ICN2 Publications


  • 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

    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. ©

  • A First-Principles Investigation on the Electronic and Mechanical Properties of 1T TiSe2Multilayers for Energy Storage

    Antonio J.E., Cervantes J.M., Rosas-Huerta J.L., Pilo J., Carvajal E., Escamilla R. Journal of the Electrochemical Society; 168 (3, 030531) 2021. 10.1149/1945-7111/abed29. IF: 3.721

    Theory and Simulation

    In this work, the electronic and mechanical properties of bulk TiSe2 were studied, and the effects of confinement on the compound, into mono-, bi-, and tri-layered systems, on the electronic and mechanical properties using DFT-based calculations within the Generalized Gradient Approximation (GGA) using Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. Lithium atoms were placed at different adsorption sites of the TiSe2 monolayer to study the consequences on the electronic and mechanical properties and to identify the most favourable adsorption site for Li in the TiSe2 systems. Mono -, bi-, and tri-layered systems have associated a metallic behaviour, similar to the bulk material. Young's modulus for mono-, bi-, and tri-layered systems show similar behaviour to the bulk case. On the other hand, monolayers with Li are metallic when Li atoms are placed at the surface; and this behaviour could be favourable to facilitate electronic transport by the monolayer. Finally, the mechanical properties analysis supported that the better adsorption sites are those labelled as Top and Hollow. © 2021 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

  • A generalized approach for evaluating the mechanical properties of polymer nanocomposites reinforced with spherical fillers

    Martinez-Garcia J.C., Serraïma-Ferrer A., Lopeandía-Fernández A., Lattuada M., Sapkota J., Rodríguez-Viejo J. Nanomaterials; 11 (4, 830) 2021. 10.3390/nano11040830. IF: 4.324

    Thermal Properties of Nanoscale Materials

    In this work, the effective mechanical reinforcement of polymeric nanocomposites containing spherical particle fillers is predicted based on a generalized analytical three-phase-series-parallel model, considering the concepts of percolation and the interfacial glassy region. While the concept of percolation is solely taken as a contribution of the filler-network, we herein show that the glassy interphase between filler and matrix, which is often in the nanometers range, is also to be considered while interpreting enhanced mechanical properties of particulate filled polymeric nanocomposites. To demonstrate the relevance of the proposed generalized equation, we have fitted several experimental results which show a good agreement with theoretical predictions. Thus, the approach presented here can be valuable to elucidate new possible conceptual routes for the creation of new materials with fundamental technological applications and can open a new research avenue for future studies. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • A high-entropy manganite in an ordered nanocomposite for long-term application in solid oxide cells

    Baiutti F., Chiabrera F., Acosta M., Diercks D., Parfitt D., Santiso J., Wang X., Cavallaro A., Morata A., Wang H., Chroneos A., MacManus-Driscoll J., Tarancon A. Nature Communications; 12 (1, 2660) 2021. 10.1038/s41467-021-22916-4. IF: 12.121

    Nanomaterials Growth Unit

    The implementation of nano-engineered composite oxides opens up the way towards the development of a novel class of functional materials with enhanced electrochemical properties. Here we report on the realization of vertically aligned nanocomposites of lanthanum strontium manganite and doped ceria with straight applicability as functional layers in high-temperature energy conversion devices. By a detailed analysis using complementary state-of-the-art techniques, which include atom-probe tomography combined with oxygen isotopic exchange, we assess the local structural and electrochemical functionalities and we allow direct observation of local fast oxygen diffusion pathways. The resulting ordered mesostructure, which is characterized by a coherent, dense array of vertical interfaces, shows high electrochemically activity and suppressed dopant segregation. The latter is ascribed to spontaneous cationic intermixing enabling lattice stabilization, according to density functional theory calculations. This work highlights the relevance of local disorder and long-range arrangements for functional oxides nano-engineering and introduces an advanced method for the local analysis of mass transport phenomena. © 2021, The Author(s).

  • A singlet-triplet hole spin qubit in planar Ge

    Jirovec D., Hofmann A., Ballabio A., Mutter P.M., Tavani G., Botifoll M., Crippa A., Kukucka J., Sagi O., Martins F., Saez-Mollejo J., Prieto I., Borovkov M., Arbiol J., Chrastina D., Isella G., Katsaros G. Nature Materials; 2021. 10.1038/s41563-021-01022-2. IF: 38.663

    Advanced Electron Nanoscopy

    Spin qubits are considered to be among the most promising candidates for building a quantum processor. Group IV hole spin qubits are particularly interesting owing to their ease of operation and compatibility with Si technology. In addition, Ge offers the option for monolithic superconductor–semiconductor integration. Here, we demonstrate a hole spin qubit operating at fields below 10 mT, the critical field of Al, by exploiting the large out-of-plane hole g-factors in planar Ge and by encoding the qubit into the singlet-triplet states of a double quantum dot. We observe electrically controlled g-factor difference-driven and exchange-driven rotations with tunable frequencies exceeding 100 MHz and dephasing times of 1 μs, which we extend beyond 150 μs using echo techniques. These results demonstrate that Ge hole singlet-triplet qubits are competing with state-of-the-art GaAs and Si singlet-triplet qubits. In addition, their rotation frequencies and coherence are comparable with those of Ge single spin qubits, but singlet-triplet qubits can be operated at much lower fields, emphasizing their potential for on-chip integration with superconducting technologies. © 2021, The Author(s), under exclusive licence to Springer Nature Limited.

  • A three-shell supramolecular complex enables the symmetry-mismatched chemo- and regioselective bis-functionalization of C60

    Ubasart E., Borodin O., Fuertes-Espinosa C., Xu Y., García-Simón C., Gómez L., Juanhuix J., Gándara F., Imaz I., Maspoch D., von Delius M., Ribas X. Nature Chemistry; 13 (5): 420 - 427. 2021. 10.1038/s41557-021-00658-6. IF: 21.687

    Supramolecular NanoChemistry and Materials

    Molecular Russian dolls (matryoshkas) have proven useful for testing the limits of preparative supramolecular chemistry but applications of these architectures to problems in other fields are elusive. Here we report a three-shell, matryoshka-like complex—in which C60 sits inside a cycloparaphenylene nanohoop, which in turn is encapsulated inside a self-assembled nanocapsule—that can be used to address a long-standing challenge in fullerene chemistry, namely the selective formation of a particular fullerene bis-adduct. Spectroscopic evidence indicates that the ternary complex is sufficiently stable in solution for the two outer shells to affect the addition chemistry of the fullerene guest. When the complex is subjected to Bingel cyclopropanation conditions, the exclusive formation of a single trans-3 fullerene bis-adduct was observed in a reaction that typically yields more than a dozen products. The selectivity facilitated by this matryoshka-like approach appears to be a general phenomenon and could be useful for applications where regioisomerically pure C60 bis-adducts have been shown to have superior properties compared with isomer mixtures. [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer Nature Limited.

  • Additive engineering for stable halide perovskite solar cells

    Pereyra C., Xie H., Lira-Cantu M. Journal of Energy Chemistry; 60: 599 - 634. 2021. 10.1016/j.jechem.2021.01.037. IF: 7.216

    Nanostructured Materials for Photovoltaic Energy

    Halide perovskite solar cells (PSCs) have already demonstrated power conversion efficiencies above 25%, which makes them one of the most attractive photovoltaic technologies. However, one of the main bottlenecks towards their commercialization is their long-term stability, which should exceed the 20-year mark. Additive engineering is an effective pathway for the enhancement of device lifetime. Additives applied as organic or inorganic compounds, improve crystal grain growth enhancing power conversion efficiency. The interaction of their functional groups with the halide perovskite (HP) absorber, as well as with the transport layers, results in defect passivation and ion immobilization improving device performance and stability. In this review, we briefly summarize the different types of additives recently applied in PSC to enhance not only efficiency but also long-term stability. We discuss the different mechanism behind additive engineering and the role of the functional groups of these additives for defect passivation. Special emphasis is given to their effect on the stability of PSCs under environmental conditions such as humidity, atmosphere, light irradiation (UV, visible) or heat, taking into account the recently reported ISOS protocols. We also discuss the relation between deep-defect passivation, non-radiative recombination and device efficiency, as well as the possible relation between shallow-defect passivation, ion immobilization and device operational stability. Finally, insights into the challenge and criteria for additive selection are provided for the further stability enhancement of PSCs. © 2021 Science Press

  • Adenoviral Mediated Delivery of OSKM Factors Induces Partial Reprogramming of Mouse Cardiac Cells In Vivo

    Kisby T., de Lázaro I., Fisch S., Cartwright E.J., Cossu G., Kostarelos K. Advanced Therapeutics; 4 (2, 2000141) 2021. 10.1002/adtp.202000141. IF: 0.000


    The induction of in vivo reprogramming toward pluripotency has been demonstrated in several tissues utilizing either transgenic inducible mice or gene delivery approaches. However, the effects of exogenous reprogramming factor expression in the mammalian heart have not been previously reported. The present study aims to investigate the response of cardiac cells to ectopic Oct3/4, Sox2, Klf4, and cMyc (OSKM) expression in vivo using a non-integrating adenoviral vector. Direct intramyocardial injection of this vector achieves effective and transient OSKM overexpression in the healthy heart and after myocardial infarction. The expression of these factors induces transient upregulation of a number of endogenous pluripotency (endo-Oct3/4, Gdf3) and reprogramming related (Cdh1, Fut4) genes, confirming the induction of cell reprogramming. Despite the initiation of reprogramming, markers of fully de-differentiated cells including Nanog remain silenced, consistent with a partially reprogrammed state. Furthermore, no indications of tumorigenesis or teratoma formation are observed. Overall, these data suggest that adenoviral mediated OSKM delivery can be utilized to induce partial in vivo reprogramming. However, the absence of any clear regenerative effects after myocardial infarction indicates that further optimization of vector mediated reprogramming strategies is essential to overcome barriers to therapeutic efficacy. © 2020 The Authors. Advanced Therapeutics published by Wiley-VCH GmbH

  • Advanced Data Encryption ​using 2D Materials

    Wen C., Li X., Zanotti T., Puglisi F.M., Shi Y., Saiz F., Antidormi A., Roche S., Zheng W., Liang X., Hu J., Duhm S., Roldan J.B., Wu T., Chen V., Pop E., Garrido B., Zhu K., Hui F., Lanza M. Advanced Materials; 2021. 10.1002/adma.202100185. IF: 27.398

    Theoretical and Computational Nanoscience

    Advanced data encryption requires the use of true random number generators (TRNGs) to produce unpredictable sequences of bits. TRNG circuits with high degree of randomness and low power consumption may be fabricated by using the random telegraph noise (RTN) current signals produced by polarized metal/insulator/metal (MIM) devices as entropy source. However, the RTN signals produced by MIM devices made of traditional insulators, i.e., transition metal oxides like HfO2 and Al2O3, are not stable enough due to the formation and lateral expansion of defect clusters, resulting in undesired current fluctuations and the disappearance of the RTN effect. Here, the fabrication of highly stable TRNG circuits with low power consumption, high degree of randomness (even for a long string of 224 − 1 bits), and high throughput of 1 Mbit s−1 by using MIM devices made of multilayer hexagonal boron nitride (h-BN) is shown. Their application is also demonstrated to produce one-time passwords, which is ideal for the internet-of-everything. The superior stability of the h-BN-based TRNG is related to the presence of few-atoms-wide defects embedded within the layered and crystalline structure of the h-BN stack, which produces a confinement effect that avoids their lateral expansion and results in stable operation. © 2021 Wiley-VCH GmbH

  • An inverted honeycomb plasmonic lattice as an efficient refractive index sensor

    Rodríguez-álvarez J., Gnoatto L., Martínez-Castells M., Guerrero A., Borrisé X., Rodríguez A.F., Batlle X., Labarta A. Nanomaterials; 11 (5, 1217) 2021. 10.3390/nano11051217. IF: 4.324

    Nanofabrication Facility

    We present an efficient refractive index sensor consisting of a heterostructure that contains an Au inverted honeycomb lattice as a main sensing element. Our design aims at maximizing the out-of-plane near-field distributions of the collective modes of the lattice mapping the sensor sur-roundings. These modes are further enhanced by a patterned SiO2 layer with the same inverted honeycomb lattice, an SiO2 spacer, and an Au mirror underneath the Au sensing layer that contrib-ute to achieving a high performance. The optical response of the heterostructure was studied by numerical simulation. The results corresponding to one of the collective modes showed high sensitivity values ranging from 99 to 395 nm/RIU for relatively thin layers of test materials within 50 and 200 nm. In addition, the figure of merit of the sensor detecting slight changes of the refractive index of a water medium at a fixed wavelength was as high as 199 RIU−1. As an experimental proof of concept, the heterostructure was manufactured by a simple method based on electron beam lithography and the measured optical response reproduces the simulations. This work paves the way for improving both the sensitivity of plasmonic sensors and the signal of some enhanced surface spec-troscopies. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Antibacterial activity testing methods for hydrophobic patterned surfaces

    Perez-Gavilan A., de Castro J.V., Arana A., Merino S., Retolaza A., Alves S.A., Francone A., Kehagias N., Sotomayor-Torres C.M., Cocina D., Mortera R., Crapanzano S., Pelegrín C.J., Garrigos M.C., Jiménez A., Galindo B., Araque M.C., Dykeman D., Neves N.M., Marimón J.M. Scientific Reports; 11 (1, 6675) 2021. 10.1038/s41598-021-85995-9. IF: 3.998

    Phononic and Photonic Nanostructures

    One strategy to decrease the incidence of hospital-acquired infections is to avoid the survival of pathogens in the environment by the development of surfaces with antimicrobial activity. To study the antibacterial behaviour of active surfaces, different approaches have been developed of which ISO 22916 is the standard. To assess the performance of different testing methodologies to analyse the antibacterial activity of hydrophobic surface patterned plastics as part of a Horizon 2020 European research project. Four different testing methods were used to study the antibacterial activity of a patterned film, including the ISO 22916 standard, the immersion method, the touch-transfer inoculation method, and the swab inoculation method, this latter developed specifically for this project. The non-realistic test conditions of the ISO 22916 standard showed this method to be non-appropriate in the study of hydrophobic patterned surfaces. The immersion method also showed no differences between patterned films and smooth controls due to the lack of attachment of testing bacteria on both surfaces. The antibacterial activity of films could be demonstrated by the touch-transfer and the swab inoculation methods, that more precisely mimicked the way of high-touch surfaces contamination, and showed to be the best methodologies to test the antibacterial activity of patterned hydrophobic surfaces. A new ISO standard would be desirable as the reference method to study the antibacterial behaviour of patterned surfaces. © 2021, The Author(s).

  • 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

  • Antitumour activity of coordination polymer nanoparticles

    Suárez-García S., Solórzano R., Alibés R., Busqué F., Novio F., Ruiz-Molina D. Coordination Chemistry Reviews; 441 (213977) 2021. 10.1016/j.ccr.2021.213977. IF: 15.367

    Nanostructured Functional Materials

    Nanoscale coordination polymers (NCPs) have fascinated researchers over the last years. Their intrinsic theranostic properties of metal ions and organic ligands, the encapsulation of several drugs/biomolecules with excellent yields and the surface functionalisation, enhancing their biocompatibility and targeting, have remarkably impacted in prospective drug delivery alternatives in medicine. Moreover, the properties and characteristics of these nanoparticles (NPs) can be fine-tuned thanks to the synthetic flexibility of coordination chemistry. For all these reasons, the number of examples published has grown exponentially over the last years, embracing different disciplines such as molecular electronics, sensors or nanomedicine, among others. Specifically, significant advances in antitumoural applications are reported, one of the areas where this novel family of NPs has experienced a considerable advance. NCPs have accomplished a high sophistication degree and efficiency as theranostic nanoplatforms (i.e., drug delivery carriers and bioimaging probes) with long residence time in the bloodstream, targeting capacities and remarkable cellular internalisation. In this review, an introduction emphasizing the advantages of NPs for cancer treatment is included. Later on, the most representative examples of NCPs for antitumoural applications are described grouped into six mean representative areas: i) encapsulation approaches, ii) stimuli-responsive NCPs, iii) metal chemotherapy, iv) photodynamic therapy (PDT), v) unconventional therapeutic approaches and vi) theranostics. Particular emphasis is given to understand the encapsulation/release properties of these particles at the nanoscale and their interaction with biological environments, highlighting any limitation and challenges that these systems are facing from a clinical translation perspective and envisioning possible future trends and areas that will deserve further attention for the following years. © 2021 The Authors

  • Approaching ultrathin VO2films on sapphire (001) substrates by biased reactive sputtering: Characteristic morphology and its effect on the infrared-light switching

    Okimura K., Sakai J., Kuwahara M., Zaghrioui M., Uehara Y. Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films; 39 (4, 043401) 2021. 10.1116/6.0001023. IF: 2.166

    Oxide Nanophysics

    Ultrathin VO2 films with insulator-metal transition (IMT) were successfully fabricated on sapphire (001) substrates by utilizing radio frequency-biased reactive sputtering. We realized a 6 nm-thick VO2 film that shows resistance change over 2 orders of magnitude. Microscopic observations combined with energy dispersive x-ray analyses revealed characteristic networking morphology in VO2 films with thickness up to around 10 nm. It was found through micro-Raman analyses that a 30 nm-thick film possessed flat surface and ordered lattice with strong in-plane tensile stress. We evaluated the thickness dependence of optical switching performance for infrared-light. The results suggest that the thickness of the VO2 films should be carefully selected for realizing required performances of optical switching, which depends on not only IMT but also characteristic morphological aspects. © 2021 Author(s).

  • 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

    Theory and Simulation

    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

  • Balancing Charge Extraction for Efficient Back-Contact Perovskite Solar Cells by Using an Embedded Mesoscopic Architecture

    Lin X., Lu J., Raga S.R., McMeekin D.P., Ou Q., Scully A.D., Tan B., Chesman A.S.R., Deng S., Zhao B., Cheng Y.-B., Bach U. Advanced Energy Materials; 11 (21, 2100053) 2021. 10.1002/aenm.202100053. IF: 25.245

    Nanostructured Materials for Photovoltaic Energy

    As the performance of organic–inorganic halide perovskite solar cells approaches their practical limits, the use of back-contact architectures, which eliminate parasitic light absorption, provides an effective route toward higher device efficiencies. However, a poor understanding of the underlying device physics has limited further performance improvements. Here a mesoporous charge-transporting layer is introduced into quasi-interdigitated back-contact perovskite devices and the charge extraction behavior with an increased interfacial contact area is studied. The results show that the incorporation of a thin mesoporous titanium dioxide layer significantly shortens the charge-transfer lifetime and results in more efficient and balanced charge extraction dynamics. A high short-circuit current density of 21.3 mA cm–2 is achieved using a polycrystalline perovskite layer on a mesoscopic quasi-interdigitated back-contact electrode, a record for this type of device architecture. © 2021 Wiley-VCH GmbH

  • Bioinspired Theranostic Coordination Polymer Nanoparticles for Intranasal Dopamine Replacement in Parkinson's Disease

    García-Pardo J., Novio F., Nador F., Cavaliere I., Suárez-García S., Lope-Piedrafita S., Candiota A.P., Romero-Gimenez J., Rodríguez-Galván B., Bové J., Vila M., Lorenzo J., Ruiz-Molina D. ACS Nano; 2021. 10.1021/acsnano.1c00453. IF: 14.588

    Nanostructured Functional Materials

    Dopamine (DA) is one of the main neurotransmitters found in the central nervous system and has a vital role in the function of dopaminergic (DArgic) neurons. A progressive loss of this specific subset of cells is one of the hallmarks of age-related neurodegenerative disorders such as Parkinson's disease (PD). Symptomatic therapy for PD has been centered in the precursor l-DOPA administration, an amino acid precursor of DA that crosses the blood-brain barrier (BBB) while DA does not, although this approach presents medium- to long-term side effects. To overcome this limitation, DA-nanoencapsulation therapies are actively being searched as an alternative for DA replacement. However, overcoming the low yield of encapsulation and/or poor biodistribution/bioavailability of DA is still a current challenge. Herein, we report the synthesis of a family of neuromelanin bioinspired polymeric nanoparticles. Our system is based on the encapsulation of DA within nanoparticles through its reversible coordination complexation to iron metal nodes polymerized with a bis-imidazol ligand. Our methodology, in addition to being simple and inexpensive, results in DA loading efficiencies of up to 60%. In vitro, DA nanoscale coordination polymers (DA-NCPs) exhibited lower toxicity, degradation kinetics, and enhanced uptake by BE(2)-M17 DArgic cells compared to free DA. Direct infusion of the particles in the ventricle of rats in vivo showed a rapid distribution within the brain of healthy rats, leading to an increase in striatal DA levels. More importantly, after 4 days of nasal administrations with DA-NCPs equivalent to 200 μg of the free drug per day, the number and duration of apomorphine-induced rotations was significantly lower from that in either vehicle or DA-treated rats performed for comparison purposes. Overall, this study demonstrates the advantages of using nanostructured DA for DA-replacement therapy. ©

  • Buttermilk as encapsulating agent: Effect of ultra-high-pressure homogenization on chia oil-in-water liquid emulsion formulations for spray drying

    Aghababaei F., Cano-Sarabia M., Trujillo A.J., Quevedo J.M., Ferragut V. Foods; 10 (5, 1059) 2021. 10.3390/foods10051059. IF: 4.092

    Supramolecular NanoChemistry and Materials

    Functional foods are highly demanded by consumers. Omega-3 rich oil and commercial buttermilk (BM), as functional components, used in combination to produce emulsions for further drying may facilitate the incorporation to foods. Ultra-high-pressure homogenization (UHPH) has a great potential for technological and nutritional aspects in emulsions production. The present study aimed to examine the potential improvement of UHPH technology in producing buttermilk-stabilized omega-3 rich emulsions (BME) for further drying, compared with conventional homogenization. Oil-in-water emulsions formulated with 10% chia: sunflower oil (50:50); 30% maltodextrin and 4 to 7% buttermilk were obtained by using conventional homogenization at 30 MPa and UHPH at 100 and 200 MPa. Particle size analysis, rheological evaluation, colloidal stability, zeta-potential measurement, and microstructure observations were performed in the BME. Subsequent spray drying of emulsions were made. As preliminary approximation for evaluating differences in the homogenization technology applied, encapsulation efficiency and morphological characteristics of on spray-dried emulsions (SDE) containing 21.3 to 22.7% oil content (dry basis) were selected. This study addresses the improvement in stability of BME treated by UHPH when compared to conventional homogenization and the beneficial consequences in encapsulation efficiency and morphology of SDE. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Cerium oxide nanoparticles: A new therapeutic tool in liver diseases

    Casals G., Perramón M., Casals E., Portolés I., Fernández-Varo G., Morales-Ruiz M., Puntes V., Jiménez W. Antioxidants; 10 (5, 660) 2021. 10.3390/antiox10050660. IF: 5.014

    Inorganic Nanoparticles

    Oxidative stress induced by the overproduction of free radicals or reactive oxygen species (ROS) has been considered as a key pathogenic mechanism contributing to the initiation and progression of injury in liver diseases. Consequently, during the last few years antioxidant substances, such as superoxide dismutase (SOD), resveratrol, colchicine, eugenol, and vitamins E and C have received increasing interest as potential therapeutic agents in chronic liver diseases. These substances have demonstrated their efficacy in equilibrating hepatic ROS metabolism and thereby improving liver functionality. However, many of these agents have not successfully passed the scrutiny of clinical trials for the prevention and treatment of various diseases, mainly due to their unspecificity and consequent uncontrolled side effects, since a minimal level of ROS is needed for normal functioning. Recently, cerium oxide nanoparticles (CeO2 NPs) have emerged as a new powerful antioxidant agent with therapeutic properties in experimental liver disease. CeO2 NPs have been reported to act as a ROS and reactive nitrogen species (RNS) scavenger and to have multi-enzyme mimetic activity, including SOD activity (deprotionation of superoxide anion into oxygen and hydrogen peroxide), catalase activity (conversion of hydrogen peroxide into oxygen and water), and peroxidase activity (reducing hydrogen peroxide into hydroxyl radicals). Consequently, the beneficial effects of CeO2 NPs treatment have been reported in many different medical fields other than hepatology, including neurology, ophthalmology, cardiology, and oncology. Unlike other antioxidants, CeO2 NPs are only active at pathogenic levels of ROS, being inert and innocuous in healthy cells. In the current article, we review the potential of CeO2 NPs in several experimental models of liver disease and their safety as a therapeutic agent in humans as well. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Characterization of charge states in conducting organic nanoparticles by X-ray photoemission spectroscopy

    Fraxedas J., Vollmer A., Koch N., de Caro D., Jacob K., Faulmann C., Valade L. Materials; 14 (8, 2058) 2021. 10.3390/ma14082058. IF: 3.057

    Thermal Properties of Nanoscale Materials

    The metallic and semiconducting character of a large family of organic materials based on the electron donor molecule tetrathiafulvalene (TTF) is rooted in the partial oxidation (charge transfer or mixed valency) of TTF derivatives leading to partially filled molecular orbital-based electronic bands. The intrinsic structure of such complexes, with segregated donor and acceptor molecular chains or planes, leads to anisotropic electronic properties (quasi one-dimensional or two-dimensional) and morphology (needle-like or platelet-like crystals). Recently, such materials have been synthesized as nanoparticles by intentionally frustrating the intrinsic anisotropic growth. X-ray photoemission spectroscopy (XPS) has emerged as a valuable technique to characterize the transfer of charge due to its ability to discriminate the different chemical environments or electronic configurations manifested by chemical shifts of core level lines in high-resolution spectra. Since the photoemission process is inherently fast (well below the femtosecond time scale), dynamic processes can be efficiently explored. We determine here the fingerprint of partial oxidation on the photoemission lines of nanoparticles of selected TTF-based conductors. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Characterization of optogenetically-induced cortical spreading depression in awake mice using graphene micro-transistor arrays

    Masvidal-Codina E., Smith T.M., Rathore D., Gao Y., Illa X., Prats-Alfonso E., Corro E.D., Calia A.B., Rius G., Martin-Fernandez I., Guger C., Reitner P., Villa R., Garrido J.A., Guimera-Brunet A., Wykes R.C. Journal of Neural Engineering; 18 (5, 055002) 2021. 10.1088/1741-2552/abecf3. IF: 4.141

    Advanced Electronic Materials and Devices

    Objective. The development of experimental methodology utilizing graphene micro-transistor arrays to facilitate and advance translational research into cortical spreading depression (CSD) in the awake brain. Approach. CSDs were reliably induced in awake nontransgenic mice using optogenetic methods. High-fidelity DC-coupled electrophysiological mapping of propagating CSDs was obtained using flexible arrays of graphene soultion-gated field-effect transistors (gSGFETs). Main results. Viral vectors targetted channelrhopsin expression in neurons of the motor cortex resulting in a transduction volume 1 mm3. 5-10 s of continous blue light stimulation induced CSD that propagated across the cortex at a velocity of 3.0 0.1 mm min-1. Graphene micro-transistor arrays enabled high-density mapping of infraslow activity correlated with neuronal activity suppression across multiple frequency bands during both CSD initiation and propagation. Localized differences in the CSD waveform could be detected and categorized into distinct clusters demonstrating the spatial resolution advantages of DC-coupled recordings. We exploited the reliable and repeatable induction of CSDs using this preparation to perform proof-of-principle pharmacological interrogation studies using NMDA antagonists. MK801 (3 mg kg-1) suppressed CSD induction and propagation, an effect mirrored, albeit transiently, by ketamine (15 mg kg-1), thus demonstrating this models' applicability as a preclinical drug screening platform. Finally, we report that CSDs could be detected through the skull using graphene micro-transistors, highlighting additional advantages and future applications of this technology. Significance. CSD is thought to contribute to the pathophysiology of several neurological diseases. CSD research will benefit from technological advances that permit high density electrophysiological mapping of the CSD waveform and propagation across the cortex. We report an in vivo assay that permits minimally invasive optogenetic induction, combined with multichannel DC-coupled recordings enabled by gSGFETs in the awake brain. Adoption of this technological approach could facilitate and transform preclinical investigations of CSD in disease relevant models. © 2021 The Author(s). Published by IOP Publishing Ltd.

  • 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.

  • Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes

    Gao R., Fernandez A., Chakraborty T., Luo A., Pesquera D., Das S., Velarde G., Thoréton V., Kilner J., Ishihara T., Nemšák S., Crumlin E.J., Ertekin E., Martin L.W. Advanced Materials; 33 (20, 2100977) 2021. 10.1002/adma.202100977. IF: 27.398

    Oxide Nanophysics

    Solid–gas interactions at electrode surfaces determine the efficiency of solid-oxide fuel cells and electrolyzers. Here, the correlation between surface–gas kinetics and the crystal orientation of perovskite electrodes is studied in the model system La0.8Sr0.2Co0.2Fe0.8O3. The gas-exchange kinetics are characterized by synthesizing epitaxial half-cell geometries where three single-variant surfaces are produced [i.e., La0.8Sr0.2Co0.2Fe0.8O3/La0.9Sr0.1Ga0.95Mg0.05O3−δ/SrRuO3/SrTiO3 (001), (110), and (111)]. Electrochemical impedance spectroscopy and electrical conductivity relaxation measurements reveal a strong surface-orientation dependency of the gas-exchange kinetics, wherein (111)-oriented surfaces exhibit an activity >3-times higher as compared to (001)-oriented surfaces. Oxygen partial pressure ((Formula presented.))-dependent electrochemical impedance spectroscopy studies reveal that while the three surfaces have different gas-exchange kinetics, the reaction mechanisms and rate-limiting steps are the same (i.e., charge-transfer to the diatomic oxygen species). First-principles calculations suggest that the formation energy of vacancies and adsorption at the various surfaces is different and influenced by the surface polarity. Finally, synchrotron-based, ambient-pressure X-ray spectroscopies reveal distinct electronic changes and surface chemistry among the different surface orientations. Taken together, thin-film epitaxy provides an efficient approach to control and understand the electrode reactivity ultimately demonstrating that the (111)-surface exhibits a high density of active surface sites which leads to higher activity. © 2021 Wiley-VCH GmbH

  • COVID-19 biosensing technologies

    Merkoçi A., Li C.-Z., Lechuga L.M., Ozcan A. Biosensors and Bioelectronics; 178 (113046) 2021. 10.1016/j.bios.2021.113046. IF: 10.257

    NanoBiosensors and Bioanalytical Applications | Nanobioelectronics and Biosensors

    [No abstract available]

  • Cross-species comparisons of nanoparticle interactions with innate immune systems: A methodological review

    Swartzwelter B.J., Mayall C., Alijagic A., Barbero F., Ferrari E., Hernadi S., Michelini S., Pacheco N.I.N., Prinelli A., Swart E., Auguste M. Nanomaterials; 11 (6, 1528) 2021. 10.3390/nano11061528. IF: 4.324

    Inorganic Nanoparticles

    Many components of the innate immune system are evolutionarily conserved and shared across many living organisms, from plants and invertebrates to humans. Therefore, these shared features can allow the comparative study of potentially dangerous substances, such as engineered nanoparticles (NPs). However, differences of methodology and procedure between diverse species and models make comparison of innate immune responses to NPs between organisms difficult in many cases. To this aim, this review provides an overview of suitable methods and assays that can be used to measure NP immune interactions across species in a multidisciplinary approach. The first part of this review describes the main innate immune defense characteristics of the selected models that can be associated to NPs exposure. In the second part, the different modes of exposure to NPs across models (considering isolated cells or whole organisms) and the main endpoints measured are discussed. In this synergistic perspective, we provide an overview of the current state of important cross-disciplinary immunological models to study NP-immune interactions and identify future research needs. As such, this paper could be used as a methodological reference point for future nano-immunosafety studies. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells

    Xie H., Wang Z., Chen Z., Pereyra C., Pols M., Gałkowski K., Anaya M., Fu S., Jia X., Tang P., Kubicki D.J., Agarwalla A., Kim H.-S., Prochowicz D., Borrisé X., Bonn M., Bao C., Sun X., Zakeeruddin S.M., Emsley L., Arbiol J., Gao F., Fu F., Wang H.I., Tielrooij K.-J., Stranks S.D., Tao S., Grätzel M., Hagfeldt A., Lira-Cantu M. Joule; 5 (5): 1246 - 1266. 2021. 10.1016/j.joule.2021.04.003. IF: 29.155

    Ultrafast Dynamics in Nanoscale Systems | Nanostructured Materials for Photovoltaic Energy | Advanced Electron Nanoscopy

    Understanding defects is of paramount importance for the development of stable halide perovskite solar cells (PSCs). However, isolating their distinctive effects on device efficiency and stability is currently a challenge. We report that adding the organic molecule 3-phosphonopropionic acid (H3pp) to the halide perovskite results in unchanged overall optoelectronic performance while having a tremendous effect on device stability. We obtained PSCs with ∼21% efficiency that retain ∼100% of the initial efficiency after 1,000 h at the maximum power point under simulated AM1.5G illumination. The strong interaction between the perovskite and the H3pp molecule through two types of hydrogen bonds (H…I and O…H) leads to shallow point defect passivation that has a significant effect on device stability but not on the non-radiative recombination and device efficiency. We expect that our work will have important implications for the current understanding and advancement of operational PSCs. © 2021 Elsevier Inc.

  • Deep Tissue Translocation of Graphene Oxide Sheets in Human Glioblastoma 3D Spheroids and an Orthotopic Xenograft Model

    de Lázaro I., Sharp P., Gurcan C., Ceylan A., Stylianou M., Kisby T., Chen Y., Vranic S., Barr K., Taheri H., Ozen A., Bussy C., Yilmazer A., Kostarelos K. Advanced Therapeutics; 4 (1, 2000109) 2021. 10.1002/adtp.202000109. IF: 0.000


    Its anatomical localization, a highly heterogeneous and drug-resistant tumor cell population and a “cold” immune microenvironment, all challenge the treatment of glioblastoma. Nanoscale drug delivery systems, including graphene oxide (GO) flakes, may circumvent some of these issues bypassing biological barriers, delivering multiple cargoes to impact several pathways simultaneously, or targeting the immune compartment. Here, the interactions of GO flakes with in vitro (U-87 MG three-dimensional spheroids, without stromal or immune compartments) and in vivo (U-87 MG orthotopic xenograft) models of glioblastoma are investigated. In vitro, GO flakes translocated deeply into the spheroids with little internalization in tumor cells. In vivo, intracranially administered GO also show extensive distribution throughout the tumor and demonstrate no impact on tumor growth and progression for the duration of the study. Internalization within tumor cells is also scarce, with the majority of flakes preferentially taken up by microglia/macrophages. The results indicate that GO flakes could offer deep and homogenous distribution throughout glioblastoma tumors and a means to target their myeloid compartment. Further studies are warranted to investigate the mechanisms of GO flakes transport within the tumor mass and their capacity to deliver bioactive cargoes but, ultimately, this information could inform the development of immunotherapies against glioblastoma. © 2020 The Authors. Published by Wiley-VCH GmbH

  • Design and characterization of high-affinity synthetic peptides as bioreceptors for diagnosis of cutaneous leishmaniasis

    Prada Y.A., Soler M., Guzmán F., Castillo J.J., Lechuga L.M., Mejía-Ospino E. Analytical and Bioanalytical Chemistry; 2021. 10.1007/s00216-021-03424-2. IF: 3.637

    NanoBiosensors and Bioanalytical Applications

    Cutaneous leishmaniasis (CL) is one of the illnesses caused by Leishmania parasite infection, which can be asymptomatic or severe according to the infecting Leishmania strain. CL is commonly diagnosed by directly detecting the parasites or their DNA in tissue samples. New diagnostic methodologies target specific proteins (biomarkers) secreted by the parasite during the infection process. However, specific bioreceptors for the in vivo or in vitro detection of these novel biomarkers are rather limited in terms of sensitivity and specificity. For this reason, we here introduce three novel peptides as bioreceptors for the highly sensitive and selective identification of acid phosphatase (sAP) and proteophosphoglycan (PPG), which have a crucial role in leishmaniasis infection. These high-affinity peptides have been designed from the conservative domains of the lectin family, holding the ability to interact with the biological target and produce the same effect than the original protein. The synthetic peptides have been characterized and the affinity and kinetic constants for their interaction with the targets (sAP and PPG) have been determined by a surface plasmon resonance biosensor. Values obtained for KD are in the nanomolar range, which is comparable to high-affinity antibodies, with the additional advantage of a high biochemical stability and simpler production. Pep2854 exhibited a high affinity for sAP (KD = 1.48 nM) while Pep2856 had a good affinity for PPG (KD 1.76 nM). This study evidences that these peptidomimetics represent a novel alternative tool to the use of high molecular weight proteins for biorecognition in the diagnostic test and biosensor devices for CL. Graphical abstract: [Figure not available: see fulltext.] © 2021, Springer-Verlag GmbH Germany, part of Springer Nature.

  • Disentangling Orbital and Valley Hall Effects in Bilayers of Transition Metal Dichalcogenides

    Cysne T.P., Costa M., Canonico L.M., Nardelli M.B., Muniz R.B., Rappoport T.G. Physical Review Letters; 126 (5, 056601) 2021. 10.1103/PhysRevLett.126.056601. IF: 8.385

    Theoretical and Computational Nanoscience

    It has been recently shown that monolayers of transition metal dichalcogenides (TMDs) in the 2H structural phase exhibit relatively large orbital Hall conductivity plateaus within their energy band gaps, where their spin Hall conductivities vanish [Canonico et al., Phys. Rev. B 101, 161409 (2020)PRBMDO2469-995010.1103/PhysRevB.101.161409; Bhowal and Satpathy, Phys. Rev. B 102, 035409 (2020)PRBMDO2469-995010.1103/PhysRevB.102.035409]. However, since the valley Hall effect (VHE) in these systems also generates a transverse flow of orbital angular momentum, it becomes experimentally challenging to distinguish between the two effects in these materials. The VHE requires inversion symmetry breaking to occur, which takes place in the TMD monolayers but not in the bilayers. We show that a bilayer of 2H-MoS2 is an orbital Hall insulator that exhibits a sizeable orbital Hall effect in the absence of both spin and valley Hall effects. This phase can be characterized by an orbital Chern number that assumes the value CL=2 for the 2H-MoS2 bilayer and CL=1 for the monolayer, confirming the topological nature of these orbital-Hall insulator systems. Our results are based on density functional theory and low-energy effective model calculations and strongly suggest that bilayers of TMDs are highly suitable platforms for direct observation of the orbital Hall insulating phase in two-dimensional materials. Implications of our findings for attempts to observe the VHE in TMD bilayers are also discussed. © 2021 American Physical Society.

  • Doping-mediated stabilization of copper vacancies to promote thermoelectric properties of Cu2−xS

    Zhang Y., Xing C., Liu Y., Spadaro M.C., Wang X., Li M., Xiao K., Zhang T., Guardia P., Lim K.H., Moghaddam A.O., Llorca J., Arbiol J., Ibáñez M., Cabot A. Nano Energy; 85 (105991) 2021. 10.1016/j.nanoen.2021.105991. IF: 16.602

    Advanced Electron Nanoscopy

    Copper chalcogenides are outstanding thermoelectric materials for applications in the medium-high temperature range. Among different chalcogenides, while Cu2−xSe is characterized by higher thermoelectric figures of merit, Cu2−xS provides advantages in terms of low cost and element abundance. In the present work, we investigate the effect of different dopants to enhance the Cu2−xS performance and also its thermal stability. Among the tested options, Pb-doped Cu2−xS shows the highest improvement in stability against sulfur volatilization. Additionally, Pb incorporation allows tuning charge carrier concentration, which enables a significant improvement of the power factor. We demonstrate here that the introduction of an optimal additive amount of just 0.3% results in a threefold increase of the power factor in the middle-temperature range (500–800 K) and a record dimensionless thermoelectric figure of merit above 2 at 880 K. © 2021 Elsevier Ltd

  • Effect of the Annealing Atmosphere on Crystal Phase and Thermoelectric Properties of Copper Sulfide

    Li M., Liu Y., Zhang Y., Han X., Zhang T., Zuo Y., Xie C., Xiao K., Arbiol J., Llorca J., Ibáñez M., Liu J., Cabot A. ACS Nano; 15 (3): 4967 - 4978. 2021. 10.1021/acsnano.0c09866. IF: 14.588

    Advanced Electron Nanoscopy

    Cu2-xS has become one of the most promising thermoelectric materials for application in the middle-high temperature range. Its advantages include the abundance, low cost, and safety of its elements and a high performance at relatively elevated temperatures. However, stability issues limit its operation current and temperature, thus calling for the optimization of the material performance in the middle temperature range. Here, we present a synthetic protocol for large scale production of covellite CuS nanoparticles at ambient temperature and atmosphere, and using water as a solvent. The crystal phase and stoichiometry of the particles are afterward tuned through an annealing process at a moderate temperature under inert or reducing atmosphere. While annealing under argon results in Cu1.8S nanopowder with a rhombohedral crystal phase, annealing in an atmosphere containing hydrogen leads to tetragonal Cu1.96S. High temperature X-ray diffraction analysis shows the material annealed in argon to transform to the cubic phase at ca. 400 K, while the material annealed in the presence of hydrogen undergoes two phase transitions, first to hexagonal and then to the cubic structure. The annealing atmosphere, temperature, and time allow adjustment of the density of copper vacancies and thus tuning of the charge carrier concentration and material transport properties. In this direction, the material annealed under Ar is characterized by higher electrical conductivities but lower Seebeck coefficients than the material annealed in the presence of hydrogen. By optimizing the charge carrier concentration through the annealing time, Cu2-xS with record figures of merit in the middle temperature range, up to 1.41 at 710 K, is obtained. We finally demonstrate that this strategy, based on a low-cost and scalable solution synthesis process, is also suitable for the production of high performance Cu2-xS layers using high throughput and cost-effective printing technologies. ©

  • Effects of solar irradiation on thermally driven CO2 methanation using Ni/CeO2–based catalyst

    Golovanova V., Spadaro M.C., Arbiol J., Golovanov V., Rantala T.T., Andreu T., Morante J.R. Applied Catalysis B: Environmental; 291 (120038) 2021. 10.1016/j.apcatb.2021.120038. IF: 16.683

    Advanced Electron Nanoscopy

    Utilization of the renewable energy sources is one of the main challenges in the state-of-the-art technologies for CO2 recycling. Here we have taken advantage of the solar light harvesting in the thermocatalytic approach to carbon dioxide methanation. The large-surface-area Ni/CeO2 catalyst produced by a scalable low-cost method was characterized and tested in the dark and under solar light irradiation conditions. Light-assisted CO2 conversion experiments as well as in-situ DRIFT spectrometry, performed at different illumination intensities, have revealed a dual effect of the incident photons on the catalytic properties of the two-component Ni/CeO2 catalyst. On the one hand, absorbed photons induce a localized surface plasmon resonance in the Ni nanoparticles followed by dissipation of the heat to the oxide matrix. On the other hand, the illumination activates the photocatalytic properties of the CeO2 support, which leads to an increase in the concentration of the intermediates being precursor for methane production. Analysis of the methane production at different temperatures and illumination conditions has shown that the methanation reaction in our case is controlled by a photothermally-activated process. The used approach has allowed us to increase the reaction rate up to 2.4 times and consequently to decrease the power consumption by 20 % under solar illumination, thus replacing the conventional thermal activation of the reaction with a green energy source. © 2021 The Authors

  • Electrical tunability of terahertz nonlinearity in graphene

    Kovalev S., Hafez H.A., Tielrooij K.-J., Deinert J.-C., Ilyakov I., Awari N., Alcaraz D., Soundarapandian K., Saleta D., Germanskiy S., Chen M., Bawatna M., Green B., Koppens F.H.L., Mittendorff M., Bonn M., Gensch M., Turchinovich D. Science Advances; 7 (15, eabf9809) 2021. 10.1126/SCIADV.ABF9809. IF: 13.117

    Ultrafast Dynamics in Nanoscale Systems

    Graphene is conceivably the most nonlinear optoelectronic material we know. Its nonlinear optical coefficients in the terahertz frequency range surpass those of other materials by many orders of magnitude. Here, we show that the terahertz nonlinearity of graphene, both for ultrashort single-cycle and quasi-monochromatic multicycle input terahertz signals, can be efficiently controlled using electrical gating, with gating voltages as low as a few volts. For example, optimal electrical gating enhances the power conversion efficiency in terahertz third-harmonic generation in graphene by about two orders of magnitude. Our experimental results are in quantitative agreement with a physical model of the graphene nonlinearity, describing the time-dependent thermodynamic balance maintained within the electronic population of graphene during interaction with ultrafast electric fields. Our results can serve as a basis for straightforward and accurate design of devices and applications for efficient electronic signal processing in graphene at ultrahigh frequencies. © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).

  • Elucidating pore chemistry within metal-organic frameworksviasingle crystal X-ray diffraction; from fundamental understanding to application

    Albalad J., Sumby C.J., Maspoch D., Doonan C.J. CrystEngComm; 23 (11): 2185 - 2195. 2021. 10.1039/d1ce00067e. IF: 3.117

    Supramolecular NanoChemistry and Materials

    Metal-organic frameworks (MOFs) have made inroads in diverse chemical sectors due to the essentially limitless combination of building units and the ability to post-synthetically modify their pore chemistry at the molecular level. The crystalline nature of MOFs permits the use of single crystal X-ray diffraction (SCXRD) to obtain crystallographic snapshots of these transformations, providing invaluable information into the unorthodox chemistry that MOFs can potentially offer. This highlight article aims to provide the reader with the most recent milestones in the use of SCXRD as a vanguard technique to connect molecular-level pore engineering of MOFs with new application fields hitherto unexplored. © The Royal Society of Chemistry 2021.

  • 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., Genç A., Liu Y., Kleinhanns T., Lee S., Dirin D.N., Akkerman Q.A., Kovalenko M.V., Arbiol J., Ibáñez M. ACS Energy Letters; 6 (2): 581 - 587. 2021. 10.1021/acsenergylett.0c02448. IF: 19.003

    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. © 2021 American Chemical Society.

  • Exploring billion-atom-scale quantum materials using linear scaling quantum transport

    Garcia J.H. Nature Reviews Physics; 3 (6): 388. 2021. 10.1038/s42254-021-00318-1. IF: 0.000

    Theoretical and Computational Nanoscience

    [No abstract available]

  • Exploring the elastic and electronic properties of chromium molybdenum diboride alloys

    Dovale-Farelo V., Tavadze P., Verstraete M.J., Bautista-Hernández A., Romero A.H. Journal of Alloys and Compounds; 866 (158885) 2021. 10.1016/j.jallcom.2021.158885. IF: 4.650

    Theory and Simulation

    We perform first-principles calculations to study the structural, mechanical, thermal, electronic, and magnetic properties of Cr1−xMoxB2 for x = 0.25, 0.33, 0.50, 0.67 and 0.75. Based on structural search methods, we determine the ground-state structure for each concentration. The ternaries are either monoclinic (x = 0.25, 0.75) or trigonal (x = 0.33, 0.50, 0.67). The calculated mechanical properties reveal that the strength of Cr1−xMoxB2 is maximized for x = 0.50. Cr0.5Mo0.5B2 exhibits excellent mechanical properties (B = 298 GPa, Y = 558 GPa, G = 235 Gpa, ν = 0.19, Hv =27 GPa), surpassing those of β-MoB2 at a lower cost. All of these ternaries are hard alloys with Vickers hardness greater than 24 GPa. Chemical bonding analysis demonstrates that the strength of the new compounds is related to the alternating planar and buckled B-B layers, as well as the strong TM-B bonds. The enhanced strength of Cr0.5Mo0.5B2 is a consequence of the high density of strong interlayer Cr-Mo metallic bonds around the Fermi level. © 2021 Elsevier B.V.

  • Fast Label-Free Nanoscale Composition Mapping of Eukaryotic Cells Via Scanning Dielectric Force Volume Microscopy and Machine Learning

    Checa M., Millan-Solsona R., Mares A.G., Pujals S., Gomila G. Small Methods; 2021. 10.1002/smtd.202100279. IF: 12.130

    Advanced AFM Laboratory

    Mapping the biochemical composition of eukaryotic cells without the use of exogenous labels is a long-sought objective in cell biology. Recently, it has been shown that composition maps on dry single bacterial cells with nanoscale spatial resolution can be inferred from quantitative nanoscale dielectric constant maps obtained with the scanning dielectric microscope. Here, it is shown that this approach can also be applied to the much more challenging case of fixed and dry eukaryotic cells, which are highly heterogeneous and show micrometric topographic variations. More importantly, it is demonstrated that the main bottleneck of the technique (the long computation times required to extract the nanoscale dielectric constant maps) can be shortcut by using supervised neural networks, decreasing them from weeks to seconds in a wokstation computer. This easy-to-use data-driven approach opens the door for in situ and on-the-fly label free nanoscale composition mapping of eukaryotic cells with scanning dielectric microscopy. © 2021 The Authors. Small Methods published by Wiley-VCH GmbH

  • 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.

  • Functionalized carbon dots on TiO2 for perovskite photovoltaics and stable photoanodes for water splitting

    Ansón-Casaos A., Hernández-Ferrer J., Vallan L., Xie H., Lira-Cantú M., Benito A.M., Maser W.K. International Journal of Hydrogen Energy; 46 (22): 12180 - 12191. 2021. 10.1016/j.ijhydene.2020.03.077. IF: 4.939

    Nanostructured Materials for Photovoltaic Energy

    Various types of fluorescent carbon nanoparticles, often called carbon dots (CDs), are synthesized by different polycondensation methods: microwave irradiation, hydrothermal conditions or solution chemistry at ambient temperature with subsequent chemical functionalization. The CDs are deposited on TiO2 films to be probed as electron transport layers in perovskite photovoltaics and the anode for photoelectrochemical water splitting. Nitrogen CDs, which do not contain oxygen, lead to an increase of around 50 mV in the open circuit voltage of perovskite solar cells. All the CD types produce an improved photocurrent in water splitting, particularly CDs that are functionalized with thiol groups and butyl chains. It is demonstrated that the modified electrode is stable under continuous operation. Other electrochemical characteristics of the electrode, such as the voltammogram shape, onset potentials and open circuit potentials, remain nearly unchanged upon the deposition of CDs. Only the incident photon to current conversion efficiency improves clearly, extending the absorption range by around 20 nm towards longer wavelengths. This study provides new data about mechanisms and electrode arrangements for improving the performance of n-type semiconductors in photovoltaic cells and photoelectrochemical hydrogen production. © 2020 Hydrogen Energy Publications LLC

  • 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; 4 (2): 1467 - 1477. 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. All rights reserved.

  • Gold nanoparticles (AuNPs) impair LPS-driven immune responses by promoting a tolerogenic-like dendritic cell phenotype with altered endosomal structures

    Michelini S., Barbero F., Prinelli A., Steiner P., Weiss R., Verwanger T., Andosch A., Lütz-Meindl U., Puntes V.F., Drobne D., Duschl A., Horejs-Hoeck J. Nanoscale; 13 (16): 7648 - 7666. 2021. 10.1039/d0nr09153g. IF: 6.895

    Inorganic Nanoparticles

    Dendritic cells (DCs) shape immune responses by influencing T-cell activation. Thus, they are considered both an interesting model for studying nano-immune interactions and a promising target for nano-based biomedical applications. However, the accentuated ability of nanoparticles (NPs) to interact with biomolecules may have an impact on DC function that poses an unexpected risk of unbalanced immune reactions. Here, we investigated the potential effects of gold nanoparticles (AuNPs) on DC function and the consequences for effector and memory T-cell responses in the presence of the microbial inflammatory stimulus lipopolysaccharide (LPS). Overall, we found that, in the absence of LPS, none of the tested NPs induced a DC response. However, whereas 4-, 8-, and 11 nm AuNPs did not modulate LPS-dependent immune responses, 26 nm AuNPs shifted the phenotype of LPS-activated DCs toward a tolerogenic state, characterized by downregulation of CD86, IL-12 and IL-27, upregulation of ILT3, and induction of class E compartments. Moreover, this DC phenotype was less proficient in promoting Th1 activation and central memory T-cell proliferation. Taken together, these findings support the perception that AuNPs are safe under homeostatic conditions; however, particular care should be taken in patients experiencing a current infection or disorders of the immune system. © 2021 The Royal Society of Chemistry.

  • 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 on two-dimensional hexagonal BN, AlN, and GaN: Electronic, spin-orbit, and spin relaxation properties

    Zollner K., Cummings A.W., Roche S., Fabian J. Physical Review B; 103 (7, 075129) 2021. 10.1103/PhysRevB.103.075129. IF: 3.575

    Theoretical and Computational Nanoscience

    We investigate the electronic band structure of graphene on a series of two-dimensional hexagonal nitride insulators hXN, X=B, Al, and Ga, with first-principles calculations. A symmetry-based model Hamiltonian is employed to extract orbital parameters and spin-orbit coupling (SOC) from the low-energy Dirac bands of the proximitized graphene. While commensurate hBN induces a staggered potential of about 10 meV into the Dirac band structure, less lattice-matched hAlN and hGaN disrupt the Dirac point much less, giving a staggered gap below 100 μeV. Proximitized intrinsic SOC surprisingly does not increase much above the pristine graphene value of 12 μeV; it stays in the window of 1-16 μeV, depending strongly on stacking. However, Rashba SOC increases sharply when increasing the atomic number of the boron group, with calculated maximal values of 8, 15, and 65 μeV for B-, Al-, and Ga-based nitrides, respectively. The individual Rashba couplings also depend strongly on stacking, vanishing in symmetrically sandwiched structures, and can be tuned by a transverse electric field. The extracted spin-orbit parameters were used as input for spin transport simulations based on Chebyshev expansion of the time-evolution of the spin expectation values, yielding interesting predictions for the electron spin relaxation. Spin lifetime magnitudes and anisotropies depend strongly on the specific (hXN)/graphene/hXN system, and they can be efficiently tuned by an applied external electric field as well as the carrier density in the graphene layer. A particularly interesting case for experiments is graphene/hGaN, in which the giant Rashba coupling is predicted to induce spin lifetimes of 1-10 ns, short enough to dominate over other mechanisms, and lead to the same spin relaxation anisotropy as that observed in conventional semiconductor heterostructures: 50%, meaning that out-of-plane spins relax twice as fast as in-plane spins. © 2021 American Physical Society.

  • Graphene Oxide Nanosheets Interact and Interfere with SARS-CoV-2 Surface Proteins and Cell Receptors to Inhibit Infectivity

    Unal M.A., Bayrakdar F., Nazir H., Besbinar O., Gurcan C., Lozano N., Arellano L.M., Yalcin S., Panatli O., Celik D., Alkaya D., Agan A., Fusco L., Suzuk Yildiz S., Delogu L.G., Akcali K.C., Kostarelos K., Yilmazer A. Small; 2021. 10.1002/smll.202101483. IF: 11.459


    Nanotechnology can offer a number of options against coronavirus disease 2019 (COVID-19) acting both extracellularly and intracellularly to the host cells. Here, the aim is to explore graphene oxide (GO), the most studied 2D nanomaterial in biomedical applications, as a nanoscale platform for interaction with SARS-CoV-2. Molecular docking analyses of GO sheets on interaction with three different structures: SARS-CoV-2 viral spike (open state – 6VYB or closed state – 6VXX), ACE2 (1R42), and the ACE2-bound spike complex (6M0J) are performed. GO shows high affinity for the surface of all three structures (6M0J, 6VYB and 6VXX). When binding affinities and involved bonding types are compared, GO interacts more strongly with the spike or ACE2, compared to 6M0J. Infection experiments using infectious viral particles from four different clades as classified by Global Initiative on Sharing all Influenza Data (GISAID), are performed for validation purposes. Thin, biological-grade GO nanoscale (few hundred nanometers in lateral dimension) sheets are able to significantly reduce copies for three different viral clades. This data has demonstrated that GO sheets have the capacity to interact with SARS-CoV-2 surface components and disrupt infectivity even in the presence of any mutations on the viral spike. GO nanosheets are proposed to be further explored as a nanoscale platform for development of antiviral strategies against COVID-19. © 2021 The Authors. Small published by Wiley-VCH GmbH

  • Graphene oxide prevents lateral amygdala dysfunctional synaptic plasticity and reverts long lasting anxiety behavior in rats

    Franceschi Biagioni A., Cellot G., Pati E., Lozano N., Ballesteros B., Casani R., Coimbra N.C., Kostarelos K., Ballerini L. Biomaterials; 271 (120749) 2021. 10.1016/j.biomaterials.2021.120749. IF: 10.317

    Nanomedicine | Electron Microscopy Unit

    Engineered small graphene oxide (s-GO) sheets were previously shown to reversibly down-regulate glutamatergic synapses in the hippocampus of juvenile rats, disclosing an unexpected translational potential of these nanomaterials to target selective synapses in vivo. Synapses are anatomical specializations acting in the Central Nervous System (CNS) as functional interfaces among neurons. Dynamic changes in synaptic function, named synaptic plasticity, are crucial to learning and memory. More recently, pathological mechanisms involving dysfunctional synaptic plasticity were implicated in several brain diseases, from dementia to anxiety disorders. Hyper-excitability of glutamatergic neurons in the lateral nucleus of the amygdala complex (LA) is substantially involved in the storage of aversive memory induced by stressful events enabling post-traumatic stress disorder (PTSD). Here we translated in PTSD animal model the ability of s-GO, when stereotaxically administered to hamper LA glutamatergic transmission and to prevent the behavioral response featured in long-term aversive memory. We propose that s-GO, by interference with glutamatergic plasticity, impair LA-dependent memory retrieval related to PTSD. © 2021 The Authors

  • 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; 15 (1): 1145 - 1154. 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 ∼1% using a moderate field strength of ∼30 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. © 2021 American Chemical Society. All rights reserved.

  • 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.

  • Hinge Spin Polarization in Magnetic Topological Insulators Revealed by Resistance Switch

    Perez-Piskunow P.M., Roche S. Physical Review Letters; 126 (16, 167701) 2021. 10.1103/PhysRevLett.126.167701. IF: 8.385

    Theoretical and Computational Nanoscience

    We report on the possibility of detecting hinge spin polarization in magnetic topological insulators by resistance measurements. By implementing a three-dimensional model of magnetic topological insulators into a multiterminal device with ferromagnetic contacts near the top surface, local spin features of the chiral edge modes are unveiled. We find local spin polarization at the hinges that inverts the sign between the top and bottom surfaces. At the opposite edge, the topological state with inverted spin polarization propagates in the reverse direction. A large resistance switch between forward and backward propagating states is obtained, driven by the matching between the spin polarized hinges and the ferromagnetic contacts. This feature is general to the ferromagnetic, antiferromagnetic, and canted antiferromagnetic phases, and enables the design of spin-sensitive devices, with the possibility of reversing the hinge spin polarization of the currents. © 2021 American Physical Society.

  • Hot carriers in graphene-fundamentals and applications

    Massicotte M., Soavi G., Principi A., Tielrooij K.-J. Nanoscale; 13 (18): 8376 - 8411. 2021. 10.1039/d0nr09166a. IF: 6.895

    Ultrafast Dynamics in Nanoscale Systems

    Hot charge carriers in graphene exhibit fascinating physical phenomena, whose understanding has improved greatly over the past decade. They have distinctly different physical properties compared to, for example, hot carriers in conventional metals. This is predominantly the result of graphene's linear energy-momentum dispersion, its phonon properties, its all-interface character, and the tunability of its carrier density down to very small values, and from electron- to hole-doping. Since a few years, we have witnessed an increasing interest in technological applications enabled by hot carriers in graphene. Of particular interest are optical and optoelectronic applications, where hot carriers are used to detect (photodetection), convert (nonlinear photonics), or emit (luminescence) light. Graphene-enabled systems in these application areas could find widespread use and have a disruptive impact, for example in the field of data communication, high-frequency electronics, and industrial quality control. The aim of this review is to provide an overview of the most relevant physics and working principles that are relevant for applications exploiting hot carriers in graphene. © 2021 The Royal Society of Chemistry.

  • Hybrid Metal-Phenol Nanoparticles with Polydopamine-like Coating for PET/SPECT/CT Imaging

    SuÃirez-GarcÃ-A S., Esposito T.V.F., Neufeld-Peters J., Bergamo M., Yang H., Saatchi K., Schaffer P., HÃfeli U.O., Ruiz-Molina D., RodrÃ-Guez-RodrÃ-Guez C., Novio F. ACS Applied Materials and Interfaces; 13 (9): 10705 - 10718. 2021. 10.1021/acsami.0c20612. IF: 8.758

    Nanostructured Functional Materials

    The validation of metal-phenolic nanoparticles (MPNs) in preclinical imaging studies represents a growing field of interest due to their versatility in forming predesigned structures with unique properties. Before MPNs can be used in medicine, their pharmacokinetics must be optimized so that accumulation in nontargeted organs is prevented and toxicity is minimized. Here, we report the fabrication of MPNs made of a coordination polymer core that combines In(III), Cu(II), and a mixture of the imidazole 1,4-bis(imidazole-1-ylmethyl)-benzene and the catechol 3,4-dihydroxycinnamic acid ligands. Furthermore, a phenolic-based coating was used as an anchoring platform to attach poly(ethylene glycol) (PEG). The resulting MPNs, with effective hydrodynamic diameters of around 120 nm, could be further derivatized with surface-embedded molecules, such as folic acid, to facilitate in vivo targeting and multifunctionality. The prepared MPNs were evaluated for in vitro plasma stability, cytotoxicity, and cell internalization and found to be biocompatible under physiological conditions. First, biomedical evaluations were then performed by intrinsically incorporating trace amounts of the radioactive metals 111In or 64Cu during the MPN synthesis directly into their polymeric matrix. The resulting particles, which had identical physicochemical properties to their nonradioactive counterparts, were used to perform in vivo single-photon emission computed tomography (SPECT) and positron emission tomography (PET) in tumor-bearing mice. The ability to incorporate multiple metals and radiometals into MPNs illustrates the diverse range of functional nanoparticles that can be prepared with this approach and broadens the scope of these nanoconstructs as multimodal preclinical imaging agents. ©

  • 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

    Thermal Properties of Nanoscale Materials

    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.

  • Influence of copper telluride nanodomains on the transport properties of n-type bismuth telluride

    Zhang Y., Xing C., Liu Y., Li M., Xiao K., Guardia P., Lee S., Han X., Ostovari Moghaddam A., Josep Roa J., Arbiol J., Ibáñez M., Pan K., Prato M., Xie Y., Cabot A. Chemical Engineering Journal; 418 (129374) 2021. 10.1016/j.cej.2021.129374. IF: 10.652

    Advanced Electron Nanoscopy

    The high processing cost, poor mechanical properties and moderate performance of Bi2Te3–based alloys used in thermoelectric devices limit the cost-effectiveness of this energy conversion technology. Towards solving these current challenges, in the present work, we detail a low temperature solution-based approach to produce Bi2Te3-Cu2-xTe nanocomposites with improved thermoelectric performance. Our approach consists in combining proper ratios of colloidal nanoparticles and to consolidate the resulting mixture into nanocomposites using a hot press. The transport properties of the nanocomposites are characterized and compared with those of pure Bi2Te3 nanomaterials obtained following the same procedure. In contrast with most previous works, the presence of Cu2-xTe nanodomains does not result in a significant reduction of the lattice thermal conductivity of the reference Bi2Te3 nanomaterial, which is already very low. However, the introduction of Cu2-xTe yields a nearly threefold increase of the power factor associated to a simultaneous increase of the Seebeck coefficient and electrical conductivity at temperatures above 400 K. Taking into account the band alignment of the two materials, we rationalize this increase by considering that Cu2-xTe nanostructures, with a relatively low electron affinity, are able to inject electrons into Bi2Te3, enhancing in this way its electrical conductivity. The simultaneous increase of the Seebeck coefficient is related to the energy filtering of charge carriers at energy barriers within Bi2Te3 domains associated with the accumulation of electrons in regions nearby a Cu2-xTe/Bi2Te3 heterojunction. Overall, with the incorporation of a proper amount of Cu2-xTe nanoparticles, we demonstrate a 250% improvement of the thermoelectric figure of merit of Bi2Te3. © 2021 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; 10 (2): 1319 - 1327. 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.

  • Integrated Devices for Non-Invasive Diagnostics

    Ates H.C., Brunauer A., von Stetten F., Urban G.A., Güder F., Merkoçi A., Früh S.M., Dincer C. Advanced Functional Materials; 31 (15, 2010388) 2021. 10.1002/adfm.202010388. IF: 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.

  • Interaction of nanoparticles with endotoxin Importance in nanosafety testing and exploitation for endotoxin binding

    Mangini M., Verde A., Boraschi D., Puntes V.F., Italiani P., De Luca A.C. Nanotoxicology; 15 (4): 558 - 576. 2021. 10.1080/17435390.2021.1898690. IF: 4.925

    Inorganic Nanoparticles

    The interaction between engineered nanoparticles and the bacterial lipopolysaccharide, or endotoxin, is an event that warrants attention. Endotoxin is one of the most potent stimulators of inflammation and immune reactions in human beings, and is a very common contaminant in research labs. In nanotoxicology and nanomedicine, the presence of endotoxin on the nanoparticle surface affects their biological properties leading to misinterpretation of results. This review discusses the importance of detecting the endotoxin contamination on nanoparticles, focusing on the current method of endotoxin detection and their suitability for nanoparticulate materials. Conversely, the capacity of nanoparticles to bind endotoxin can be enhanced by functionalization with endotoxin-capturing molecules, opening the way to the development of novel endotoxin detection assays. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

  • 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; 903: 1 - 69. 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)

  • Localized electronic vacancy level and its effect on the properties of doped manganites

    Juan D., Pruneda M., Ferrari V. Scientific Reports; 11 (1, 6706) 2021. 10.1038/s41598-021-85945-5. IF: 3.998

    Theory and Simulation

    Oxygen vacancies are common to most metal oxides and usually play a crucial role in determining the properties of the host material. In this work, we perform ab initio calculations to study the influence of vacancies in doped manganites La (1 - x)Sr xMnO 3, varying both the vacancy concentration and the chemical composition within the ferromagnetic-metallic range (0.2<x<0.5). We find that oxygen vacancies give rise to a localized electronic level and analyse the effects that the possible occupation of this defect state can have on the physical properties of the host. In particular, we observe a substantial reduction of the exchange energy that favors spin-flipped configurations (local antiferromagnetism), which correlate with the weakening of the double-exchange interaction, the deterioration of the metallicity, and the degradation of ferromagnetism in reduced samples. In agreement with previous studies, vacancies give rise to a lattice expansion when the defect level is unoccupied. However, our calculations suggest that under low Sr concentrations the defect level can be populated, which conversely results in a local reduction of the lattice parameter. Although the exact energy position of this defect level is sensitive to the details of the electronic interactions, we argue that it is not far from the Fermi energy for optimally doped manganites (x∼1/3), and thus its occupation could be tuned by controlling the number of available electrons, either with chemical doping or gating. Our results could have important implications for engineering the electronic properties of thin films in oxide compounds. © 2021, The Author(s).

  • Long-lived charge separation following pump-wavelength–dependent ultrafast charge transfer in graphene/WS2 heterostructures

    Fu S., du Fossé I., Jia X., Xu J., Yu X., Zhang H., Zheng W., Krasel S., Chen Z., Wang Z.M., Tielrooij K.-J., Bonn M., Houtepen A.J., Wang H.I. Science Advances; 7 (9, eabd9061) 2021. 10.1126/sciadv.abd9061. IF: 13.117

    Ultrafast Dynamics in Nanoscale Systems

    Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo-thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the performance of optoelectronic devices, in particular photodetection. Copyright © 2021 The Authors, some rights reserved;

  • Macroscopic Ultralight Aerogel Monoliths of Imine-based Covalent Organic Frameworks

    Martín-Illán J.Á., Rodríguez-San-Miguel D., Castillo O., Beobide G., Perez-Carvajal J., Imaz I., Maspoch D., Zamora F. Angewandte Chemie - International Edition; 60 (25): 13969 - 13977. 2021. 10.1002/anie.202100881. IF: 12.959

    Supramolecular NanoChemistry and Materials

    The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three-step method to produce COF aerogels, based on sol-gel transition, solvent-exchange, and supercritical CO2 drying, in which 2D imine-based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm−3), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate strain (<25–35 %) but become plastic under greater strain. Moreover, these COF aerogels maintain the micro- and meso-porosity of their constituent COFs, and show excellent absorption capacity (e.g. toluene uptake: 32 g g−1), with high removal efficiency (ca. 99 %). The same three-step method can be used to create functional composites of these COF aerogels with nanomaterials. © 2021 Wiley-VCH GmbH

  • Mesoporous silica coated CeO2nanozymes with combined lipid-lowering and antioxidant activity induce long-term improvement of the metabolic profile in obese Zucker rats

    Parra-Robert M., Zeng M., Shu Y., Fernández-Varo G., Perramón M., Desai D., Chen J., Guo D., Zhang X., Morales-Ruiz M., Rosenholm J.M., Jiménez W., Puntes V., Casals E., Casals G. Nanoscale; 13 (18): 8452 - 8466. 2021. 10.1039/d1nr00790d. IF: 6.895

    Inorganic Nanoparticles

    Obesity is one of the most important public health problems that is associated with an array of metabolic disorders linked to cardiovascular disease, stroke, type 2 diabetes, and cancer. A sustained therapeutic approach to stop the escalating prevalence of obesity and its associated metabolic comorbidities remains elusive. Herein, we developed a novel nanocomposite based on mesoporous silica coated cerium oxide (CeO2) nanozymes that reduce the circulating levels of fatty acids and remarkably improve the metabolic phenotype in a model of obese Zucker rats five weeks after its administration. Lipidomic and gene expression analyses showed an amelioration of the hyperlipidemia and of the hepatic and adipose metabolic dysregulations, which was associated with a down-regulation of the hepatic PI3K/mTOR/AKT pathway and a reduction of the M1 proinflammatory cytokine TNF-a. In addition, the coating of the CeO2 maximized its cell antioxidant protective effects and minimized non-hepatic biodistribution. The one-pot synthesis method for the nanocomposite fabrication is implemented entirely in aqueous solution, room temperature and open atmosphere conditions, favoring scalability and offering a safe and translatable lipid-lowering and antioxidant nanomedicine to treat metabolic comorbidities associated with obesity. This approach may be further applied to address other metabolic disorders related to hyperlipidemia, low-grade inflammation and oxidative stress. © 2021 The Royal Society of Chemistry.

  • Metallic Diluted Dimerization in VO2 Tweeds

    Sandiumenge F., Rodríguez L., Pruneda M., Magén C., Santiso J., Catalan G. Advanced Materials; 33 (9, 2004374) 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; 17 (15, 2006012) 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

  • Millimeter-Shaped Metal-Organic Framework/Inorganic Nanoparticle Composite as a New Adsorbent for Home Water-Purification Filters

    Boix G., Han X., Imaz I., Maspoch D. ACS Applied Materials and Interfaces; 13 (15): 17835 - 17843. 2021. 10.1021/acsami.1c02940. IF: 8.758

    Supramolecular NanoChemistry and Materials

    Heavy-metal contamination of water is a global problem with an especially severe impact in countries with old or poorly maintained infrastructure for potable water. An increasingly popular solution for ensuring clean and safe drinking water in homes is the use of adsorption-based water filters, given their affordability, efficacy, and simplicity. Herein, we report the preparation and functional validation of a new adsorbent for home water filters, based on our metal-organic framework (MOF) composite containing UiO-66 and cerium(IV) oxide (CeO2) nanoparticles. We began by preparing CeO2@UiO-66 microbeads and then encapsulating them in porous polyethersulfone (PES) granules to obtain millimeter-scale CeO2@UiO-66@PES granules. Next, we validated these granules as an adsorbent for the removal of metals from water by substituting them for the standard adsorbent (ion-exchange resin spheres) inside a commercially available water pitcher from Brita. We assessed their performance according to the American National Standards Institute (ANSI) guideline 53-2019, "Drinking Water Treatment Units - Health Effects Standard". Remarkably, a pitcher loaded with a combination of our CeO2@UiO-66@PES granules and activated carbon at standard ratios met the target reduction thresholds set by NSF/ANSI 53-2019 for all the metals tested: As(III), As(V), Cd(II), Cr(III), Cr(VI), Cu(II), Hg(II), and Pb(II). Throughout the test, the modified pitcher proved to be robust and stable. We are confident that our findings will bring MOF-based adsorbents one step closer to real-world use. © 2021 American Chemical Society.

  • Multiscale modeling strategy to solve fullerene formation mystery

    Popov A.M., Lebedeva I.V., Vyrko S.A., Poklonski N.A. Fullerenes Nanotubes and Carbon Nanostructures; 2021. 10.1080/1536383X.2021.1900124. IF: 1.648

    Theory and Simulation

    Since fullerene formation occurs under conditions where direct observation of atomic-scale reactions is not possible, modeling is the only way to reveal atomistic mechanisms which can lead to selection of abundant fullerene isomers (like C60-Ih). In the present paper we review the results obtained for different atomistic mechanisms by various modeling techniques. Although it seems that atomic-scale processes related to odd fullerenes (such as growth by consecutive insertions of single carbon atoms and rearrangements of the sp2 structure promoted by extra sp atoms) provide the main contribution to selection of abundant isomers, at the moment there is no conclusive evidence in favor of any particular atomistic mechanism. Thus, the following multiscale modeling strategy to solve the mystery of the high yield of abundant fullerene isomers is suggested. On the one hand, sets of reactions between fullerene isomers can be described using theoretical graph techniques. On the other hand, reaction schemes can be revealed by classical molecular dynamics simulations with subsequent refinement of the activation barriers by ab initio calculations. Based on the reaction sets with the reaction probabilities derived in this way, the different atomistic mechanisms of abundant fullerene isomer selection can be compared using kinetic models. © 2021 Taylor & Francis Group, LLC.

  • 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

  • Nanotechnology Approaches in Chronic Wound Healing

    Blanco-Fernandez B., Castaño O., Mateos-Timoneda M.A., Engel E., Pérez-Amodio S. Advances in Wound Care; 10 (5): 234 - 256. 2021. 10.1089/wound.2019.1094.

    Significance: The incidence of chronic wounds is increasing due to our aging population and the augment of people afflicted with diabetes. With the extended knowledge on the biological mechanisms underlying these diseases, there is a novel influx of medical technologies into the conventional wound care market. Recent Advances: Several nanotechnologies have been developed demonstrating unique characteristics that address specific problems related to wound repair mechanisms. In this review, we focus on the most recently developed nanotechnology-based therapeutic agents and evaluate the efficacy of each treatment in in vivo diabetic models of chronic wound healing. Critical Issues: Despite the development of potential biomaterials and nanotechnology-based applications for wound healing, this scientific knowledge is not translated into an increase of commercially available wound healing products containing nanomaterials. Future Directions: Further studies are critical to provide insights into how scientific evidences from nanotechnology-based therapies can be applied in the clinical setting. © 2021 by Mary Ann Liebert, Inc., publishers.

  • 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


    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

  • Near-Field Imaging of Magnetic Complex Mode Volume

    Caselli N., Wu T., Arregui G., Granchi N., Intonti F., Lalanne P., Gurioli M. ACS Photonics; 2021. 10.1021/acsphotonics.0c01943. IF: 6.864

    Phononic and Photonic Nanostructures

    The non-Hermitian nature of confined photonic modes is described by the electric complex modal volume, VE, which represents a key parameter that leads to counterintuitive effects, such as negative modal contribution to the local density of states and non-Lorentzian lineshapes. Here, we address the magnetic counterpart of VE by means of near-field perturbation experiments in a photonic crystal slab cavity. We study the relevant role played by the imaginary part of the magnetic modal volume, VH, which can increase the quality factor of the confined modes by means of a local external magnetic perturbation. We show how a mapping of the spatial distribution of both the real and imaginary parts of VH can be inferred by near-field experiments employing Al-covered near-field tips. Our findings deepen the role of the magnetic component of light and could open a new route in employing metamaterials, magnetic quantum emitters, and topological photonics. ©

  • 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.

  • Novel Graphene Electrode for Retinal Implants: An in vivo Biocompatibility Study

    Nguyen D., Valet M., Dégardin J., Boucherit L., Illa X., de la Cruz J., del Corro E., Bousquet J., Garrido J.A., Hébert C., Picaud S. Frontiers in Neuroscience; 15 (615256) 2021. 10.3389/fnins.2021.615256. IF: 3.707

    Advanced Electronic Materials and Devices

    Evaluating biocompatibility is a core essential step to introducing a new material as a candidate for brain-machine interfaces. Foreign body reactions often result in glial scars that can impede the performance of the interface. Having a high conductivity and large electrochemical window, graphene is a candidate material for electrical stimulation with retinal prosthesis. In this study, non-functional devices consisting of chemical vapor deposition (CVD) graphene embedded onto polyimide/SU-8 substrates were fabricated for a biocompatibility study. The devices were implanted beneath the retina of blind P23H rats. Implants were monitored by optical coherence tomography (OCT) and eye fundus which indicated a high stability in vivo up to 3 months before histology studies were done. Microglial reconstruction through confocal imaging illustrates that the presence of graphene on polyimide reduced the number of microglial cells in the retina compared to polyimide alone, thereby indicating a high biocompatibility. This study highlights an interesting approach to assess material biocompatibility in a tissue model of central nervous system, the retina, which is easily accessed optically and surgically. © Copyright © 2021 Nguyen, Valet, Dégardin, Boucherit, Illa, de la Cruz, del Corro, Bousquet, Garrido, Hébert and Picaud.

  • Optical Signatures of Defect Centers in Transition Metal Dichalcogenide Monolayers

    de Melo P.M.M.C., Zanolli Z., Verstraete M.J. Advanced Quantum Technologies; 4 (3, 2000118) 2021. 10.1002/qute.202000118. IF: 0.000

    Theory and Simulation

    Even the best quality 2D materials have non-negligible concentrations of vacancies and impurities. It is critical to understand and quantify how defects change intrinsic properties, and use this knowledge to generate functionality. This challenge can be addressed by employing many-body perturbation theory to obtain the optical absorption spectra of defected transition metal dichalcogenides. Herein metal vacancies, which are largely unreported, show a larger set of polarized excitons than chalcogenide vacancies, introducing localized excitons in the sub-optical-gap region, whose wave functions and spectra make them good candidates as quantum emitters. Despite the strong interaction with substitutional defects, the spin texture and pristine exciton energies are preserved, enabling grafting and patterning in optical detectors, as the full optical-gap region remains available. A redistribution of excitonic weight between the A and B excitons is visible in both cases and may allow the quantification of the defect concentration. This work establishes excitonic signatures to characterize defects in 2D materials and highlights vacancies as qubit candidates for quantum computing. © 2021 The Authors. Advanced Quantum Technologies published by Wiley-VCH GmbH

  • 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.

  • Optimizing the Photothermoelectric Effect in Graphene

    Antidormi A., Cummings A.W. Physical Review Applied; 15 (5, 054049) 2021. 10.1103/PhysRevApplied.15.054049. IF: 4.194

    Theoretical and Computational Nanoscience

    Among its many uses, graphene shows significant promise for optical and optoelectronic applications. In particular, devices based on the photothermoelectric effect (PTE) in graphene can offer a strong and fast photoresponse with a high signal-to-noise ratio while consuming minimal power. In this work, we discuss how to optimize the performance of graphene PTE photodetectors by tuning the light confinement, device geometry, and material quality. This study should prove useful for the design of devices using the PTE in graphene, with applications including optical sensing, data communications, multigas sensing, and others. © 2021 American Physical Society.

  • Optomechanical crystals for spatial sensing of submicron sized particles

    Navarro-Urrios D., Kang E., Xiao P., Colombano M.F., Arregui G., Graczykowski B., Capuj N.E., Sledzinska M., Sotomayor-Torres C.M., Fytas G. Scientific Reports; 11 (1, 7829) 2021. 10.1038/s41598-021-87558-4. IF: 3.998

    Phononic and Photonic Nanostructures

    Optomechanical crystal cavities (OMC) have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, bacteria and viruses. In this work we demonstrate the working principle of OMCs operating under ambient conditions as a sensor of submicrometer particles by optically monitoring the frequency shift of thermally activated mechanical modes. The resonator has been specifically designed so that the cavity region supports a particular family of low modal-volume mechanical modes, commonly known as -pinch modes-. These involve the oscillation of only a couple of adjacent cavity cells that are relatively insensitive to perturbations in other parts of the resonator. The eigenfrequency of these modes decreases as the deformation is localized closer to the centre of the resonator. Thus, by identifying specific modes that undergo a frequency shift that amply exceeds the mechanical linewidth, it is possible to infer if there are particles deposited on the resonator, how many are there and their approximate position within the cavity region. OMCs have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, viruses and bacteria. © 2021, The Author(s).

  • Origin of large negative electrocaloric effect in antiferroelectric PbZr O3

    Vales-Castro P., Faye R., Vellvehi M., Nouchokgwe Y., Perpiñà X., Caicedo J.M., Jordà X., Roleder K., Kajewski D., Perez-Tomas A., Defay E., Catalan G. Physical Review B; 103 (5, 054112) 2021. 10.1103/PhysRevB.103.054112. IF: 3.575

    Oxide Nanophysics | Nanomaterials Growth Unit | Advanced Electronic Materials and Devices

    We have studied the electrocaloric response of the archetypal antiferroelectric PbZrO3 as a function of voltage and temperature in the vicinity of its antiferroelectric-paraelectric phase transition. Large electrocaloric effects of opposite signs, ranging from an electrocooling of -3.5 K to an electroheating of +5.5K, were directly measured with an infrared camera. We show by calorimetric and electromechanical measurements that the large negative electrocaloric effect comes from an endothermic antiferroelectric-ferroelectric switching, in contrast to dipole destabilization of the antiparallel lattice, previously proposed as an explanation for the negative electrocaloric effect of antiferroelectrics. © 2021 American Physical Society.

  • Paper-based electrophoretic bioassay: Biosensing in whole blood operating via smartphone

    Merkoçi A., Sena-Torralba A., Alvarez-Diduk R., Parolo C., Torné-Morató H., Müller A. Analytical Chemistry; 93 (6): 3112 - 3121. 2021. 10.1021/acs.analchem.0c04330. IF: 6.785

    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 paperbased electrophoretic bioassay (PEB), that combines the key characteristics of a lateral flow assay (LFA) with the sample treatment capabilities of electrophoresis is developed. In particular, the ability of PEB to separate different types of particles and to detect human antibodies in untreated spiked whole blood is demonstrated. Finally, to make the platform suitable for PoC, PEB is coupled with a smartphone that controls the electrophoresis and reads the optical signal generated. It is believed that the PEB platform represents a much-needed solution for the detection of low target concentrations in complex media, solving one of the major limitations of LFA and opening opportunities for point-of-care sensors. © 2021 American Chemical Society.

  • Phase formation and thermoelectric properties of Zn1+xSb binary system

    OSTOVARI MOGHADDAM A., TROFIMOV E., ZHANG T., ARBIOL J., CABOT A. Transactions of Nonferrous Metals Society of China (English Edition); 31 (3): 753 - 763. 2021. 10.1016/S1003-6326(21)65536-X. IF: 2.615

    Advanced Electron Nanoscopy

    The phase formation and thermoelectric (TE) properties in the central region of the Zn−Sb phase diagram were analyzed through synthesizing a series of Zn1+xSb (x=0, 0.05, 0.1, 0.15, 0.25, 0.3) materials by reacting Zn and Sb powders below the solidus line of the Zn−Sb binary phase diagram followed by furnace cooling. In this process, the nonstoichiometric powder blend crystallized in a combination of ZnSb and β-Zn4Sb3 phases. Then, the materials were ground and hot pressed to form dense ZnSb/β-Zn4Sb3 composites. No traces of Sb and Zn elements or other phases were revealed by X-ray diffraction, high resolution transmission electron microscopy and electron energy loss spectroscopy analyses. The thermoelectric properties of all materials could be rationalized as a combination of the thermoelectric behavior of ZnSb and β-Zn4Sb3 phases, which were dominated by the main phase in each sample. Zn1.3Sb composite exhibited the best thermoelectric performance. It was also found that Ge doping substantially increased the Seebeck coefficient of Zn1.3Sb and led to significantly higher power factor, up to 1.51 mW·m−1·K−2 at 540 K. Overall, an exceptional and stable TE figure of merit (ZT) of 1.17 at 650 K was obtained for Zn1.28Ge0.02Sb. © 2021 The Nonferrous Metals Society of China

  • Photodehydrogenation of ethanol over cu2o/tio2 heterostructures

    Xing C., Zhang Y., Liu Y., Wang X., Li J., Martínez-Alanis P.R., Spadaro M.C., Guardia P., Arbiol J., Llorca J., Cabot A. Nanomaterials; 11 (6, 1399) 2021. 10.3390/nano11061399. IF: 4.324

    Advanced Electron Nanoscopy

    The photodehydrogenation of ethanol is a sustainable and potentially cost-effective strategy to produce hydrogen and acetaldehyde from renewable resources. The optimization of this process requires the use of highly active, stable and selective photocatalytic materials based on abundant elements and the proper adjustment of the reaction conditions, including temperature. In this work, Cu2O-TiO2 type-II heterojunctions with different Cu2O amounts are obtained by a one-pot hydrothermal method. The structural and chemical properties of the produced materials and their activity toward ethanol photodehydrogenation under UV and visible light illumination are evaluated. The Cu2O-TiO2 photocatalysts exhibit a high selectivity toward acetaldehyde production and up to tenfold higher hydrogen evolution rates compared to bare TiO2 . We further discern here the influence of temperature and visible light absorption on the photocatalytic performance. Our results point toward the combination of energy sources in thermo-photocatalytic reactors as an efficient strategy for solar energy conversion. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Plasmonic Biosensors for Single-Molecule Biomedical Analysis

    Mauriz E., Lechuga L.M. Biosensors; 11 (4) 2021. 10.3390/bios11040123. IF: 3.240

    NanoBiosensors and Bioanalytical Applications

    The rapid spread of epidemic diseases (i.e., coronavirus disease 2019 (COVID-19)) has contributed to focus global attention on the diagnosis of medical conditions by ultrasensitive detection methods. To overcome this challenge, increasing efforts have been driven towards the development of single-molecule analytical platforms. In this context, recent progress in plasmonic biosensing has enabled the design of novel detection strategies capable of targeting individual molecules while evaluating their binding affinity and biological interactions. This review compiles the latest advances in plasmonic technologies for monitoring clinically relevant biomarkers at the single-molecule level. Functional applications are discussed according to plasmonic sensing modes based on either nanoapertures or nanoparticle approaches. A special focus was devoted to new analytical developments involving a wide variety of analytes (e.g., proteins, living cells, nucleic acids and viruses). The utility of plasmonic-based single-molecule analysis for personalized medicine, considering technological limitations and future prospects, is also overviewed.

  • Polymeric Composite Dressings Containing Calcium-Releasing Nanoparticles Accelerate Wound Healing in Diabetic Mice

    Perez-Amodio S., Rubio N., Vila O.F., Navarro-Requena C., Castaño O., Sanchez-Ferrero A., Marti-Munoz J., Alsina-Giber M., Blanco J., Engel E. Advances in Wound Care; 10 (6): 301 - 316. 2021. 10.1089/wound.2020.1206.

    Objective: Wound healing is a complex process that involves the interaction between different cell types and bioactive factors. Impaired wound healing is characterized by a loss in synchronization of these interactions, resulting in nonhealing chronic wounds. Chronic wounds are a socioeconomic burden, one of the most prominent clinical manifestations of diabetes, however, they lack satisfactory treatment options. The objective of this study was to develop polymeric composites that deliver ions having wound healing properties and evaluate its performance using a pressure ulcer model in diabetic mice. Approach: To develop a polymeric composite wound dressing containing ion-releasing nanoparticles for chronic wound healing. This composite was chemically and physically characterized and evaluated using a pressure ulcer wound model in diabetic (db/db) mice to explore their potential as novel wound dressing. Results: This dressing exhibits a controlled ion release and a good in vitro bioactivity. The polymeric composite dressing treatment stimulates angiogenesis, collagen synthesis, granulation tissue formation, and accelerates wound closure of ischemic wounds created in diabetic mice. In addition, the performance of the newly designed composite is remarkably better than a commercially available dressing frequently used for the treatment of low-exuding chronic wounds. Innovation: The developed nanoplatforms are cell- and growth factor free and control the host microenvironment resulting in enhanced wound healing. These nanoplatforms are available by cost-effective synthesis with a defined composition, offering an additional advantage in potential clinical application. Conclusion: Based on the obtained results, these polymeric composites offer an optimum approach for chronic wound healing without adding cells or external biological factors. © 2021 Mary Ann Liebert Inc.. All rights reserved.

  • Polyoxometalates (POMs): From electroactive clusters to energy materials

    Horn M.R., Singh A., Alomari S., Goberna-Ferrón S., Benages-Vilau R., Chodankar N., Motta N., Ostrikov K., Macleod J., Sonar P., Gomez-Romero P., Dubal D. Energy and Environmental Science; 14 (4): 1652 - 1700. 2021. 10.1039/d0ee03407j. IF: 30.289

    Novel Energy-Oriented Materials

    Polyoxometalates (POMs) represent a class of nanomaterials, which hold enormous promise for a range of energy-related applications. Their promise is owing to their "special"structure that gives POMs a truly unique ability to control redox reactions in energy conversion and storage. One such amazing capability is their large number of redox active sites that arises from the complex three-dimensional cluster of metal-oxide ions linked together by oxygen atoms. Here, a critical review on how POMs emerged from being molecular clusters for fundamental studies, to next-generation materials for energy applications is provided. We highlight how exploiting the versatility and activity of these molecules can lead to improved performance in energy devices such as supercapacitors and batteries, and in energy catalyst applications. The potential of POMs across numerous fields is systematically outlined by investigating structure-property-performance relationships and the determinant factors for energy systems. Finally, the challenges and opportunities for this class of materials with respect to addressing our pressing energy-related concerns are identified. This journal is © The Royal Society of Chemistry.

  • Preclinical studies conducted on nanozyme antioxidants: Shortcomings and challenges based on US FDA regulations

    Ghorbani M., Izadi Z., Jafari S., Casals E., Rezaei F., Aliabadi A., Moore A., Ansari A., Puntes V., Jaymand M., Derakhshankhah H. Nanomedicine; 16 (13): 1133 - 1151. 2021. 10.2217/nnm-2021-0030. IF: 4.300

    Inorganic Nanoparticles

    The wide prevalence of oxidative stress-induced diseases has led to a growing demand for antioxidant therapeutics worldwide. Nanozyme antioxidants are drawing enormous attention as practical alternatives for conventional antioxidants. The considerable body of research over the last decade and the promising results achieved signify the potential of nanozyme antioxidants to secure a place in the expanding market of antioxidant therapeutics. Nonetheless, there is no report on clinical trials for their further evaluation. Through analyzing in-depth selected papers which have conducted in vivo studies on nanozyme antioxidants, this review aims to pinpoint and discuss possible reasons impeding development of research toward clinical studies and to offer some practical solutions for future studies to bridge the gap between preclinical and clinical stages. "We did not experience these kinds of strange illnesses in the past." Everybody might have heard such a familiar sentence from their grandparents and asked themselves, why? The current paper aims to provide readers with one of the answers: "Oxidative stress", which happens when the body fails to neutralize damage caused by unstable molecules called free radicals. In this paper, the authors present the seriousness of oxidative stress-induced clinical conditions. They discuss one of the promising treatments, nanozyme antioxidants, these are mostly based on nano-sized materials with enzyme-like function, in other words, they can speed up chemical reactions. Despite significant results, nanozyme antioxidants have not been investigated in clinical studies. This paper intends to search for the main reasons for this and suggest possible solutions. © 2021 Future Medicine Ltd. © 2021 Future Medicine Ltd.. All rights reserved.

  • Principles, technologies, and applications of plasmonic biosensors

    Soler M., Lechuga L.M. Journal of Applied Physics; 129 (11, 111102) 2021. 10.1063/5.0042811. IF: 2.286

    NanoBiosensors and Bioanalytical Applications

    Plasmonic materials and phenomena have been widely studied and applied in multiple fields for a long time. One of the most promising applications is in the engineering of biosensor devices, offering label-free and real-time analysis of biomolecular interactions with excellent performances. In this tutorial, we provide a pedagogical review of the working principles of plasmonic biosensors, main fabrication methods, instrumentation, and general guidelines for their development. Special focus is placed on the biosensor performance characterization and assessment, as well as on the sensor surface biofunctionalization. In the end, we discuss the common procedure to develop and validate biosensors for relevant biomedical and environmental purposes and future perspectives in terms of boosting capabilities and sensor integration in point-of-care platforms. © 2021 Author(s).

  • 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.

  • Pursuing the diffraction limit with nano-led scanning transmission optical microscopy

    Moreno S., Canals J., Moro V., Franch N., Vilà A., Romano-Rodriguez A., Prades J.D., Bezshlyakh D.D., Waag A., Kluczyk-Korch K., der Maur M.A., Di Carlo A., Krieger S., Geleff S., Diéguez A. Sensors; 21 (10, 3305) 2021. 10.3390/s21103305. IF: 3.275

    Thermal Properties of Nanoscale Materials

    Recent research into miniaturized illumination sources has prompted the development of alternative microscopy techniques. Although they are still being explored, emerging nano-light-emitting-diode (nano-LED) technologies show promise in approaching the optical resolution limit in a more feasible manner. This work presents the exploration of their capabilities with two different prototypes. In the first version, a resolution of less than 1 µm was shown thanks to a prototype based on an optically downscaled LED using an LED scanning transmission optical microscopy (STOM) technique. This research demonstrates how this technique can be used to improve STOM images by oversampling the acquisition. The second STOM-based microscope was fabricated with a 200 nm GaN LED. This demonstrates the possibilities for the miniaturization of on-chip-based microscopes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Push-Pull Electronic Effects in Surface-Active Sites Enhance Electrocatalytic Oxygen Evolution on Transition Metal Oxides

    Garcés-Pineda F.A., Chuong Nguyën H., Blasco-Ahicart M., García-Tecedor M., de Fez Febré M., Tang P.-Y., Arbiol J., Giménez S., Galán-Mascarós J.R., López N. ChemSusChem; 14 (6): 1595 - 1601. 2021. 10.1002/cssc.202002782. IF: 7.962

    Advanced Electron Nanoscopy

    Sustainable electrocatalysis of the oxygen evolution reaction (OER) constitutes a major challenge for the realization of green fuels. Oxides based on Ni and Fe in alkaline media have been proposed to avoid using critical raw materials. However, their ill-defined structures under OER conditions make the identification of key descriptors difficult. Here, we have studied Fe−Ni−Zn spinel oxides, with a well-defined crystal structure, as a platform to obtain general understanding on the key contributions. The OER reaches maximum performance when: (i) Zn is present in the Spinel structure, (ii) very dense, equimolar 1 : 1 : 1 stoichiometry sites appear on the surface as they allow the formation of oxygen vacancies where Zn favors pushing the electronic density that is pulled by the octahedral Fe and tetrahedral Ni redox pair lowering the overpotential. Our work proves cooperative electronic effects on surface active sites as key to design optimum OER electrocatalysts. © 2021 Wiley-VCH GmbH

  • 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.

  • Reversing the Humidity Response of MoS2- And WS2-Based Sensors Using Transition-Metal Salts

    Xiao P., Mencarelli D., Chavez-Angel E., Joseph C.H., Cataldo A., Pierantoni L., Sotomayor Torres C.M., Sledzinska M. ACS Applied Materials and Interfaces; 2021. 10.1021/acsami.1c03691. IF: 8.758

    Phononic and Photonic Nanostructures

    Two-dimensional materials, such as transition-metal dichalcogenides (TMDs), are attractive candidates for sensing applications due to their high surface-to-volume ratio, chemically active edges, and good electrical properties. However, their electrical response to humidity is still under debate and experimental reports remain inconclusive. For instance, in different studies, the impedance of MoS2-based sensors has been found to either decrease or increase with increasing humidity, compromising the use of MoS2 for humidity sensing. In this work, we focus on understanding the interaction between water and TMDs. We fabricated and studied humidity sensors based on MoS2 and WS2 coated with copper chloride and silver nitrate. The devices exhibited high chemical stability and excellent humidity sensing performance in relative humidity between 4 and 80%, with response and recovery times of 2 and 40 s, respectively. We have systematically investigated the humidity response of the materials as a function of the type and amount of induced metal salt and observed the reverse action of sensing mechanisms. This phenomenon is explained based on a detailed structural analysis of the samples considering the Grotthuss mechanism in the presence of charge trapping, which was represented by an appropriate lumped-element model. Our findings open up a possibility to tune the electrical response in a facile manner and without compromising the high performance of the sensor. They offer an insight into the time-dependent performance and aging of the TMD-based sensing devices. © 2021 American Chemical Society.

  • 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

    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.

  • Room-temperature tunnel magnetoresistance across biomolecular tunnel junctions based on ferritin

    Karuppannan S.K., Pasula R.R., Herng T.S., Ding J., Chi X., Barco E.D., Roche S., Yu X., Yakovlev N., Lim S., Nijhuis C.A. JPhys Materials; 4 (3, 035003) 2021. 10.1088/2515-7639/abfa79. IF: 0.000

    Theoretical and Computational Nanoscience

    We report exceptionally large tunnel magnetoresistance (TMR) for biomolecular tunnel junctions based on ferritins immobilized between Ni and EGaIn electrodes. Ferritin stores iron in the form of ferrihydrite nanoparticles (NPs) and fulfills the following roles: (a) it dictates the tunnel barrier, (b) it magnetically decouples the NPs from the ferromagnetic (FM) electrode, (c) it stabilizes the NPs, and (d) it acts as a spin filter reducing the complexity of the tunnel junctions since only one FM electrode is required. The mechanism of charge transport is long-range tunneling which results in TMR of 60 ± 10% at 200 K and 25 ± 5% at room temperature. We propose a magnon-assisted transmission to explain the substantially larger TMR switching fields (up to 1 Tesla) than the characteristic coercive fields (a few Gauss) of ferritin ferrihydrite particles at T < 20 K. These results highlight the genuine potential of biomolecular tunnel junctions in designing functional nanoscale spintronic devices. © 2021 The Author(s). Published by IOP Publishing Ltd.

  • Self-organised stripe domains and elliptical skyrmion bubbles in ultra-thin epitaxial Au0.67Pt0.33/Co/W(110) films

    Camosi L., Garcia J.P., Fruchart O., Pizzini S., Locatelli A., Menteş T.O., Genuzio F., Shaw J.M., Nembach H.T., Vogel J. New Journal of Physics; 23 (1, 013020) 2021. 10.1088/1367-2630/abdbe0. IF: 3.593

    Physics and Engineering of Nanodevices

    We studied the symmetry of magnetic properties and the resulting magnetic textures in ultra-thin epitaxial Au0.67Pt0.33/Co/W(110), a model system exhibiting perpendicular magnetic anisotropy and interface Dzyaloshinskii-Moriya interaction (DMI). As a peculiar feature, the C2v crystal symmetry induced by the Co/W interface results in an additional uniaxial in-plane magnetic anisotropy in the cobalt layer. Photo-emission electron microscopy with magnetic sensitivity reveals the formation of self-organised magnetic stripe domains oriented parallel to the hard in-plane magnetisation axis. We attribute this behavior to the lower domain wall energy when oriented along this axis, where both the DMI and the in-plane magnetic anisotropy favor a Néel domain wall configuration. The anisotropic domain wall energy also leads to the formation of elliptical skyrmion bubbles under a weak out-of-plane magnetic field. © 2021 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft

  • Shedding plasma membrane vesicles induced by graphene oxide nanoflakes in brain cultured astrocytes

    Musto M., Parisse P., Pachetti M., Memo C., Di Mauro G., Ballesteros B., Lozano N., Kostarelos K., Casalis L., Ballerini L. Carbon; 176: 458 - 469. 2021. 10.1016/j.carbon.2021.01.142. IF: 8.821

    Nanomedicine | Electron Microscopy Unit

    Microvesicles (MVs) generated and released by astrocytes, the brain prevalent cells, crucially contribute to intercellular communication, representing key vectorized systems able to spread and actively transfer signaling molecules from astrocytes to neurons, ultimately modulating target cell functions. The increasing clinical relevance of these signaling systems requires a deeper understanding of MV features, currently limited by both their nanoscale dimensions and the low rate of their constituent release. Hence, to investigate the features of such glial signals, nanotechnology-based approaches and the applications of unconventional, cost-effective tools in generating MVs are needed. Here, small graphene oxide (s-GO) nanoflakes are used to boost MVs shedding from astrocytes in cultures and s-GO generated MVs are compared with those generated by a natural stimulant, namely ATP, by atomic force microscopy, light scattering, attenuated total reflection–fourier transform infra-red and ultraviolet resonance Raman spectroscopy. We also report the ability of both types of MVs, upon acute and transient exposure of patch clamped cultured neurons, to modulate basal synaptic transmission, inducing a stable increase in synaptic activity accompanied by changes in neuronal plasma membrane elastic features. © 2021 The Author(s)

  • 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.

  • Simulations of micro-sphere/shell 2D silica photonic crystals for radiative cooling

    Whitworth G.L., Jaramillo-Fernandez J., Pariente J.A., Garcia P.D., Blanco A., Lopez C., Sotomayor-Torres C.M. Optics Express; 29 (11): 16857 - 16866. 2021. 10.1364/OE.420989. IF: 3.669

    Phononic and Photonic Nanostructures

    Passive daytime radiative cooling has recently become an attractive approach to address the global energy demand associated with modern refrigeration technologies. One technique to increase the radiative cooling performance is to engineer the surface of a polar dielectric material to enhance its emittance atwavelengths in the atmospheric infrared transparency window (8-13 ìm) by outcoupling surface-phonon polaritons (SPhPs) into free-space. Here we present a theoretical investigation of new surface morphologies based upon self-assembled silica photonic crystals (PCs) using an in-house built rigorous coupled-wave analysis (RCWA) code. Simulations predict that silica micro-sphere PCs can reach up to 73 K below ambient temperature, when solar absorption and conductive/convective losses can be neglected. Micro-shell structures are studied to explore the direct outcoupling of the SPhP, resulting in near-unity emittance between 8 and 10 ìm. Additionally, the effect of material composition is explored by simulating soda-lime glass micro-shells, which, in turn, exhibit a temperature reduction of 61 K below ambient temperature. The RCWA code was compared to FTIR measurements of silica micro-spheres, self-assembled on microscope slides. © 2021 Optical Society of America.

  • 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

  • Spontaneous phase segregation of Sr2NiO3 and SrNi2O3 during SrNiO3 heteroepitaxy

    Wang L., Yang Z., Yin X., Taylor S.D., He X., Tang C.S., Bowden M.E., Zhao J., Wang J., Liu J., Perea D.E., Wangoh L., Wee A.T.S., Zhou H., Chambers S.A., Du Y. Science Advances; 7 (10, eabe2866) 2021. 10.1126/sciadv.abe2866. IF: 13.117

    Theory and Simulation

    Recent discovery of superconductivity in Nd0.8Sr0.2NiO2 motivates the synthesis of other nickelates for providing insights into the origin of high-temperature superconductivity. However, the synthesis of stoichiometric R1−xSrxNiO3 thin films over a range of x has proven challenging. Moreover, little is known about the structures and properties of the end member SrNiO3. Here, we show that spontaneous phase segregation occurs while depositing SrNiO3 thin films on perovskite oxide substrates by molecular beam epitaxy. Two coexisting oxygen-deficient Ruddlesden-Popper phases, Sr2NiO3 and SrNi2O3, are formed to balance the stoichiometry and stabilize the energetically preferred Ni2+ cation. Our study sheds light on an unusual oxide thin-film nucleation process driven by the instability in perovskite structured SrNiO3 and the tendency of transition metal cations to form their most stable valence (i.e., Ni2+ in this case). The resulting metastable reduced Ruddlesden-Popper structures offer a testbed for further studying emerging phenomena in nickel-based oxides. Copyright © 2021 The Authors, some rights reserved;

  • Steric Hindrance in Metal Coordination Drives the Separation of Pyridine Regioisomers Using Rhodium(II)-Based Metal–Organic Polyhedra

    Hernández-López L., Martínez-Esaín J., Carné-Sánchez A., Grancha T., Faraudo J., Maspoch D. Angewandte Chemie - International Edition; 60 (20): 11406 - 11413. 2021. 10.1002/anie.202100091. IF: 12.959

    Supramolecular NanoChemistry and Materials

    The physicochemical similarity of isomers makes their chemical separation through conventional techniques energy intensive. Herein, we report that, instead of using traditional encapsulation-driven processes, steric hindrance in metal coordination on the outer surface of RhII-based metal–organic polyhedra (Rh-MOPs) can be used to separate pyridine-based regioisomers via liquid–liquid extraction. Through molecular dynamics simulations and wet experiments, we discovered that the capacity of pyridines to coordinatively bind to Rh-MOPs is determined by the positions of the pyridine substituents relative to the pyridine nitrogen and is influenced by steric hindrance. Thus, we exploited the differential solubility of bound and non-bound pyridine regioisomers to engineer liquid–liquid self-sorting systems. As a proof of concept, we separated four different equimolecular mixtures of regioisomers, including a mixture of the industrially relevant compounds 2-chloropyridine and 3-chloropyridine, isolating highly pure compounds in all cases. © 2021 Wiley-VCH GmbH

  • Stochastic modulation evidences a transitory EGF-Ras-ERK MAPK activity induced by PRMT5

    Jurado M., Castaño Ó., Zorzano A. Computers in Biology and Medicine; 133 (104339) 2021. 10.1016/j.compbiomed.2021.104339.

    The extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway involves a three-step cascade of kinases that transduce signals and promote processes such as cell growth, development, and apoptosis. An aberrant response of this pathway is related to the proliferation of cell diseases and tumors. By using simulation modeling, we document that the protein arginine methyltransferase 5 (PRMT5) modulates the MAPK pathway and thus avoids an aberrant behavior. PRMT5 methylates the Raf kinase, reducing its catalytic activity and thereby, reducing the activation of ERK in time and amplitude. Two minimal computational models of the epidermal growth factor (EGF)-Ras-ERK MAPK pathway influenced by PRMT5 were proposed: a first model in which PRMT5 is activated by EGF and a second one in which PRMT5 is stimulated by the cascade response. The reported results show that PRMT5 reduces the time duration and the expression of the activated ERK in both cases, but only in the first model PRMT5 limits the EGF range that generates an ERK activation. Based on our data, we propose the protein PRMT5 as a regulatory factor to develop strategies to fight against an excessive activity of the MAPK pathway, which could be of use in chronic diseases and cancer. © 2021

  • 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

  • Stressor‐dependant changes in immune parameters in the terrestrial isopod crustacean, porcellio scaber: A focus on nanomaterials

    Mayall C., Dolar A., Kokalj A.J., Novak S., Razinger J., Barbero F., Puntes V., Drobne D. Nanomaterials; 11 (4, 934) 2021. 10.3390/nano11040934. IF: 4.324

    Inorganic Nanoparticles

    We compared the changes of selected immune parameters of Porcellio scaber to different stressors. The animals were either fed for two weeks with Au nanoparticles (NPs), CeO2 NPs, or Au ions or body‐injected with Au NPs, CeO2 NPs, or lipopolysaccharide endotoxin. Contrary to expec-tations, the feeding experiment showed that both NPs caused a significant increase in the total hae-mocyte count (THC). In contrast, the ion‐positive control resulted in a significantly decreased THC. Additionally, changes in phenoloxidase (PO)‐like activity, haemocyte viability, and nitric oxide (NO) levels seemed to depend on the stressor. Injection experiments also showed stressor‐depend-ant changes in measured parameters, such as CeO2 NPs and lipopolysaccharide endotoxin (LPS), caused more significant responses than Au NPs. These results show that feeding and injection of NPs caused an immune response and that the response differed significantly, depending on the exposure route. We did not expect the response to ingested NPs, due to the low exposure concentrations (100 μg/g dry weight food) and a firm gut epithelia, along with a lack of phagocytosis in the digestive system, which would theoretically prevent NPs from crossing the biological barrier. It remains a challenge for future research to reveal what the physiological and ecological significance is for the organism to sense and respond, via the immune system, to ingested foreign material. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • Superelasticity preservation in dissimilar joint of NiTi shape memory alloy to biomedical PtIr

    Shamsolhodaei A., Oliveira J.P., Panton B., Ballesteros B., Schell N., Zhou Y.N. Materialia; 16 (101090) 2021. 10.1016/j.mtla.2021.101090. IF: 0.000

    Electron Microscopy Unit

    Laser microwelding was used to join, for the first time, superelastic NiTi to biomedical PtIr which can be used in multicomponent biomedical devices. By process optimization, it was possible to control the formation of the B2 NiTiPt phase, with no intermetallic compounds being formed. The NiTiPt phase inside the fusion zone had a strong metallurgical bonding with the NiTi base material due to the smooth transition of its grain orientation towards 〈111〉 B2 NiTi. The major finding of the present work is the preservation of the NiTi superelastic response in the welded joint as evidenced by the load/unloading cycling up to 6% strain, significantly higher than typically required for biomedical applications. © 2021

  • Sustained effect of zero-valent iron nanoparticles under semi-continuous anaerobic digestion of sewage sludge: Evolution of nanoparticles and microbial community dynamics

    Barrena R., Vargas-García M.D.C., Capell G., Barańska M., Puntes V., Moral-Vico J., Sánchez A., Font X. Science of the Total Environment; 777 (145969) 2021. 10.1016/j.scitotenv.2021.145969. IF: 6.551

    Inorganic Nanoparticles

    The effects of adding zero-valent iron nanoparticles (nZVI) on the physicochemical, biological and biochemical responses of a semi-continuous anaerobic digestion of sewage sludge have been assessed. Two sets of consecutive experiments of 103 and 116 days, respectively, were carried out in triplicate. nZVI were magnetically retained in the reactors, and the effect of punctual doses (from 0.27 to 4.33 g L−1) over time was studied. Among the different parameters monitored, only methane content in the biogas was significantly higher when nZVI was added. However, this effect was progressively lost after the addition, and in 5–7 days, the methane content returned to initial values. The increase in the oxidation state of nanoparticles seems to be related to the loss of effect over time. Higher dose (4.33 g L−1) sustained positive effects for a longer time along with higher methane content, but this fact seems to be related to microbiome acclimation. Changes in microbial community structure could also play a role in the mechanisms involved in methane enhancement. In this sense, the microbial consortium analysis reported a shift in the balance among acetogenic eubacterial communities, and a marked increase in the relative abundance of members assigned to Methanothrix genus, recognized as acetoclastic species showing high affinity for acetate, which explain the rise in methane content in the biogas. This research demonstrates that biogas methane enrichment in semicontinuous anaerobic digesters can be achieved by using nZVI nanoparticles, thus increasing energy production or reducing costs of a later biogas upgrading process. © 2021 Elsevier B.V.

  • Synthesis of 2D Porous Crystalline Materials in Simulated Microgravity

    Contreras-Pereda N., Rodríguez-San-Miguel D., Franco C., Sevim S., Vale J.P., Solano E., Fong W.-K., Giudice A.D., Galantini L., Pfattner R., Pané S., Mayor T.S., Ruiz-Molina D., Puigmartí-Luis J. Advanced Materials; 2021. 10.1002/adma.202101777. IF: 27.398

    Nanostructured Functional Materials

    To date, crystallization studies conducted in space laboratories, which are prohibitively costly and unsuitable to most research laboratories, have shown the valuable effects of microgravity during crystal growth and morphogenesis. Herein, an easy and highly efficient method is shown to achieve space-like experimentation conditions on Earth employing custom-made microfluidic devices to fabricate 2D porous crystalline molecular frameworks. It is confirmed that experimentation under these simulated microgravity conditions has unprecedented effects on the orientation, compactness and crack-free generation of 2D porous crystalline molecular frameworks as well as in their integration and crystal morphogenesis. It is believed that this work will provide a new “playground” to chemists, physicists, and materials scientists that desire to process unprecedented 2D functional materials and devices. © 2021 Wiley-VCH GmbH

  • Synthesis of Polycarboxylate Rhodium(II) Metal–Organic Polyhedra (MOPs) and their use as Building Blocks for Highly Connected Metal–Organic Frameworks (MOFs)

    Grancha T., Carné-Sánchez A., Zarekarizi F., Hernández-López L., Albalad J., Khobotov A., Guillerm V., Morsali A., Juanhuix J., Gándara F., Imaz I., Maspoch D. Angewandte Chemie - International Edition; 60 (11): 5729 - 5733. 2021. 10.1002/anie.202013839. IF: 12.959

    Supramolecular NanoChemistry and Materials

    Use of preformed metal-organic polyhedra (MOPs) as supermolecular building blocks (SBBs) for the synthesis of metal-organic frameworks (MOFs) remains underexplored due to lack of robust functionalized MOPs. Herein we report the use of polycarboxylate cuboctahedral RhII-MOPs for constructing highly-connected MOFs. Cuboctahedral MOPs were functionalized with carboxylic acid groups on their 12 vertices or 24 edges through coordinative or covalent post-synthetic routes, respectively. We then used each isolated polycarboxylate RhII-MOP as 12-c cuboctahedral or 24-c rhombicuboctahedral SBBs that, upon linkage with metallic secondary building units (SBUs), afford bimetallic highly-connected MOFs. The assembly of a pre-synthesized 12-c SBB with a 4-c paddle-wheel SBU, and a 24-c SBB with a 3-c triangular CuII SBU gave rise to bimetallic MOFs having ftw (4,12)-c or rht (3,24)-c topologies, respectively. © 2020 Wiley-VCH GmbH

  • TB2J: A python package for computing magnetic interaction parameters

    He X., Helbig N., Verstraete M.J., Bousquet E. Computer Physics Communications; 264 (107938) 2021. 10.1016/j.cpc.2021.107938. IF: 3.627

    Theory and Simulation

    We present TB2J, a Python package for the automatic computation of magnetic interactions, including exchange and Dzyaloshinskii–Moriya, between atoms of magnetic crystals from the results of density functional calculations. The program is based on the Green's function method with the local rigid spin rotation treated as a perturbation. As input, the package uses the output of either Wannier90, which is interfaced with many density functional theory packages, or of codes based on localized orbitals. One of the main interests of the code is that it requires only one first-principles electronic structure calculation in the non-relativistic case (or three in the relativistic case) and from the primitive cell only to obtain the magnetic interactions up to long distances, instead of first-principles calculations of many different magnetic configurations and large supercells. The output of TB2J can be used directly for the adiabatic magnon band structure and spin dynamics calculations. A minimal user input is needed, which allows for easy integration into high-throughput workflows. Program summary: Program Title: TB2J CPC Library link to program files: https://doi.org/10.17632/dm45fcn69d.1 Developer's repository link: https://github.com/mailhexu/TB2J Code Ocean capsule: https://codeocean.com/capsule/6486145 Licensing provisions: BSD 2-clause Programming language: Python Nature of problem: TB2J is a package for the computing of parameters in the extended Heisenberg model of the magnetic interaction, including the isotropic exchange, anisotropic exchange and Dzyaloshinskii–Moriya interactions from first principles result. It can make use of the Wannier function Hamiltonian, which can be constructed from many first principles codes, or localized orbital based codes. Solution method: It uses the magnetic force theorem and takes the rigid spin rotation as a perturbation to the electronic structure. The energy variation is calculated from the Green's functions from tight-binding like Hamiltonian based on Wannier functions or localized orbitals. Additional comments including restrictions and unusual features: Isotropic exchange, anisotropic exchange, and Dzyaloshinskii–Moriya interactions can all be computed with the input of many DFT codes through the interface of Wannier90, or directly from localized orbital codes. The magnetic interaction parameters up to any distance can be computed from one DFT calculation. A minimum user-input is required which provides a black-box like experience. It generates output for several spin dynamics codes and thus bridges the first principles electronic structure simulation with the large scale spin dynamics simulation. © 2021 Elsevier B.V.

  • The effect of Ni and Fe on the decomposition of yttrium doped barium zirconate thin films

    Jennings D., Ricote S., Caicedo J.M., Santiso J., Reimanis I. Scripta Materialia; 201 (113948) 2021. 10.1016/j.scriptamat.2021.113948. IF: 5.079

    Nanomaterials Growth Unit

    Transition metal dopants like Ni and Fe are known to influence the densification and microstructure evolution of yttrium doped barium zirconate (BZY), and understanding their behavior impacts the use of BZY in applications like protonic ceramic fuel cells and catalysts. This work investigates the effects of Ni and Fe on the evolution of BZY thin films in high temperature (1175°C), reducing environments, where BZY faceting and decomposition is observed. It is shown that the addition of Ni promotes film decomposition, whereas Fe prevents decomposition. The effects of the dopants on film decomposition are consistent with thermodynamic predictions that indicate the addition of Fe to the B-site of the perovskite structure diminishes the Gibbs free energy change for decomposition. © 2021

  • 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

  • The Microbiome Meets Nanotechnology: Opportunities and Challenges in Developing New Diagnostic Devices

    Fuentes-Chust C., Parolo C., Rosati G., Rivas L., Perez-Toralla K., Simon S., de Lecuona I., Junot C., Trebicka J., Merkoçi A. Advanced Materials; 33 (18, 2006104) 2021. 10.1002/adma.202006104. IF: 27.398

    Nanobioelectronics and Biosensors

    Monitoring of the human microbiome is an emerging area of diagnostics for personalized medicine. Here, the potential of different nanomaterials and nanobiosensing technologies is reviewed for the development of novel diagnostic devices for the detection and measurement of microbiome-related biomarkers. Moreover, the current and future landscape of microbiome-based diagnostics is defined by exploring the advantages and disadvantages of current nanotechnology-based approaches, especially in the context of developing point-of-care (PoC) devices that would meet the international guidelines known as REASSURED (Real-time connectivity; Ease of specimen collection; Affordability; Sensitivity; Specificity; User-friendliness; Rapid & robust operation; Equipment-free; and Deliverability). Finally, the strategies of the latest international scientific consortia working in this field are analyzed, the current microbiome diagnostics market are reported and the principal ethical, legal, and societal issues related to microbiome R&D and innovation are discussed. © 2021 Wiley-VCH GmbH

  • Thermal conductivity of benzothieno-benzothiophene derivatives at the nanoscale

    Gueye M.N., Vercouter A., Jouclas R., Guérin D., Lemaur V., Schweicher G., Lenfant S., Antidormi A., Geerts Y., Melis C., Cornil J., Vuillaume D. Nanoscale; 13 (6): 3800 - 3807. 2021. 10.1039/d0nr08619c. IF: 6.895

    Theoretical and Computational Nanoscience

    We study by scanning thermal microscopy the nanoscale thermal conductance of films (40-400 nm thick) of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). We demonstrate that the out-of-plane thermal conductivity is significant along the interlayer direction, larger for BTBT (0.63 ± 0.12 W m-1 K-1) compared to C8-BTBT-C8 (0.25 ± 0.13 W m-1 K-1). These results are supported by molecular dynamics calculations (approach to equilibrium molecular dynamics method) performed on the corresponding molecular crystals. The calculations point to significant thermal conductivity (3D-like) values along the 3 crystalline directions, with anisotropy factors between the crystalline directions below 1.8 for BTBT and below 2.8 for C8-BTBT-C8, in deep contrast with the charge transport properties featuring a two-dimensional character for these materials. In agreement with the experiments, the calculations yield larger values in BTBT compared to C8-BTBT-C8 (0.6-1.3 W m-1 K-1versus 0.3-0.7 W m-1 K-1, respectively). The weak thickness dependence of the nanoscale thermal resistance is in agreement with a simple analytical model. This journal is © The Royal Society of Chemistry.

  • 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.

  • Thickness-Dependent Elastic Softening of Few-Layer Free-Standing MoSe2

    Babacic V., Saleta Reig D., Varghese S., Vasileiadis T., Coy E., Tielrooij K.-J., Graczykowski B. Advanced Materials; 33 (23, 2008614) 2021. 10.1002/adma.202008614. IF: 27.398

    Ultrafast Dynamics in Nanoscale Systems

    Few-layer van der Waals (vdW) materials have been extensively investigated in terms of their exceptional electronic, optoelectronic, optical, and thermal properties. Simultaneously, a complete evaluation of their mechanical properties remains an undeniable challenge due to the small lateral sizes of samples and the limitations of experimental tools. In particular, there is no systematic experimental study providing unambiguous evidence on whether the reduction of vdW thickness down to few layers results in elastic softening or stiffening with respect to the bulk. In this work, micro-Brillouin light scattering is employed to investigate the anisotropic elastic properties of single-crystal free-standing 2H-MoSe2 as a function of thickness, down to three molecular layers. The so-called elastic size effect, that is, significant and systematic elastic softening of the material with decreasing numbers of layers is reported. In addition, this approach allows for a complete mechanical examination of few-layer membranes, that is, their elasticity, residual stress, and thickness, which can be easily extended to other vdW materials. The presented results shed new light on the ongoing debate on the elastic size-effect and are relevant for performance and durability of implementation of vdW materials as resonators, optoelectronic, and thermoelectric devices. © 2021 Wiley-VCH GmbH

  • 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.

  • Transient reprogramming of postnatal cardiomyocytes to a dedifferentiated state

    Kisby T., de Lázaro I., Stylianou M., Cossu G., Kostarelos K. PLoS ONE; 16 (5 May, e0251054) 2021. 10.1371/journal.pone.0251054. IF: 2.740


    In contrast to mammals, lower vertebrates are capable of extraordinary myocardial regeneration thanks to the ability of their cardiomyocytes to undergo transient dedifferentiation and proliferation. Somatic cells can be temporarily reprogrammed to a proliferative, dedifferentiated state through forced expression of Oct3/4, Sox2, Klf4 and c-Myc (OSKM). Here, we aimed to induce transient reprogramming of mammalian cardiomyocytes in vitro utilising an OSKM-encoding non-integrating vector. Reprogramming factor expression in postnatal rat and mouse cardiomyocytes triggered rapid but limited cell dedifferentiation. Concomitantly, a significant increase in cell viability, cell cycle related gene expression and Ki67 positive cells was observed consistent with an enhanced cell cycle activation. The transient nature of this partial reprogramming was confirmed as cardiomyocyte-specific cell morphology, gene expression and contractile activity were spontaneously recovered by day 15 after viral transduction. This study provides the first evidence that adenoviral OSKM delivery can induce partial reprogramming of postnatal cardiomyocytes. Therefore, adenoviral mediated transient reprogramming could be a novel and feasible strategy to recapitulate the regenerative mechanisms of lower vertebrates. Copyright: © 2021 Kisby et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  • 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


    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

  • Tubular CoFeP@CN as a Mott–Schottky Catalyst with Multiple Adsorption Sites for Robust Lithium−Sulfur Batteries

    Zhang C., Du R., Biendicho J.J., Yi M., Xiao K., Yang D., Zhang T., Wang X., Arbiol J., Llorca J., Zhou Y., Morante J.R., Cabot A. Advanced Energy Materials; 2021. 10.1002/aenm.202100432. IF: 25.245

    Advanced Electron Nanoscopy

    The shuttle effect and the sluggish reaction kinetics of lithium polysulfide (LiPS) seriously compromise the performance of lithium–sulfur batteries (LSBs). To overcome these limitations and enable the fabrication of robust LSBs, here the use of a Mott–Schottky catalyst based on bimetallic phosphide CoFeP nanocrystals supported on carbon nitride tubular nanostructures as sulfur hosts is proposed. Theoretical calculations and experimental data confirm that CoFeP@CN composites are characterized by a suitable electronic structure and charge rearrangement that allows them to act as a Mott–Schottky catalyst to accelerate LiPS conversion. In addition, the tubular geometry of CoFeP@CN composites facilitates the diffusion of Li ions, accommodates volume change during the reaction, and offers abundant lithiophilic/sulfiphilic sites to effectively trap soluble LiPS. Therefore, S@CoFeP@CN electrodes deliver a superior rate performance of 630 mAh g−1 at 5 C, and remarkable cycling stability with 90.44% capacity retention over 700 cycles. Coin cells with high sulfur loading, 4.1 mg cm−2, and pouch cells with 0.1 Ah capacities are further produced to validate their superior cycling stability. In addition, it is demonstrated here that CoFeP@CN hosts greatly alleviate the often overlooked issues of low energy efficiency and serious self-discharging in LSBs. © 2021 Wiley-VCH GmbH

  • Tuning the Electronic Bandgap of Graphdiyne by H-Substitution to Promote Interfacial Charge Carrier Separation for Enhanced Photocatalytic Hydrogen Production

    Li J., Slassi A., Han X., Cornil D., Ha-Thi M.-H., Pino T., Debecker D.P., Colbeau-Justin C., Arbiol J., Cornil J., Ghazzal M.N. Advanced Functional Materials; 2021. 10.1002/adfm.202100994. IF: 16.836

    Advanced Electron Nanoscopy

    Graphdiyne (GDY), which features a highly π-conjugated structure, direct bandgap, and high charge carrier mobility, presents the major requirements for photocatalysis. Up to now, all photocatalytic studies are performed without paying too much attention on the GDY bandgap (1.1 eV at the G0W0 many-body theory level). Such a narrow bandgap is not suitable for the band alignment between GDY and other semiconductors, making it difficult to achieve efficient photogenerated charge carrier separation. Herein, for the first time, it is demonstrated that tuning the electronic bandgap of GDY via H-substitution (H-GDY) promotes interfacial charge separation and improves photocatalytic H2 evolution. The H-GDY exhibits an increased bandgap energy (≈2.5 eV) and exploitable conduction band minimum and valence band maximum edges. As a representative semiconductor, TiO2 is hybridized with both H-GDY and GDY to fabricate a heterojunction. Compared to the GDY/TiO2, the H-GDY/TiO2 heterojunction leads to a remarkable enhancement of the photocatalytic H2 generation by 1.35 times under UV–visible illumination (6200 µmol h−1 g−1) and four times under visible light (670 µmol h−1 g−1). Such enhancement is attributed to the suitable band alignment between H-GDY and TiO2, which efficiently promotes the photogenerated electron and hole separation, as supported by density functional theory calculations. © 2021 Wiley-VCH GmbH

  • Ultrabroadband light absorbing Fe/polymer flexible metamaterial for soft opto-mechanical devices

    Güell-Grau P., Pi F., Villa R., Nogués J., Alvarez M., Sepúlveda B. Applied Materials Today; 23 (101052) 2021. 10.1016/j.apmt.2021.101052. IF: 8.352

    Magnetic Nanostructures

    Ultrabroadband light absorbers are attracting increasing interest for applications in energy harvesting, photodetection, self-regulated devices or soft robotics. However, current absorbers show detrimental insufficient absorption spectral range, or light angle and polarization dependence. Here we show that the unexplored optical properties of highly-damped plasmonic materials combined with the infrared absorption of thin polymer films enable developing ultrabroadband light-absorbing soft metamaterials. The developed metamaterial, composed of a nanostructured Fe layer mechanically coupled to a thin polydimethylsiloxane (PDMS) film, shows unprecedented ultrabroadband and angle-independent optical absorption (averaging 84% within 300–18000 nm). The excellent photothermal efficiency and large thermal-expansion mismatch of the metamaterial is efficiently transformed into large mechanical deflections, which we exploit to show an artificial iris that self-regulates the transmitted light power from the ultraviolet to the long-wave infrared, an untethered light-controlled mechanical gripper and a light-triggered electrical switch. © 2021 The Authors

  • 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.

  • Understanding the molecular basis of 5-ht4 receptor partial agonists through 3d-qsar studies

    Castro-Alvarez A., Chávez-ángel E., Nelson R. International Journal of Molecular Sciences; 22 (7, 3602) 2021. 10.3390/ijms22073602. IF: 4.556

    Phononic and Photonic Nanostructures

    Alzheimer’s disease (AD) is a neurodegenerative disorder whose prevalence has an incidence in senior citizens. Unfortunately, current pharmacotherapy only offers symptom relief for patients with side effects such as bradycardia, nausea, and vomiting. Therefore, there is a present need to provide other therapeutic alternatives for treatments for these disorders. The 5-HT4 receptor is an attractive therapeutic target since it has a potential role in central and peripheral nervous system disorders such as AD, irritable bowel syndrome, and gastroparesis. Quantitative structure-activity relationship analysis of a series of 62 active compounds in the 5-HT4 receptor was carried out in the present work. The structure-activity relationship was estimated using three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques based on these structures’ field molecular (force and Gaussian field). The best force-field QSAR models achieve a value for the coefficient of determination of the training set of R2 training = 0.821, and for the test set R2 test = 0.667, while for Gaussian-field QSAR the training and the test were R2 training = 0.898 and R2 test = 0.695, respectively. The obtained results were validated using a coefficient of correlation of the leave-one-out cross-validation of Q2LOO = 0.804 and Q2LOO = 0.886 for force-and Gaussian-field QSAR, respectively. Based on these results, novel 5-HT4 partial agonists with potential biological activity (pEC50 8.209– 9.417 for force-field QSAR and 9.111–9.856 for Gaussian-field QSAR) were designed. In addition, for the new analogues, their absorption, distribution, metabolism, excretion, and toxicity properties were also analyzed. The results show that these new derivatives also have reasonable pharmacokinetics and drug-like properties. Our findings suggest novel routes for the design and development of new 5-HT4 partial agonists. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • 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; 5 (4, 2000707) 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

  • Valley Hall effect and nonlocal resistance in locally gapped graphene

    Aktor T., Garcia J.H., Roche S., Jauho A.-P., Power S.R. Physical Review B; 103 (11, 115406) 2021. 10.1103/PhysRevB.103.115406. IF: 3.575

    Theoretical and Computational Nanoscience

    We report on the emergence of bulk, valley-polarized currents in graphene-based devices, driven by spatially varying regions of broken sublattice symmetry, and revealed by nonlocal resistance (RNL) fingerprints. By using a combination of quantum transport formalisms, giving access to bulk properties as well as multiterminal device responses, the presence of a nonuniform local band gap is shown to give rise to valley-dependent scattering and a finite Fermi-surface contribution to the valley Hall conductivity, related to characteristics of RNL. These features are robust against disorder and provide a plausible interpretation of controversial experiments in graphene/hexagonal boron nitride superlattices. Our findings suggest both an alternative mechanism for the generation of valley Hall effect in graphene and a route towards valley-dependent electron optics, by materials and device engineering. © 2021 American Physical Society.