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Amino acid modified graphene nanosheets adsorb emerging contaminants from tap water outperforming unmodified precursors and activated carbon for carbamazepine, bisphenol A and benzophenone 4. Structure–adsorption relationships are unraveled.

In this work, we exploit Langmuir adsorption isotherms to compare the performance of different materials (adsorbents) in removing contaminants (adsorbates) from water.

Monoatomic nanosheets can form 2-dimensional channels with tunable chemical properties, for ion storage and filtering applications. Here, we demonstrate transport of K+, Na+, and Li+ cations and F- and Cl- anions on the centimeter scale in graphene oxide membranes (GOMs), triggered by an electric bias. Besides ion transport, the GOM channels foster also the aggregation of the selected ions in salt crystals, whose composition is not the same as that of the pristine salt present in solution, highlighting the difference between the chemical environment in the 2D channels and in bulk solutions.

We present an environmentally benign methodology for the covalent functionalization (arylation) of reduced graphene oxide (rGO) nanosheets with arylazo sulfones. A variety of tagged aryl units were conveniently accommodated at the rGO surface via visible light irradiation of suspensions of carbon nanostructured materials in aqueous media. Mild reaction conditions, absence of photosensitizers, functional group tolerance and high atomic fractions (XPS analysis) represent some of the salient features characterizing the present methodology. Control experiments for the mechanistic elucidation (Raman analysis) and chemical nanomanipulation of the tagged rGO surfaces are also reported.

The possibility of exfoliating graphite into graphene sheets allows the researchers to produce a material, termed "graphene paper" (G-paper), conductive as graphite but more flexible and processable. G-paper is already used for electronic applications, like conductors, antennas, and heaters, outperforming metal conductors thanks to its high flexibility, lightness, chemical stability, and compatibility with polymeric substrates. Here, the effectiveness in the use of G-paper for the realization of electrodes on flexible plastic substrates and textiles, and their applicability as amperometric sensors are demonstrated. The performance of these devices is compared with commercial platforms made of carbon-based inks, finding that they outperform commercial devices in sensing nicotinamide adenine dinucleotide (NADH), a key molecule for enzymatic biosensing; the electrodes can achieve state-of-the-art sensitivity (107.2 ?A mm cm) and limit of detection (0.6 × 10 m) with no need of additional functionalization. Thanks to this property, the stable deposition of a suitable enzyme, namely lactate dehydrogenase, on the electrode surface is used as a proof of concept of the applicability of this new platform for the realization of a biosensor. The possibility of having a single material suitable for antennas, electronics, and now sensing opens new opportunities for smart fabrics in wearable electronic applications.

Graphene nanosheets have outstanding adsorption efficiency toward organic molecules but the potential as sorbent for water purification is strongly limited by the tedious recovery of the nanosheets after the treatment, which can cause secondary contaminations. Here, we demonstrate that graphene oxide (GO) and reduced GO (rGO) nanosheets aggregation in tap water, enabling their separation by dead-end microfiltration (MF) on commercial polymeric hollow fiber modules. No evidence of GO/rGO contamination was found in microfiltered water and chemical potability of treated water was confirmed by standard protocols. Moreover, GO/rGO can be recovered (by inverting the filtration modality from IN-OUT to OUT-IN), washed and reused, this allowing the regeneration and reuse of both graphene nanosheets and the filtration module. The procedure (called here GO + MF) was optimized on tap water spiked with ofloxacin (OFLOX) or methylene blue (MB), as reference. The optimized procedure was then applied both with GO and rGO to the removal of a mixture of perfluoroalkyl substances (PFASs) from tap water at mu g/L levels, the highest concentration found in water resources abstracted for water consumption. We demonstrate that rGO + MF procedure allows to remove 138 mu g/g of total PFASs in only 30 min, i.e. an efficiency 3-5 times higher than granular activated carbon (43 mu g/g) used in real potabilization plants for PFASs removal.

It is important, but challenging, to measure the (photo)induced switching of molecules in different chemical environments, from solution through thin layers to solid bulk crystals. We compare the cis-trans conformational switching of commercial azobenzene molecules in different liquid and solid environments: polar solutions, liquid polymers, 2D nanostructures and 3D crystals. We achieve this goal by using complementary techniques: optical absorption spectroscopy, femtosecond transient absorption spectroscopy, Kelvin probe force microscopy and reflectance spectroscopy, supported by density functional theory calculations. We could observe the same molecule showing fast switching in a few picoseconds, when studied as an isolated molecule in water, or slow switching in tens of minutes, when assembled in 3D crystals. It is worth noting that we could also observe switching for small ensembles of molecules (a few attomoles), representing an intermediate case between single molecules and bulk structures. This was achieved using Kelvin probe force microscopy to monitor the change of surface potential of nanometric thin 2D islands containing ca. 106 molecules each, self-assembled on a substrate. This approach is not limited to azobenzenes, but can be used to observe molecular switching in isolated ensembles of molecules or other nano-objects and to study synergistic molecular processes at the nanoscale.

International audience; Understanding the biodegradability of graphene materials by the action of oxidative enzymes secreted by the immune cells is essential for developing applicable biomedical products based on graphene materials. Herein, we demonstrate the biodegradation of graphene oxide (GO) by recombinant eosinophil peroxidase (EPO) enzyme extracted from human eosinophils in the presence of a low concentration of hydrogen peroxide and NaBr. We compared the degradation capability of the enzyme on three different GO samples containing different degrees of oxygen functional groups on their graphenic lattices. EPO succeeded in degrading the three tested GO samples within 90 h treatment. Raman spectroscopy and transmission electron microscopy analyses provided clear-cut evidence for biodegradation of GO by EPO catalysis. Our results provide more insights into a better understanding of biodegradation of graphene materials, helping to the design of future biomedical products based on these carbon nanomaterials.

In this work keratin/poly(lactic acid) (PLA) 50/50 wt blend nanofibers with different loadings of graphene-oxide (GO) were prepared by electrospinning and tested as delivery systems of Rhodamine Blue (RhB), selected as a model of a drug. The effect of GO on the electrospinnability and drug release mechanism and kinetics was investigated. Rheological measurements carried out on the blend solutions revealed unsatisfactory compatibility between keratin and PLA under quiet condition. Accordingly, poor interfacial adhesion between the two phases was observed by SEM analysis of a film prepared by solution casting. On the contrary, keratin chains seem to rearrange under the flux conditions of the electrospinning process thus promoting better interfacial interactions between the two polymers, thereby enhancing their miscibility, which resulted in homogeneous and defect-free nanofibers. The loading of GO into the keratin/PLA solution contributes to increase its viscosity, its shear thinning behavior, and its conductivity. Accordingly, thinner and more homogeneous nanofibers resulted from solutions with a relatively high conductivity coupled with a pronounced shear thinning behavior. FTIR and DSC analyses have underlined, that while the PLA/GO interfacial interactions significantly compete with the PLA/keratin ones, there are no significant effects of GO on the structural organization of keratin in blend with the PLA. However, GO offers several advantages from the application point of view by slightly improving the mechanical properties of the electrospun mats and by slowing down the release of the model drug through the reduction of the matrix swelling.

The site-selective allylative and allenylative dearomatization of indoles with alcohols was performed under carbocatalytic regime in the presence of graphene oxide (GO, 10 wt % loading) as the promoter. Metal-free conditions, absence of stoichiometric additive, environmentally friendly conditions (H2O/CH3CN, 55 degrees C, 6 h), broad substrate scope (33 examples, yield up to 92 %) and excellent site- and stereoselectivity characterize the present methodology. Moreover, a covalent activation model exerted by GO functionalities was corroborated by spectroscopic, experimental and computational evidences. Recovering and regeneration of the GO catalyst through simple acidic treatment was also documented.

Graphene nanosheets are mechanically strong but flexible, electrically conductive and bio-compatible. Thus, due to these unique properties, they are being intensively studied as materials for the next generation of neural interfaces. Most of the literature focused on optimizing the interface between these materials and neurons. However, one of the most common causes of implant failure is the adverse inflammatory reaction of glial cells. These cells are not, as previously considered, just passive and supportive cells, but play a crucial role in the physiology and pathology of the nervous system, and in the interaction with implanted electrodes. Besides providing structural support to neurons, glia are responsible for the modulation of synaptic transmission and control of central and peripheral homeostasis. Accordingly, knowledge on the interaction between glia and biomaterials is essential to develop new implant-based therapies for the treatment of neurological disorders, such as epilepsy, brain tumours, and Alzheimer's and Parkinson's disease. This work provides an overview of the emerging literature on the interaction of graphene-based materials with glial cells, together with a complete description of the different types of glial cells and problems associated with them. We believe that this description will be important for researchers working in materials science and nanotechnology to develop new active materials to interface, measure and stimulate these cells.

International audience; Given the wide variety of potential applications of graphene oxide (GO), its consequent release into the environment poses serious concerns on its safety. The future production and exploitation of graphene in the years to come should be guided by its specific chemical-physical characteristics. The unparalleled potential of single-cell mass cytometry (CyTOF) to dissect by high-dimensionality the specific immunological effects of nanomaterials, represents a turning point in nanotoxicology. It helps us to identify the safe graphene in terms of physical-chemical properties and therefore to direct its future safe production.Here we present a high-dimensional study to evaluate two historically indicated as key parameters for the safe exploitation: functionalization and dimension. The role of lateral dimension and the amino-functionalization of GO on their immune impact were here evaluated as synergistic players. To this end, we dissected the effects of GO, characterized by a large or small lateral size (GO 1.32 μm and GO 0.13 μm, respectively), and its amino-functionalized counterpart (GONH2 1.32 μm and GONH2 0.13 μm, respectively) on fifteen cell types of human primary peripheral blood mononuclear cells (PBMCs).We describe how the smallest later size not only evokes pronounced toxicity on the pool of PBMCs compared to larger GOs but also towards the distinct immune cell subpopulations, in particular on non-classical monocytes, plasmacytoid dendritic cells (pDCs), natural killer cells (NKs) and B cells. The amino-functionalization was able to improve the biocompatibility of classical and non-classical monocytes, pDCs, NKs, and B cells. Detailed single-cell analysis further revealed a complex interaction of all GOs with the immune cells, and in particular monocyte subpopulations, with different potency depending on their physicochemical properties. Overall, by high-dimensional profiling, our study demonstrates that the lateral dimension is an important factor modulating immune cells and specifically monocyte activation, but a proper surface functionalization is the dominant characteristic in its immune effects. In particular, the amino-functionalization can critically modify graphene impact dampening the immune cell activation. Our study can serve as a guide for the future broad production and use of graphene in our everyday life.

International audience; Large area van der Waals (vdW) thin films are assembled materials consisting of a network of randomly stacked nanosheets. The multiscale structure and the two-dimensional (2D) nature of the building block mean that interfaces naturally play a crucial role in the charge transport of such thin films. While single or few stacked nanosheets (i.e., vdW heterostructures) have been the subject of intensive works, little is known about how charges travel through multilayered, more disordered networks. Here, we report a comprehensive study of a prototypical system given by networks of randomly stacked reduced graphene oxide 2D nanosheets, whose chemical and geometrical properties can be controlled independently, permitting to explore percolated networks ranging from a single nanosheet to some billions with room-temperature resistivity spanning from 10^–5 to 10^–1 Ω·m. We systematically observe a clear transition between two different regimes at a critical temperature T*: Efros–Shklovskii variable-range hopping (ES-VRH) below T* and power law behavior above. First, we demonstrate that the two regimes are strongly correlated with each other, both depending on the charge localization length ξ, calculated by the ES-VRH model, which corresponds to the characteristic size of overlapping sp2 domains belonging to different nanosheets. Thus, we propose a microscopic model describing the charge transport as a geometrical phase transition, given by the metal–insulator transition associated with the percolation of quasi-one-dimensional nanofillers with length ξ, showing that the charge transport behavior of the networks is valid for all geometries and defects of the nanosheets, ultimately suggesting a generalized description on vdW and disordered thin films.

Hydrogen (H2) sensors that can be produced en masse with cost-effective manufacturing tools are critical for enabling safety in the emerging hydrogen economy. The use of melt-processed nanocomposites in this context would allow the combination of the advantages of plasmonic hydrogen detection with polymer technology; an approach which is held back by the slow diffusion of H2 through the polymer matrix. Here, we show that the use of an amorphous fluorinated polymer, compounded with colloidal Pd nanoparticles prepared by highly scalable continuous flow synthesis, results in nanocomposites that display a high H2 diffusion coefficient in the order of 10-5 cm2 s-1. As a result, plasmonic optical hydrogen detection with melt-pressed fluorinated polymer nanocomposites is no longer limited by the diffusion of the H2 analyte to the Pd nanoparticle transducer elements, despite a thickness of up to 100 μm, thereby enabling response times as short as 2.5 s at 100 mbar (≡10 vol. %) H2. Evidently, plasmonic sensors with a fast response time can be fabricated with thick, melt-processed nanocomposites, which paves the way for a new generation of robust H2 sensors.

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Janus graphene stacks as artificial graphite allow the reversible intercalation of sodium ions., Sodium, in contrast to other metals, cannot intercalate in graphite, hindering the use of this cheap, abundant element in rechargeable batteries. Here, we report a nanometric graphite-like anode for Na+ storage, formed by stacked graphene sheets functionalized only on one side, termed Janus graphene. The asymmetric functionalization allows reversible intercalation of Na+, as monitored by operando Raman spectroelectrochemistry and visualized by imaging ellipsometry. Our Janus graphene has uniform pore size, controllable functionalization density, and few edges; it can store Na+ differently from graphite and stacked graphene. Density functional theory calculations demonstrate that Na+ preferably rests close to -NH2 group forming synergic ionic bonds to graphene, making the interaction process energetically favorable. The estimated sodium storage up to C6.9Na is comparable to graphite for standard lithium ion batteries. Given such encouraging Na+ reversible intercalation behavior, our approach provides a way to design carbon-based materials for sodium ion batteries.

To analyze outcomes following major lower extremity amputations (mLEAs) for peripheral arterial obstructive disease, gangrene, infected non-healing wound and to create a risk prediction scoring system for 30-day mortality. In this single-center, retrospective, observational cohort study. All patients treated with above-the-knee amputation (AKA) or below-the-knee amputation (BKA) between January 1st, 2010 and June 30th, 2018 were identified. The primary outcome of interest was early (≤ 30 days) mortality. Secondary outcomes were postoperative complications and freedom from amputation stump revision/failure. We identified 310 (77.7%) mLEAs performed on 286 patients. There were 188 (65.7%) men and 98 (34.3%) women with a median age of 79 years (IQR, 69–83 years). We performed 257 (82.9%) AKA and 53 (17.1%) BKA. There were 49 (15.8%) early deaths, which did not differ among the age quartiles of this cohort (15.4% vs. 14.3% vs. 15.4% vs. 19.5%, P = 0.826). Binary logistic regression analysis identified age > 80 years (OR 2.24, 95% CI 1.17–4.31; P = 0.015), chronic obstructive pulmonary disease (OR 2.12, 95% CI 1.11–4.06; P = 0.023), and hemodialysis (OR 2.52, 95% CI 1.15–5.52; P = 0.021) to be associated with early mortality. The final score (range 0–10) identified two subgroups with different mortality at 30 days: lower-risk (score P Graphic abstract

The electrochemical exfoliation of graphite is one of the cheapest and most tunable industrial techniques to produce graphene nanosheets with a tunable degree of oxidation and solubility. Anodic oxidation allows high-yield production of electrochemically exfoliated graphene oxide (EGO) in either acid or salt solutions, with the key role played by ions electrochemically driven in between the graphene sheets. This chemical intercalation is followed by a mesoscale mechanical exfoliation process, which is key for the high yield of the process, but which is still poorly understood. In this work, we use Raman spectroscopy to simultaneously monitor the intercalation and oxidation processes taking place on the surface of highly ordered pyrolytic graphite (HOPG) during electrochemical exfoliation. The mechanism of EGO formation in either acidic (0.5 M H2SO4) or neutral (0.5 M Li2SO4) electrolytes through blistering and cracking steps is discussed and described. This process is also compared to the non-destructive intercalation of graphite in an organic electrolyte (1 M NaClO4 in acetonitrile). The results obtained show how high exfoliation yield and low defectivity can be achieved by the combination of efficient, non-destructive intercalation followed by chemical decomposition of the intercalants and gas production.

We describe an electrochemical device for the simultaneous monitoring of glucose and lactate in sweat, based on enzymatic sensors exploiting capillary flow to induce continuous, stable sensing. The enzymes, namely glucose oxidase and lactate oxidase, were anchored to a graphene oxide and chitosan composite (GO-Ch) of original synthesis, to achieve stable deposition of the bioreceptors on the electrochemical platform. We tested both biosensors on a realistic device architecture: they were embedded in a nitrocellulose strip, to exploit capillary force to induce a continuous flux of sweat on the sensor platform, ensuring the constant renewal of sample. We could achieve good sensitivity at potentials close to zero by using Prussian Blue as redox mediator, thus avoiding interference from other chemical species present in the complex matrix. The sensing signal was stable and linear over two hours in a concentration range of glucose and lactate between the limit of quantification (32 and 68 nM, respectively) and the upper limit of linearity (3.8 and 50.0 mM, respectively). The device is simple, robust, stable, and can be easily worn without the direct contact of the active part with the skin, making it suitable for simultaneous monitoring of glucose and lactate in human sweat.

Lithium-sulfur (Li-S) batteries are considered one of the most promising energy storage technologies, possibly replacing the state-of-the-art lithium-ion (Li-ion) batteries owing to their high energy density, low cost, and eco-compatibility. However, the migration of high-order lithium polysulfides (LiPs) to the lithium surface and the sluggish electrochemical kinetics pose challenges to their commercialization. The interactions between the cathode and LiPs can be enhanced by the doping of the carbon host with heteroatoms, however with relatively low doping content (

The electrochemical exfoliation of graphite is one of the cheapest and most tunable industrial techniques to produce graphene nanosheets with a tunable degree of oxidation and solubility. Anodic oxidation allows high-yield production of electrochemically exfoliated graphene oxide (EGO) in either acid or salt solutions, with the key role played by ions electrochemically driven in between the graphene sheets. This chemical intercalation is followed by a mesoscale mechanical exfoliation process, which is key for the high yield of the process, but which is still poorly understood. In this work, we use Raman spectroscopy to simultaneously monitor the intercalation and oxidation processes taking place on the surface of highly ordered pyrolytic graphite (HOPG) during electrochemical exfoliation. The mechanism of EGO formation in either acidic (0.5 M H

Systems of care have been challenged to control progression of the COVID-19 pandemic. Whether this has been associated with delayed reperfusion and worse outcomes in French patients with ST-segment elevation myocardial infarction (STEMI) is unknown.Aim: To compare the rate of STEMI admissions, treatment delays, and outcomes between the first peak of the COVID-19 pandemic in France and the equivalent period in 2019.Methods: In this nationwide French survey, data from consecutive STEMI patients from 65 centres referred for urgent revascularization between 1 March and 31 May 2020, and between 1 March and 31 May 2019, were analysed. The primary outcome was a composite of in-hospital death or non-fatal mechanical complications of acute myocardial infarction.Results: A total of 6306 patients were included. During the pandemic peak, a 13.9±6.6% (P=0.003) decrease in STEMI admissions per week was observed. Delays between symptom onset and percutaneous coronary intervention were longer in 2020 versus 2019 (270 [interquartile range 150-705] vs 245 [140-646]min; P=0.013), driven by the increase in time from symptom onset to first medical contact (121 [60-360] vs 150 [62-420]min; P=0.002). During 2020, a greater number of mechanical complications was observed (0.9% vs 1.7%; P=0.029) leading to a significant difference in the primary outcome (112 patients [5.6%] in 2019 vs 129 [7.6%] in 2020; P=0.018). No significant difference was observed in rates of orotracheal intubation, in-hospital cardiac arrest, ventricular arrhythmias and cardiogenic shock.Conclusions: During the first peak of the COVID-19 pandemic in France, there was a decrease in STEMI admissions, associated with longer ischaemic time, exclusively driven by an increase in patient-related delays and an increase in mechanical complications. These findings suggest the need to encourage the population to seek medical help in case of symptoms., Contexte. Les systèmes de santé à travers le monde ont été fortement mis à l’épreuve afin de contrôler la progression de l’épidémie de la COVID-19. L’éventualité que la réorganisation des soins ait pu influencer les délais de reperfusion ou le devenir des patients présentant des syndromes coronaires aigus avec sus-décalage du segment ST (SCA ST +) n’a pas été explorée en France.Objectif. Comparer le taux d’admissions pour SCA ST+, les délais de traitement et enfin le devenir de ces patients entre la première vague épidémique de la COVID-19 et pendant la période similaire en 2019.Méthodes. Dans ce registre national multicentrique, les patients avec SCA ST+ provenant de 65 centres français admis en urgence pour revascularisation entre le 1e mars et le 31 mai 2020 et entre le 1e mars et le 31 mai 2019 ont été analysés. Le critère de jugement principal était un critère composite regroupant la mortalité intrahospitalière toute cause confondue et les complications mécaniques en lien avec l’infarctus.Résultats. Un total de 6 306 patients ont été inclus. Pendant le pic de la pandémie une réduction de 13,9 ± 6,6 % (P = 0,003) des admissions pour SCA ST+ a été observée par semaine. Les délais entre l’apparition des symptômes et l’angioplastie percutanée était significativement augmentés 270 (150−705) versus 245 (140−646) minutes (P = 0,013). Cette augmentation était exclusivement liée à une augmentation du temps entre l’apparition des symptômes et le premier contact médical 121 (60−360) en 2019 versus 150 (62−420) minutes en 2020 (P = 0,002). Durant cette période a été constaté un plus grand nombre de complications mécaniques (0,9 % vs 1,7 % (P = 0,029) conduisant à une augmentation significative de notre critère de jugement principal 112 patients (5,6) en 2019 vs 129 (7,6 %) en 2020 (P = 0,018).Conclusions. Pendant le premier pic de la pandémie il a été constaté : une diminution du taux de SCA ST + associé à un temps d’ischémie prolongé, poussé par l’augmentation du temps entre l’apparition des symptômes et le premier contact médical et enfin un plus grand nombre de complications mécaniques. Ces observations suggèrent la nécessité d’encourager la population à consulter au moindre symptôme inquiétant.

A simple, fast, and reproducible analyte detection using low amounts of solution is nowadays possible thanks to the presence on the market of disposable screen-printed electrodes: they are widely employed in academic research as well as in industrial applications, as they are suited for a wide range of purposes. They are available in different geometries, on flexible or solid supports and with working electrodes consisting of conventional and non-conventional materials; in particular, different nanosized materials can be included in the printed ink or added as a coating afterwards. Among the variety of nanomaterials proposed to impart effectiveness to the sensor response, graphene derivatives are increasingly exploited in electrochemical biosensing, since their nanosized dimensions allow a great number of oxidized residues to be well exposed to the surrounding environment; these moieties are responsible for the activation of electrocatalytic processes toward several species, i.e. a decrease of the oxidation or reduction potentials of the analyte with respect to pristine carbon electrodes. To fully exploit the electrocatalytic performance of this nanosized material, we developed flexible, self-standing three-electrode cells entirely made of graphene. They were realised from pristine graphene paper (G-paper), a flexible, electrically conductive, paper-like material which has a large surface area, high porosity and can be easily obtained in different shapes. We demonstrated that G-paper electrodes can be successfully employed in electrochemical sensing, thanks to electrochemical tests with a benchmark redox species. In addition, their electrocatalytic properties were studied towards the detection of the two main products of enzymatic reactions, namely nicotinamide adenine dinucleotide (NADH), a co-factor for many dehydrogenase-type enzymes, and of H2O2, a product of many oxidase-based enzymatic reactions. These tests demonstrate the possible advantages in the use of these new devices with respect to those present on the market.

Energy-storage materials can be assembled directly on the electrodes of a battery using electrochemical methods, this allowing sequential deposition, high structural control, and low cost. Here, a two-step approach combining electrophoretic deposition (EPD) and cathodic electrodeposition (CED) is demonstrated to fabricate multilayer hierarchical electrodes of reduced graphene oxide (rGO) and mixed transition metal sulfides (NiCoMnSx). The process is performed directly on conductive electrodes applying a small electric bias to electro-deposit rGO and NiCoMnSx in alternated cycles, yielding an ideal porous network and a continuous path for transport of ions and electrons. A fully rechargeable alkaline battery (RAB) assembled with such electrodes gives maximum energy density of 97.2 Wh kg−1 and maximum power density of 3.1 kW kg−1, calculated on the total mass of active materials, and outstanding cycling stability (retention 72% after 7000 charge/discharge cycles at 10 A g−1). When the total electrode mass of the cell is considered, the authors achieve an unprecedented gravimetric energy density of 68.5 Wh kg−1, sevenfold higher than that of typical commercial supercapacitors, higher than that of Ni/Cd or lead–acid Batteries and similar to Ni–MH Batteries. The approach can be used to assemble multilayer composite structures on arbitrary electrode shapes.

Major breakthroughs in batteries would require the development of new composite electrode materials, with a precisely controlled nanoscale architecture. However, composites used for energy storage are typically a disordered bulk mixture of different materials, or simple coatings of one material onto another. We demonstrate here a new technique to create complex hierarchical electrodes made of multilayers of vertically aligned nanowalls of hematite (Fe2O3) alternated with horizontal spacers of reduced graphene oxide (RGO), all deposited on a 3D, conductive graphene foam. The RGO nanosheets act as porous spacers, current collectors and protection against delamination of the hematite. The multilayer composite, formed by up to 7 different layers, can be used with no further processing as an anode in Li-ion batteries, with a specific capacity of up to 1175 A h cm(-2) and a capacity retention of 84% after 1000 cycles. Our coating strategy gives improved cyclability and rate capacity compared to conventional bulk materials. Our production method is ideally suited to assemble an arbitrary number of organic-inorganic materials in an arbitrary number of layers.

Defect-rich graphene oxide (dGO) was used as sorbent for organic contaminants of emerging concern in tap water, including drugs and dyes, and the performance compared to those of lower-defects graphene types. The role of holes and carbonyl- carboxylic groups on graphene nanosheets surface on the adsorption mechanism and efficiency was investigated. dGO showed enhanced adsorption capacity toward two fluoroquinolone antibiotics (ofloxacin, OFLOX, and ciprofloxacin, CIPRO) in tap water with a maximum capacity of 650 mg/g, compared to 204 mg/g for Hummers derived commercial GO (hGO) and 125 mg/g for less defected Brodie derived GO (bGO) for OFLOX. The role of defects on the selective adsorption of OFLOX was also modelled by MD simulations, highlighting a mechanism mainly driven by the shape complementarity between the graphene holes and the molecules. Adsorption isotherms revealed different adsorption model for dGO, with a Langmuir fitting for dGO and BET fitting for all the other investigated samples. The maximum adsorption capacity of dGO for OFLOX was about six times higher than that of Granular Activated Carbon (95 mg/g), the industrial adsorption standard technology. Finally, it was also demonstrated that dGO can be recovered from treated water by ultrafiltration, this preventing secondary contamination risks and enabling safe use of graphene nanosheets for water purification.

Carbon-based materials (CBMs), such as graphene, nanodiamonds, carbon fibers, and carbon dots, have attracted a great deal scientific attention due to their potential as biomedical tools. Following exposure, particularly intravenous injection, these nanomaterials can be recognized by immune cells. Such interactions could be modulated by the different physicochemical properties of the materials (e.g. structure, size, and chemical functions), by either stimulating or suppressing the immune response. However, a harmonized cutting-edge approach for the classification of these materials based not only on their physicochemical parameters but also their immune properties has been missing. The European Commission-funded G-IMMUNOMICS and CARBO-IMmap projects aimed to fill this gap, developing a functional pipeline for the qualitative and quantitative immune characterization of graphene, graphene-related materials (GRMs), and other CBMs. The goal was to open breakthrough perspectives for the definition of the immune profiles of these materials. Here, we summarize our methodological approach, key results, and the necessary multidisciplinary expertise ranging across various fields, from material chemistry to engineering, immunology, toxicology, and systems biology. G-IMMUNOMICS, as a partnering project of the Graphene Flagship, the largest scientific research initiative on graphene worldwide, also complemented the studies performed in the Flagship on health and environmental impact of GRMs. Finally, we present the nanoimmunity-by-design concept, developed within the projects, which can be readily applied to other 2D materials. Overall, the G-IMMUNOMICS and CARBO-IMmap projects have provided new insights on the immune impact of GRMs and CBMs, thus laying the foundation for their safe use and future translation in medicine.

We describe a nanocomposite material for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH), a coenzyme involved in redox reactions of all living cells and in the detection of many organic species by electrochemical biosensors. The composite is made of nanosheets of electrochemically exfoliated graphene oxide (EGO) covalently functionalized with dopamine (DP) molecules. The EGODP material finally obtained is rich of 1,2-dihydroxyphenyl moieties and is able to detect NADH at a particular low potential value with higher sensitivity with respect to pristine EGO. To study the effectiveness of 1,2-dihydroxyphenyl moieties in inducing electrocatalytic oxidation of NADH, we combined standard voltammetric techniques with UV–Vis absorption spectroelectrochemistry, which allowed us to measure the variations in composition occurring at the electrode|solution interface, i.e. to measure the consumption rate of NADH. Spectroelectrochemical tests performed by polarising the electrode at a fixed potential value were finally used to compare the performance of EGODP with both EGO and EGO-DP blend (MIX) for the detection of NADH. The covalently functionalized EGO (EGODP) shows sensitivity to NADH up to 300 M−1, around 180 % and 140 % better than either pristine EGO or MIX, respectively., Spanish Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDERUE), Ministerio de Ciencia, Innovación y Universidades (RED2018-102412-T) and Junta de Castilla y León (Grant BU297P18).

Fiber-reinforced composites (FRC) are nowadays one of the most widely used class of high-tech materials. In particular, sporting goods, cars and the wings and fuselages of airplanes are made of carbon fiber reinforced composites (CFRC). CFRC are mature commercial products, but are still challenging materials. Their mechanical and electrical properties are very good along the fiber axis, but can be very poor perpendicular to it; interfacial interactions have to be tailored for specific applications to avoid crack propagation– and delamination; fiber production includes high-temperature treatments of adverse environmental impact, leading to high costs. Recent research work shows that the performance of CFRC can be improved by addition of graphene or related 2-dimensional materials (GRM). Graphene is a promising additive for CFRC because: 1) Its all-carbon aromatic structure is similar to the one of carbon fiber (CF). 2) Its 2-dimensional shape, high aspect ratio, high flexibility and mechanical strength allow it to be used as a coating on the surface of fiber, or as a mechanical/electrical connection between different fiber layers. 3) Its tunable surface chemistry allows its interaction to be enhanced with either the fiber or the polymer matrix used in the composite and 4) in contrast to carbon fibers or nanotubes, it is easily produced on a large scale at room temperature, without metal catalysts. Here, we summarize the key strategic advantages that could be obtained in this way, and some of the recent results that have been obtained in this field within the Graphene Flagship project and worldwide.

Graphene oxide (GO) coated electrodes provide an excellent platform for enzymatic glucose sensing, induced by the presence of glucose oxidase and an electrochemical transduction. Here, we show that the sensitivity of GO layers for glucose detection redoubles upon blending GO with chitosan (GO+Ch) and increases up to eight times if covalent binding of chitosan to GO (GO−Ch) is exploited. In addition, the conductivity of the composite material GO−Ch is suitable for electrochemical applications without the need of GO reduction, which is generally required for GO based coatings. Covalent modification of GO is achieved by a standard carboxylic activation/amidation approach by exploiting the abundant amino pendants of chitosan. Successful functionalization is proved by comparison with an ad-hoc synthesized control sample realized by using non-activated GO as precursor. The composite GO−Ch was deposited on standard screen-printed electrodes by a drop-casting approach. Comparison with a chitosan-GO blend and with pristine GO demonstrated the superior reliability and efficiency of the electrochemical response for glucose as a consequence of the high number of enzyme binding sites and of the partial reduction of GO during the carboxylic activation synthetic step.

Due to water depletion and increasing level of pollution from standard and emerging contaminants, the development of more efficient purification materials and technology for drinking water treatment is a crucial challenge to be addressed in the near future. Graphene oxide (GO) has been pointed as one of the most promising materials to build structure and devices for new adsorbents and filtration systems. Here, we analyzed two types of GO doped 3D chitosan-gelatin aerogels with GO sheets embedded in the bulk or deposited on the surface. Through combined structural characterization and adsorption tests on selected proxies of drinking water micropollutants, we compared both GO-embedded and GO-coated materials and established the best architecture for achieving enhanced removal efficiency toward contaminants in water. To evaluate the best configuration, we studied the adsorption capacity of both systems on two organic molecules (i.e., fluoroquinolonic antibiotics ofloxacin and ciprofloxacin) and a heavy metal (lead Pb2+) of great environmental relevance and with already proved high affinity for GO. The Pb monolayer maximum adsorption capacity q(max) was 11.1 mg/g for embedded GO aerogels and 1.5 mg/g in coated GO-ones. Only minor differences were found for organic contaminants between coating and embedding approaches with an adsorption capacity of 5-8 mg/g and no adsorption was found for chitosan-gelatin control aerogels without GO. Finally, potential antimicrobial effects were found particularly for the GO-coated aerogels materials, thus corroborating the multifunctionality of the newly developed porous structures. (C) 2020 Elsevier Ltd. All rights reserved.

Extraction of proteins from blood biological fluids requires the removal of large aggregates or cells by membrane filtration. However, conventional filters, based on simple size exclusion, do not allow to remove small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO) layer can be firmly immobilized either inside or outside polyethersulfone-polyvinylpirrolidinone hollow fibers (PES) modules and that the resulting core-shell structure inherits the microfiltration ability of PES and the adsorption selectivity of GO. GO nanosheets were deposited on fiber surface by filtration of a GO suspension through a PES cartridge (cut-off 0.1-0.2 ?m), then fixed on it by thermal annealing at 80°C, rendering them insoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outer modified hollow fibers (HF-GO) were tested by performing filtration on water spiked with bovin serum albumin (BSA, 66KDa, ?15 nm sized), monodisperse polystyrene nanoparticles (52 nm and 303 nm sized), water contaminated with two quinolonic antibiotics (ciprofloxacin and ofloxacin) and rhodamine B (RhB). These tests showed that microfiltration capability of PES was retained by HFGO, in addition the GO coating can capture the molecular contaminants while letting through BSA and smaller Polystyrene nanoparticles. Combined XRD, molecular modelling and adsorption experiments show the separation mechanism does not rely only on a physical size exclusion, but it involves intercalation of solute molecules between GO layers.

The effect of 1-pyrenesulfonicacid sodium salt (1-PSA), tetracyanoethylene (TCNE) and tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) on charge transport properties of reduced graphene oxide (RGO) is examined by measuring the transfer characteristics of field-effect transistors and co-planar time-of-flight photocurrent technique. Evidence of p-type doping and a reduction of mobility of electrons in RGO upon deposition of these materials is observed. Time-resolved photocurrent measurements show a reduction in electron mobility even at submonolayer coverage of these materials. The variation of transit time with different coverages reveals that electron mobility decreases with increasing the surface coverage of 1-PSA, TCNE and F4-TCNQ to a certain extent, while at higher coverage the electron mobility is slightly recovered. All three molecules show the same trend in charge carrier mobility variation with coverage, but with different magnitude. Among all three molecules, 1-PSA acts as weak electron acceptor compared to TCNE and F4-TCNQ. The additional fluorine moieties in F4-TCNQ provides excellent electron withdrawing capability compared to TCNE. The experimental results are consistent with the density functional theory calculations.