carbon monolayers has been recently demonstrated. This material presents useful properties when integrated as coating of metals, semiconductors or magnetic materials, such as enabling efficient atomic layer deposition and hence fostering the development of ultracompact technologies. Here we propose a characterization of how the structural degree of amorphousness of such carbon membranes could be controlled by the crystal growth temperature. We also identify how energy is dissipated in this material by a systematic analysis of emerging vibrational modes whose localization increases with the loss of spatial symmetries, resulting in a tunable thermal conductivity varying by more than two orders of magnitude. Our simulations provide some recipe to design most suitable 'amorphous graphene' based on the target applications such as ultrathin heat spreaders, energy harvesters or insulating thermal barriers. © 2020 IOP Publishing Ltd.


  • Thiol-yne click reaction: an interesting way to derive thiol-provided catechols

    Nador F., Mancebo-Aracil J., Zanotto D., Ruiz-Molina D., Radivoy G. RSC Advances; 11 (4): 2074 - 2082. 2021. 10.1039/d0ra09687c. IF: 3.119

    Nanostructured Functional Materials

    The hydrothiolation of activated alkynes is presented as an attractive and powerful way to functionalize thiols bearing catechols. The reaction was promoted by a heterogeneous catalyst composed of copper nanoparticles supported on TiO2 (CuNPs/TiO2) in 1,2-dichloroethane (1,2-DCE) under heating at 80 °C. The catalyst could be recovered and reused in three consecutive cycles, showing a slight decrease in its catalytic activity. Thiol derivatives bearing catechol moieties, obtained through a versatile Michael addition, were reacted with different activated alkynes, such as methyl propiolate, propiolic acid, propiolamide or 2-ethynylpyridine. The reaction was shown to be regio- and stereoselective towards anti-Markovnikov Z-vinyl sulfide in most cases studied. Finally, some catechol derivatives obtained were tested as ligands in the preparation of coordination polymer nanoparticles (CNPs), by taking the advantage of their different coordination sites with metals such as iron and cobalt. © 2021 The Royal Society of Chemistry.


  • Trends in Micro-/Nanorobotics: Materials Development, Actuation, Localization, and System Integration for Biomedical Applications

    Wang B., Kostarelos K., Nelson B.J., Zhang L. Advanced Materials; 33 (4, 2002047) 2021. 10.1002/adma.202002047. IF: 27.398

    Nanomedicine

    Micro-/nanorobots (m-bots) have attracted significant interest due to their suitability for applications in biomedical engineering and environmental remediation. Particularly, their applications in in vivo diagnosis and intervention have been the focus of extensive research in recent years with various clinical imaging techniques being applied for localization and tracking. The successful integration of well-designed m-bots with surface functionalization, remote actuation systems, and imaging techniques becomes the crucial step toward biomedical applications, especially for the in vivo uses. This review thus addresses four different aspects of biomedical m-bots: design/fabrication, functionalization, actuation, and localization. The biomedical applications of the m-bots in diagnosis, sensing, microsurgery, targeted drug/cell delivery, thrombus ablation, and wound healing are reviewed from these viewpoints. The developed biomedical m-bot systems are comprehensively compared and evaluated based on their characteristics. The current challenges and the directions of future research in this field are summarized. © 2020 Wiley-VCH GmbH


  • Ultrasound-assisted exfoliation of a layered 2D coordination polymer with HER electrocatalytic activity

    Contreras-Pereda N., Moghzi F., Baselga J., Zhong H., Janczak J., Soleimannejad J., Dong R., Ruiz-Molina D. Ultrasonics Sonochemistry; 70 (105292) 2021. 10.1016/j.ultsonch.2020.105292. IF: 6.513

    Nanostructured Functional Materials

    Large blue rectangular crystals of the 2D layered coordination polymer 1 have been obtained. The interest for this complex is two-fold. First, complex 1 is made of 2D layers packing along the (0–11) direction favored by the presence of lattice and coordinated water molecules. And second, nanostructures that could be derived by delamination are potentially suitable for catalytic purposes. Therefore it represents an excellent example to study the role of interlayer solvent molecules on the ultrasound-assisted delamination of functionally-active 2D metal-organic frameworks in water, a field of growing interest. With this aim, ultrasound-assisted delamination of the crystals was optimized with time, leading to stable nanosheet colloidal water suspensions with very homogeneous dimensions. Alternative bottom-up synthesis of related nanocrystals under ultrasound sonication yielded similar shaped crystals with much higher size dispersions. Finally, experimental results evidence that the nanostructures have higher catalytic activities in comparison to their bulk counterparts, due to larger metallic center exposition. These outcomes confirm that the combination of liquid phase exfoliation and a suitable synthetic design of 2D coordination polymers represents a very fruitful approach for the synthesis of functional nanosheets with an enhancement of catalytic active sites, and in general, with boosted functional properties. © 2020 Elsevier B.V.


  • Unraveling the Key Relationship Between Perovskite Capacitive Memory, Long Timescale Cooperative Relaxation Phenomena, and Anomalous J–V Hysteresis

    Hernández-Balaguera E., del Pozo G., Arredondo B., Romero B., Pereyra C., Xie H., Lira-Cantú M. Solar RRL; 2021. 10.1002/solr.202000707. IF: 7.527

    Nanostructured Materials for Photovoltaic Energy

    Capacitive response at long time scales seems to remain an elusive feature in the analysis of the electrical properties of perovskite-based solar cells. It belongs to one of the critical anomalous effects that arises from the characteristic phenomenology of this type of emerging photovoltaic devices. Thereby, accurately deducing key capacitance feature of new light harvesting perovskites from electrical measurements represents a significant challenge regarding the interpretation of physical processes and the control of undesired mechanisms, such as slow dynamic effects and/or current density–voltage (J–V) hysteresis. Herein, it is shown that long timescale mechanisms that give rise to hysteresis in stable and high-efficiency quadruple-cation perovskites are not due to a classical capacitive behavior in the sense of ideal charge accumulation processes. Instead, it is a phenomenological consequence of slow memory-based capacitive currents and the underlying cooperative relaxations. A fractional dynamics approach, based on the idea of capacitance distribution in perovskite devices, reliably models the slow transient phenomena and the consequent scan-rate- and bias-dependent hysteresis. Observable for a wide variety of photovoltaic halide perovskites, distributed capacitive effects are rather universal anomalous phenomena, which can be related to the long-time electrical response and hysteresis. © 2021 Wiley-VCH GmbH