Search

International audience; This work describes the preparation of ternary bismuth ferrite oxide nanoparticles (Bi2Fe4O9 NPs) with an enzyme mimetic activity for dopamine (DA) qualitative and quantitative detection. Bi2Fe4O9 NPs were prepared using a facile, low cost, and one-pot hydrothermal treatment. The chemical composition, morphology, and optical properties of Bi2Fe4O9 nanozyme were characterized using different techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction pattern (XRD), X-ray photoelectron spectroscopy (XPS), thermo-gravimetric analysis (TGA), dynamic light scattering (DLS), field-emission scanning electron microscopy (FESEM) imaging, FESEM-energy dispersive X-ray spectroscopy (EDS), UV–vis absorption, and fluorescence emission spectroscopy. Bi2Fe4O9 NPs were utilized to catalyze the oxidation of a typical chromogenic peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), to form the blue-colored oxidized product (oxTMB), in the presence of hydrogen peroxide (H2O2). All reactions occurred in acetate buffer solution (pH 3.5) to generate hydroxyl radicals (•OH) and the kinetics were followed by UV–vis absorbance at 654 nm. The steady-state kinetic parameters were obtained from the Michaelis-Menten equation and exhibited a good catalytic efficiency of Bi2Fe4O9 NPs as enzyme mimetics. Michaelis–Menten constant (Km) values were estimated as 0.07 and 0.73 mM for TMB and H2O2, respectively. The presented method is efficient, rapid, cost-effective, and sensitive for the colorimetric detection of dopamine with a linear range (LR) from 0.15 to 50 μM and a detection limit (LOD) of 51 nM. The proposed colorimetric sensor was successfully applied for the detection of different concentrations of dopamine in spiked fetal bovine serum (FBS) and horse serum (HS) samples. It is anticipated that Bi2Fe4O9 nanozyme holds great potential in biomedical analysis and diagnostic applications of dopamine-related diseases.

International audience; DNA-based aptamers are widely employed as bioreceptors, owing to their tuneable affinity and specificity towards their targets. The use of peptide nucleic acids (PNAs) has instead proven challenging for this purpose, due to the absence of selection methods for the independent discovery of suitable receptors and due to the difficult mimicry of established DNA-based ones. Despite that PNAs exceed homologous DNA or RNA in terms of complementary base pairing, they can fail to reproduce alternative modes of binding because of their different structural features. The remarkable stability and charge distribution of PNAs could be beneficial to produce sensing bioreceptors, especially in the development of electronic devices such as field-effect transistor-based (FET) biosensors. We hereby report for the first time a high-affinity PNA aptamer for cardiac Troponin I (cTnI), a biomarker of acute myocardial infarction, able to interact with this specific protein in the picomolar range. The PNA aptamer was immobilized onto a graphene-based FET (gFET) transducer, and its ability in the direct detection of cTnI was compared with that of a DNA-based one of the same sequence. Similar dissociation constants were recorded for both receptors in 0.01 × PBS, as well as comparable detection limits of 6.0 ± 1.0 pg mL-1 (PNA aptamer) and 3.3 ± 0.7 pg mL-1 (DNA aptamer). Apart from the non-trivial demonstration that a PNA can behave as an aptamer, the tested receptor proved to be more consistent upon working in more complex biological matrices.

The present paper describes the first successful synthesis of an inorganic nanocomposite by grafting of cobalt (II) phthalocyanine (CoPc) on the core-shell Ni/NiO (NNO) semiconductor for the photocatalytic reduction of CO2 to methanol under visible illumination using triethylamine as a sacrificial donor. The synthesised photocatalyst exhibited a remarkable enhancement in the yield of methanol as compared to the semiconductor Ni/NiO and CoPc for CO2 reduction under identical conditions. The maximum yield of methanol was found to be 3641.2 μmol/g with the conversion rate of 151.7 μmol g−1 h−1 which was much higher than that observed with CoPc and semiconductor alone under identical experimental conditions. Furthermore, the synthesised nanocomposite showed superior activity as compared to the previously reported organic semiconductor bound cobalt complex photocatalyst. The composite photocatalyst was found to be highly stable which showed consistent recyclability for four runs without any significant loss in activity.

International audience; A polyaniline@Fe-ZSM-5 composite was synthesized via an in situ interfacial polymerization procedure. The morphology, crystallinity, and structural features of the as-developed PANI@Fe-ZSM-5 composite were assessed using scanning electron microscopy – energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The composite was efficiently employed for the first time as an adsorbent to adsorb Orange G (OG) dyestuff from water. The OG dye adsorption performance was investigated as a function of several operating conditions. The kinetic study demonstrated that a pseudo-second-order model was appropriate to anticipate the OG adsorption process. The maximum adsorption capacity was found to be 217 mg/g. The adsorption equilibrium data at different temperatures were calculated via advanced statistical physics formalism. The entropy function indicated that the disorder of OG molecules improved at low concentrations and lessened at high concentrations. The free enthalpy and internal energy functions suggested that the OG adsorption was a spontaneous process and physisorption in nature. Regeneration investigation showed that the PANI@Fe-ZSM-5 could be effectively reused up to five cycles. The main results of this work provided a deep insight on the experimental study supported by advanced statistical physics prediction for the adsorption of Orange G dye onto the novel polyaniline@Fe-ZSM-5 hybrid composite. Additionally, the experimental and advanced statistical physics findings stated in this study may arouse research interest in the field of wastewater treatment.

International audience; In the last years, carbon-based nanomaterials have attracted considerable attention in a wide range of fields, particularly in biomedicine, owing to their remarkable photo-physical and chemical properties. In this study, we demonstrate that amine-terminated carbon dots (CDs-NH2) functionalized with ampicillin (AMP) offer a new perspective for antibacterial treatment. The amine-functionalized carbon dots were used as a carrier for immobilization and delivery of ampicillin (CDs-AMP) and as a visible light-triggered antibacterial material. Additionally, AMP immobilization on the CDs-NH2 surface improves its stability in solution as compared to free AMP. The AMP conjugated CDs platform combines the antibacterial function of AMP and conserves the intrinsic theranostic properties of CDs-NH2. Therefore, the AMP immobilized onto CDs-NH2 surface together with the generation of moderate quantities of reactive oxygen species under visible light illumination is very effective to inactivate the growth of Escherichia coli.

In the present work, a cobalt phthalocyanine-supported reduced graphene oxide material (rGO-CoPc) was used as a catalyst for the degradation of rhodamine B (RhB) and pentachorophenol (PCP) in the presence of peroxymonosulfate (PMS). Inductively coupled plasma (ICP-OES), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were employed to characterize the properties of the composite and Co loading in the material. The catalytic activity of the rGO1-CoPc1 catalyst (rGO:CoPc = 1:1) was evaluated by UV–vis absorption spectroscopy at varying PMS concentrations and catalyst dosages. The complete dye removal was achieved in 9 min by rGO1-CoPc1/PMS system with a high initiation rate constant of 1.019 min−1 using RhB (25 µM), PMS (0.1 mM) and rGO1-CoPc1 (0.5 mg/mL). The removal efficiency was found to be as high as 100% after 11 cycles, suggesting a long-lasting catalytic activity of the of rGO1-CoPc1/PMS system. Quenching experiments suggested that sulfate (SO4 −) radicals are the dominant species in the degradation process although hydroxyl (OH ) radicals are also involved in the reaction mechanism. Furthermore, the catalyst was successfully applied for the efficient degradation of pentachlorophenol (PCP). A full degradation of PCP (25 µM) was achieved within 20 min using rGO1-CoPc1 (0.5 mg/mL) and PMS (0.6 mM). This study demonstrated that the use of rGO-CoPc as a heterogeneous catalyst for PMS activation is useful for the advanced oxidation processes (AOP) for practical wastewater treatment.

In part 1 (A. Vasilescu et al., Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. Part 1: Lysozyme aggregation at pH 2 and 7.4 Electrochem. Acta, 254 (2017) 375–383) we proposed porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) in combination with differential pulse voltammetry as a new analytical tool for aggregation studies of proteins. Lysozyme was used as a model to follow its aggregation by electrochemical means at pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Part 2 of this work widens the scope of this approach by investigating a biopharmaceutical product, as the aggregation of peptide based drugs affects their therapeutic activity and can induce allergic reactions in patients. The salmon polypeptide calcitonin (sCT) was chosen as an example of a bioactive peptide with limited pharmaceutical potential due to a tendency to form cytotoxic aggregates and amyloid fibrils. For practical applications, screen printed electrodes (SPE) and flexible electrodes (FE) modified with polydiallyldimethylammonium (PDDA) and prGO by using the layer-by-layer deposition technique have been developed for the detection of sCT. The results indicate that these electrodes can differentiate between formation of amyloid aggregates of calcitonin (2 mg mL−1) in citrate buffer to no aggregation in acetate buffer. It was further demonstrated that these electrodes are able to analyze a pharmaceutical drug product of low potency, Miacalcic (8.3 μg mL−1), where no aggregation was observed.

International audience; [No abstract available]

Protein instability due to misfolding and aggregation is of big concern for protein based therapeutics because it impacts the bioavailability and immunogenicity of such drugs. The development of simple and cost-effective methods for the analysis of pharmaceutical formulations, indicating the presence or absence of protein aggregates, is consequently of high importance. This work proposes a novel electrochemical interface based on porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) allowing for the early and sensitive identification of protein aggregation by following the change in the oxidative current of the proteins. The novelty of this work lies in the exploration of the ability of GC/prGO interfaces to capture different aggregation behaviors. Lysozyme is used as a model to follow by electrochemistry its aggregation at two pH values, pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Comparing the oxidation peak of lysozyme by differential pulse voltammetry (DPV) for different electrode architectures allowed validating the higher sensitivity of the GC/prGO interface versus bare glassy electrodes or electrodes coated with non-porous reduced graphene oxide. Parallel experiments were performed by fluorescence with thioflavin T, size exclusion chromatography and Atomic Force Microscopy (AFM) imaging. These tests further highlighted the usefulness of GC/prGO electrode to visualize in a fast and reliable manner the changes in the protein structure and the differences between the processes occurring at pH 2 and pH 7.4. In particular, the ability to emphasize changes related to the first steps in aggregation that could be indicative of the aggregation course, recommend the GC/prGO electrode in combination with DPV as a new analytical tool for aggregation studies of biopharmaceuticals. Part 2 of this work will demonstrate later the utility of this approach for the analysis of a fast acting injectable human insulin formulation, Humulin R, used for diabetes treatment as well as for calcitonin.

Supercapacitors (SCs) are energy storage devices with an immense potential to resolve energy related issues. Being a low cost, durable and multifunctional material, graphene and its derivatives are the most promising candidates for SCs. Here, we report the synthesis of N-doped porous reduced graphene (N-pGr) and its use for the fabrication of all-solid-state supercapacitor (ASSC) device. The N-pGr exhibited a specific capacitance of 230 F g−1 at 1 A g−1 current density and good capacitance retention up to ∼88% even after 10,000 galvanostatic charge–discharge cycles recorded at 5 A g−1 fabricated in a solid-state supercapacitor. The synergistic effect of the porosity and N-doping is believed to be the underlying principle for the improved charge storage ability when compared to other reports. Significantly, the porous nature of N-pGr contributes in increasing the electroactive surface area for the formation of electrical double layer as well as facilitating the faster movement of electrolyte ions inside the electrode network. N-doping is believed to change the electrical properties of the electrode material and also to participate in the pseudo-capacitance which helped to boost the overall capacitance of the fabricated device. The good capacitance retention provides the room for making robust flexible solid-state supercapacitor (FSSC) with the N-pGr material.

The study reports on the preparation of polyacrylonitrile fiber paper (PANFP) functionalized with polydopamine (PD) and silver nanoparticles (Ag NPs), named as Ag NPs/PD/PANFP. The composite material was obtained via a simple two-step chemical process. First, a thin polydopamine layer was coated onto the PANFP surface through immersion into an alkaline dopamine (pH 8.5) aqueous solution at room temperature. The reductive properties of polydopamine were further exploited for the deposition of Ag NPs. The morphology and chemical composition of the composite material were characterized using scanning electron microscopy (SEM), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the nanocomposite was evaluated for the reduction of 4-nitrophenol using sodium borohydride (NaBH 4 ) at room temperature. The Ag NPs/PD/PANFP displayed good catalytic performance with a full reduction of 4-nitrophenol into the corresponding 4-aminophenol within 30 min. Moreover, the composite material exhibited a good stability up to 4 cycles without a significant loss of its catalytic activity.

Metal sulphide nanoparticles (NPs) have great potential applications in environmental remediation as they can oxidize peroxidase substrates like 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) due to the production of hydroxide radicals (OH ) via the Fenton reaction in presence of H 2 O 2 . Their good binding affinity toward heavy metal ions through their S-containing sites, causes the blockage of the active sites of the catalyst and inhibits the oxidation process of peroxidase substrate. This property can be used for the sensing of heavy metal ions. Herein, a cobalt sulphide (CoS) decorated porous reduced graphene oxide (p-rGO) nanocomposite is proposed as a novel matrix for heavy metal ions detection in aqueous medium. The nanocomposite was fabricated by adopting a simple and easy solvothermal approach. After determination of the kinetics of the as-synthesized nanocomposite for the oxidation of TMB in presence of H 2 O 2 , the matrix was further used for the colorimetric detection of heavy metal (Hg, Pb, Cd) ions in aqueous medium. Depending on the metal ion, a detection limit of 14.23 nM for Hg(II) could be reached. Furthermore, the synthesized nanocomposite was successfully utilized for the detection of heavy metal ions present in real samples.

International audience; A highly efficient, recyclable and magnetically separable core-shell structured CuZnO@Fe3O4 microsphere wrapped with reduced graphene oxide (rGO@CuZnO@Fe3O4) photocatalyst has been developed and used for the photoreduction of carbon dioxide with water to produce methanol under visible light irradiation. Owing to the synergistic effect of the components and to the presence of a thin Fe2O3 layer on Fe3O4, rGO@CuZnO@Fe3O4 4 exhibited higher catalytic activity as compared to the other possible combinations such as CuZnO@Fe3O4 2 and GO@CuZnO@Fe3O4 3 microspheres. The yield of methanol in case of using 2 and 3 as photocatalyst was found to be 858 and 1749 μmol g−1 cat, respectively. However, the yield was increased to 2656 μmol g−1 cat when rGO@CuZnO@Fe3O4 4 was used as photocatalyst under similar experimental conditions. This superior photocatalytic activity of 4 was assumed to be due to the restoration of the sp2 hybridized aromatic system in rGO, which facilitated the movement of electrons and resulted in better charge separation. The synthesized heterogeneous photocatalyst could readily be recovered by external magnet and successfully reused for six subsequent cycles without significant loss in the product yield.

A hybrid nanocomposite of MoS2 nanosheets and reduced graphene oxide (rGO) was fabricated by a facile and effective method. The morphology and structure of the nanocomposite (MoS2-rGO) were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The MoS2 nanosheets were uniformly anchored on the rGO framework with strong adhesion. A glassy carbon electrode modified by drop-casting with MoS2-rGO was used for the electrochemical oxidation of cysteamine (CA) in the presence of uric acid (UA). Under optimum conditions, the anodic peak current of CA shows a linear relation with the CA concentration between 0.01 and 20μM with a detection limit of 7nM. The proposed electrochemical sensor was used for determination of CA in human plasma.

Lysozyme is an enzyme found in biological fluids, which is upregulated in leukemia, renal diseases as well as in a number of inflammatory gastrointestinal diseases. We present here the development of a novel lysozyme sensing concept based on the use of Micrococcus lysodeikticus whole cells adsorbed on graphene oxide (GO)-coated Surface Plasmon Resonance (SPR) interfaces. M. lysodeikticus is a typical enzymatic substrate for lysozyme. Unlike previously reported sensors which are based on the detection of lysozyme through bioaffinity interactions, the bioactivity of lysozyme will be used here for sensing purposes. Upon exposure to lysozyme containing serum, the integrity of the bacterial cell wall is affected and the cells detach from the GO based interfaces, causing a characteristic decrease in the SPR signal. This allows sensing the presence of clinically relevant concentrations of lysozyme in undiluted serum samples.

Nickel oxide nanoparticles were grafted on reduced graphene oxide via simultaneous reduction of graphene oxide and nickel salt in a single step reaction. The synthesized material (rGO/NiO) was found to be efficient visible light active photocatalyst for the reduction of nitroaromatic derivatives to their corresponding amino compounds. Hydrazine monohydrate provided necessary protons and electrons for the targeted reaction. After completion of the reaction, the photocatalyst could readily be recovered by simple external magnet and could be reused for six runs without any significant loss of its activity. More importantly, the photocatalyst did not show any leaching during the reaction as confirmed by ICP-AES analysis of the recovered catalyst.

International audience; In this current paper, we report a new type of heterogeneous molybdenum (+6) complex, prepared by covalent grafting of cis-dioxo‑molybdenum (VI) pyridylimine complex on the surface of MnFe2O4 nanoparticles (NP) and characterized using various physicochemical techniques. The recyclable prepared nanocatalyst was tested for sulfoxidation of sulfides and epoxidation of alkenes under solvent-free condition. The catalyst exhibited high turnover frequency for the oxidization of cyclooctene and cyclohexene (10,850 h−1) and thioanisole and dimethyl sulfide (41,250 h−1). The synthesized catalyst was found highly efficient, retrievable and eco-friendly catalyst for the (ep)oxidation of alkenes and sulfides in excellent yields in a short time. Furthermore, the synthesized nanocatalyst can be reused for four runs without apparent loss of its catalytic activity in the oxidation reaction. © 2021 Elsevier B.V.

International audience; The development of a skin-mounted patch capable of controlled transcutaneous delivery of therapeutics through thermal activation provides a unique solution for the controlled release of active principles over long-term periods. Here, we report on a flexible transdermal patch for photothermal triggered release of ondansetron (ODS), a commonly used drug for the treatment of chemotherapy-induced nausea and vomiting and used as model compound here. To achieve this, a dispersion of ODS-loaded reduced graphene oxide (rGO-ODS) nanosheets were deposited onto Kapton to produce a flexible polyimide-based patch. It is demonstrated that ODS loaded Kapton/rGO patches have a high drug delivery performance upon irradiation with a continuous laser beam at 980 nm for 10 min due to an induced photothermal heating effect. The ability of ODS impregnated Kapton/rGO patches as transdermal delivery scaffolds for ODS across the skin is in addition investigated using porcine ear skin as a model. We show that the cumulative quantity and flux of ODS passing the skin are highly depending on the laser power density used. At 5 W cm − 2 irradiation, the ODS flux across pig skin was determined to be 1.6 μg cm − 2 h − 1 comparable to other approaches. The use of tween 20 as skin enhancer could significantly increase the ODS flux to 13.2 μg cm − 2 h − 1. While the skin penetration enhancement is comparable to that obtained using other well-known permeation enhancers, the actual superiority and interest of the proposed approach is that the Kapton/rGO photoactivatable skin patch can be loaded with any drugs and therapeutics of interest, making the approach extremely versatile. The on demand delivery of drugs upon local laser irradiation and the possibility to reload the interface with the drug makes this new drug administration route very appealing.

Nanodiamonds (NDs) are among the most promising new carbon-based materials for various applications. Inspired by the remarkable adhesive ability of dopamine, a feasible approach was developed for the preparation of superhydrophobic NDs particles. The strategy is based on coating hydroxylated NDs with polydopamine (PDA) and subsequent reaction with 1 H ,1 H ,2 H ,2 H -perfluorodecanethiol (PFDT). The resulting f -PDA modified NDs (NDs- f PDA) were firmly anchored onto the skeleton of commercial polyurethane (PU) sponge due to the excellent adhesive ability of PDA. Meanwhile, the as-prepared sponge showed superhydrophobic property, oil/water separation behavior and high organic adsorption capacity. Due to its low cost, feasible fabrication technique, stability and excellent performance, this superhydrophobic PU–NDs- f PDA sponge represents a promising alternative for the selective removal of oil from water.

International audience; On-demand delivery of therapeutics plays an essential role in simplifying and improving patient care. The high loading capacity of reduced graphene oxide (rGO) for drugs has made this matrix of particular interest for its hybridization with therapeutics. In this work, we describe the formulation of rGO impregnated poly(ethylene glycol) dimethacrylate based hydrogels (PEGDMA-rGO) and their efficient loading with insulin. Near-infrared (NIR) light induced heating of the PEGDMA-rGO hydrogels allows for highly efficient insulin release. Most importantly, we validate that the NIR irradiation of the hydrogel has no effect on the biological and metabolic activities of the released insulin. The ease of insulin loading/reloading makes this photothermally triggered release strategy of interest for diabetic patients. Additionally, the rGO-based protein releasing platform fabricated here can be expanded towards 'on demand' release of various other therapeutically relevant biomolecules. Graphical abstract. The table of contents entry: Poly(ethylene glycol) based hydrogels impregnated with rGO allow efficient loading and 'on demand' photothermal release of insulin while preserving its biological and metabolic activity.

Bimetallic nanoparticles (NPs) in several instances have resulted in improved catalytic properties when compared to the monometallic analogues. This paper reports on a wet-chemistry approach for the synthesis of reduced graphene oxide (rGO) nanosheets decorated with bimetallic Cu-Ag NPs. The nanocomposite possesses the advantages of combining rGO and metallic NPs and exhibits excellent intrinsic peroxidase like activity, which can be used to catalyse the reaction of peroxidase substrates such as 3,3′,5,5′-tetramethylbenzidine (TMB) in presence of hydrogen peroxide (H 2 O 2 ). A combination of the peroxidase-like activity of the Cu-Ag/rGO nanostructures with glucose oxidase (GluO x ), allowed the construction of a sensitive and a selective colorimetric assay for glucose detection in blood serum with a detection limit of 3.8 μM. The monometallic analogues displayed a detection limit of 7.9 μM (Ag/rGO) and 9.7 μM (Cu/rGO). In addition, the Cu-Ag/rGO nanostructures were also successfully applied for sensing ascorbic acid with a detection limit of 3.6 μM.

Electrophoretic deposition (EPD) of graphene-based nanomaterials has become an attractive strategy for the controlled deposition of thin films onto substrates for various applications. In this work, we demonstrate that application of an electrical potential to gold interfaces immersed in an aqueous suspension of graphene oxide (GO), loaded with nickel ions and insulin produces a continuous coating of an insulin impregnated reduced graphene oxide (rGO) matrix loaded with Ni(OH) 2 nanostructures (rGO/insulin/Ni(OH) 2 ). The rGO/insulin/Ni(OH) 2 coated Au electrodes exhibit excellent electrocatalytic behaviour towards glucose oxidation in alkaline medium at +0.6 V. The sensitivity towards glucose is 18.9 ± 1.5 mA mM −1 cm −2 with a detection limit of ≈5 μM. In addition, the amount of insulin integrated into the electrophoretically deposited coating is as high as 48 μg mL −1 , making the matrix of high interest for release studies. Electrochemical triggered release of the trapped insulin is achieved upon application of a negative potential to the interface. The possibility to form multifunctional coatings by EPD, incorporating catalytic nanostructures for diagnosis as well as drugs for therapy in one-step makes this approach a competitive alternative to other surface coating strategies.

The release of drugs in a controlled manner over long-term periods has been recognized as one of the most promising biomedical technologies for treatment of certain types of diseases. Medical conditions such as cancer, diabetes and chronic pain require medications that must be dosed intermittently on demand and over a long period of time. The use of an electrical signal is considered as an attractive way when drug delivery on demand is requested. The approach is simple, safe, and inexpensive and has a wide range of possibilities to trigger the release. Changing the bias of the applied potential, the current density, using continuous or pulsed conditions, negative or positive potential bias, short or long cycles all allow in a unique manner the on-demand release of drugs. Together with advances in nanotechnology, enabling the realization of miniaturized electrical systems and circuits on almost standard bases make electrically triggered drug release very appealing. While special attention has to be paid to the susceptibility of drugs to be oxidized/reduced, and influence of applied current on the behavior of cells and tissues, developments in materials science have taken these concerns into considerations. The state of the art of materials and films devoted for electrical and electrochemical activation will be presented in this review.

One-step metal-assisted electroless chemical etching of silicon substrate in aqueous NH4F/AgNO3/HNO3 solution is investigated. The effects of etching time and AgNO3 concentration on the morphology and reflectance of etched layer are studied. It is found that the morphology and reflectance depend strongly on these parameters. The lowest reflectance is obtained for 0.009-0.01źźcm p-Si(100) etched in 2M NH4F-1.89 M HNO3-0.01M AgNO3 aqueous solution for 15min. Indeed, the reflectance did not exceed the value of 0.63% in the 200-800nm range. In addition, nanostructured silicon surfaces obtained through etching using this solution are decorated with copper and silver nanoparticles and their photocatalytic activity for the degradation of rhodamine B under UV and visible light irradiation is evaluated. The highest catalytic activity is observed for samples decorated with Cu nanoparticles. This is attributed to their ability to facilitate electron-hole separation and to promote electron transfer in the photocatalytic process. Display Omitted The morphology of silicon etched is considerably influenced by AgNO3 concentration.An etched film consisting of two nanostructured layers was obtained for AgNO3 concentration of 0.02M.The lowest reflectance (

New electrode composite materials, consisting of NiMnCr layered double hydroxides (LDHs) coated on carbon spheres (CS) supported on nickel foam (NiMnCr LDHs@CS/NF), were synthesized using a two step hydrothermal process. The obtained binder-free NiMnCr LDHs@CS/NF composite was investigated as a positive electrode for supercapacitors and achieved a high specific capacity of 569 C g−1 at 3 A g−1; this value was ~6.5 times that of CS/NF (87.9 C g−1 at 3 A g−1) and ~3.3 times that of NiMnCr LDHs/NF composite (173.2 C g−1 at 3 A g−1). The NiMnCr LDHs@CS/NF composite retained ~76% of its original capacity after 10,000 cycles, much better than ~54% achieved by NiMnCr LDHs/NF composite, suggesting good reversibility and stability. Furthermore, a hybrid supercapacitor was fabricated using NiMnCr LDHs@CS/NF as the positive electrode and FeOOH nanorods deposited on NF (FeOOH/NF) as the negative electrode. The hybrid supercapacitor displayed an energy density of 48 Wh kg−1 at a power density of 402.7 W kg−1. A home-designed windmill device was successfully driven by the as-fabricated supercapacitor device for about 25 s. Additionally, two as-fabricated hybrid supercapacitor cells in series were used to light up a yellow LED and a red LED in parallel for ~111 s and ~343 s, respectively. Taken together, these results indicate that the developed electrodes hold a promising potential in energy storage application.

In this contribution, we report a straightforward method for the preparation of magnetic polyurethane (MPU) sponge with superhydrophobic/superoleophilic properties. The MPU sponge is fabricated in a two-step process consisting of surface functionalization of PU sponge with 3,5-bis(trifluoromethyl)benzenediazonium tosylate [ADT-(CF3)2] for the enhancement of its hydrophobicity, followed by incorporation of magnetic nanoparticles modified with the same diazonium salt. The proposed functionalization scheme endows the PU sponge with superhydrophobic and magnetic properties necessary for efficient oil-in-water emulsion separation and easy recovery through the application of an external magnet. The MPU sponge exhibits high adsorption capacity (40 to 75 wt/wt) for various oils such as rapeseed and pump oils, and organic solvents. Additionally, the MPU sponge is successfully applied for the effective separation of oil-in-water emulsions. Taken together, the results obtained in this work hold promise for many environmental applications.

Advanced materials with special wettability hold promise in environmental remediation, catalysis or superfluid, and have attracted a great deal of interest in the last years. Herein, a composite material consisting of a molybdenum sulfide/polyurethane sponge (MoS2/PU) was fabricated through MoS2 nanosheets loading onto PU using high-intensity sonication and subsequent chemical functionalization by in-situ generated diazonium salts. The MoS2 enhanced the hydrophobicity and roughness of the PU sponge and its surface could be effectively modified with aryl and carbon-fluorine groups through diazonium chemistry. The resulting F-MoS2/PU interface exhibited exceptional superhydrophobic/superoleophilic wettability, and allowed to separate oil/water mixtures and eliminate selectively oil from underwater or emulsions. Besides, due to the cavitation effect of high-intensity ultrasound, the exfoliated MoS2 sheets were strongly anchored onto the PU sponge. Loading MoS2 and/or diazonium molecules did not induce any adverse effect on the adsorption capacity of the sponge with values ranging from 25 to 90 gg−1 for different organic solvents (hexane, diethyl ether, ethanol, toluene, rapeseed oil, acetonitrile, dichloromethane and chloroform). Additionally, the hydrophobic groups covalently bonded to the surface conferred excellent stability to the MoS2/PU material during repeated cycles of oil/water separation, or upon exposure to harsh environments (−20 or +120 °C, acid solution of pH = 1 and base solution of pH = 14, NaCl solution of 3.0%, natural seawater, ethanol and chloroform).

The detection of disease markers is considered an important step for early diagnosis of cancer. We design in this work a novel electrochemical sensing platform for the sensitive and selective detection of folic acid protein (FP). The platform is fabricated by electrophoretic deposition (EPD) of reduced graphene oxide (rGO) onto a gold electrode and post-functionalization of rGO with folic acid. Upon FP binding, a significant current decrease can be measured using differential pulse voltammetry (DPV). Using this scheme, a detection limit of 1pM is achieved. Importantly, the method also allows the detection of FP in serum being thus an appealing approach for the sensitive detection of biomarkers in clinical samples.

Advances in nanotechnology have seen the development of several microbiocidal nanoparticles displaying activity against biofilms. These applications benefit from one or more combinations of the nanoparticle properties. Nanoparticles may indeed concentrate drugs on their surface resulting in polyvalent effects and improved efficacy to fight against bacteria. Nanodiamonds (NDs) are among the most promising new materials for biomedical applications. We elucidate in this paper the effect of menthol modified nanodiamond (ND-menthol) particles on bacterial viability against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. We show that while ND-menthol particles are non-toxic to both pathogens, they show significant antibiofilm activity. The presence of ND-menthol particles reduces biofilm formation more efficiently than free menthol, unmodified oxidized NDs and ampicillin, a commonly used antibiotic. Our findings might be thus a step forward towards the development of alternative non antibiotic based strategies targeting bacterial infections.

The exceptional electrical, thermal, optical and mechanical properties have made two dimensional sp2 hybridized graphene a material of choice in both academic as well as industrial research. In the last few years, researchers have devoted their efforts towards the development of graphene/polymer, graphene/metal nanoparticle and graphene/ceramic nanocomposites. These materials display excellent mechanical, electrical, thermal, catalytic, magnetic and optical properties which cannot be obtained separately from the individual components. Fascinating physical and chemical properties are displayed by noble metal nanomaterials and thus they represent model building blocks for modifying nanoscale structures for diverse applications extending from catalysis, optics to nanomedicine. Insertion of noble metal (Au, Ag) nanoparticles (NPs) into chemically derived graphene is thus of primary importance to open new avenues for both materials in various fields where the specific properties of each material act synergistically to provide hybrid materials with exceptional performances. This review attempts to summarize the different synthetic procedures for the preparation of Ag and Au NPs/reduced graphene oxide (rGO) composites. The synthesis processes of metal NPs/rGO composites are categorised into in-situ and ex-situ techniques. The in-situ approach consists of simultaneous reduction of metal salts and GO to obtain metal NPs/rGO nanocomposite materials, while in the ex-situ process, the metal NPs of desired size and shape are first synthesized and then transferred onto the GO or rGO matrix. The application of the Ag NPs and Au NPs/rGO composite materials in the area of biomedical (drug delivery and photothermal therapy) and biosensing are the focus of this review article.

A sensitive electrochemical active interface for sugar sensing based on the specific boronic acid-diol binding was established. The sensing matrix was formed by stirring a suspension of graphene oxide (GO) with 4-aminophenylboronic acid (APBA). The resulting composite consists of a water insoluble precipitate of reduced graphene oxide (rGO) with APBA incorporated into the rGO matrix. Differential pulse voltammetry (DPV) on glassy carbon electrodes modified with rGO/APBA was used for the detection of fructose, mannose and glucose. The fabricated sensor exhibited a wide linear range with detection limits of 100 nM for fructose, and around 800 nM for mannose and glucose.

a b s t r a c t Conductive diamond nanowires, fabricated by maskless oxygen plasma etching of highly boron-doped polycrystalline diamond substrates, were decorated with nickel nanoparticles. The nickel modified boron- doped diamond nanowire (Ni-BDD NWs) electrodes were prepared through cathodic reduction of nickel sulfate in PBS (pH 6.5) followed by cycling in KOH to oxidize remaining metallic Ni deposits into Ni(OH)2. The novel electrode allowed for orientation-controlled immobilization of histidine-tagged peptides with- out need for surface linking with any other ion-chelating compound. © 2012 Elsevier Ltd. All rights reserved.

One-step metal-assisted electroless chemical etching of silicon substrate was investigated. The etching was performed in aqueous NH 4 F/AgNO 3 /HNO 3 solution at room temperature. The effect of several etching parameters on the morphology of etched layer was studied namely: silicon type, doping level and crystallographic orientation. It is shown that the morphology depends strongly on etching parameters. The reflectivity of the nanostructured layers was examined by reflectance spectroscopy and was found to depend on silicon resistivity. Indeed, the lowest average value of reflectance (a few percent) in the range 250–800 nm was obtained for 5–10 Ω cm p-Si(1 0 0), 0.001–0.003 Ω cm n ++ -Si(1 0 0) and 5–10 Ω cm n-Si(1 0 0). Finally, the dissolution mechanism of silicon by Ag-assisted electroless etching is discussed.

In this paper the fabrication of micrometer long boron-doped diamond nanowire (L-BDD NWs) electrodes is reported. The diamond nanowires were obtained by a maskless reactive ion etching process with oxygen plasma using 15 μm thick polycrystalline boron-doped diamond (BDD) films as starting material. The resulting nanowire interfaces showed enhanced electrochemical activity towards the direct electrochemical detection of glucose under strong basic (pH 12) condition when compared to flat BDD and short nanowires (S-BDD NWs). The robust response of these nanostructures with a detection limit of 60 μM and a linear range up to 8 mM and the ease of formation make L-BDD NWs a promising platform for real time applications. Keywords: Boron-doped diamond, Nanowires, Glucose, Non-enzymatic, Sensing

Thin amorphous silicon (a-Si:H) and carbonated silicon (a-Si1 − xCx:H) layers were deposited on stainless steel substrates using plasma-enhanced chemical vapour deposition (PECVD) in a “low-power” regime. The carbon content of the carbonated silicon (a-Si1 − xCx:H) alloys was varied between 0.1 and 0.37 at.%. The performance of these interfaces as effective corrosion barriers in 3% sodium chloride aqueous solutions was evaluated. Potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) were used next to X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to investigate the protection efficiency of the different barriers. The a-Si:H coated showed better corrosion resistance as compared to the carbonated silicon alloys. No degradation was observed after 14 days immersion of the steel substrate coated with a-Si:H in 3% sodium chloride aqueous solution, making this coating an attractive candidate as corrosion barrier.

International audience; Transparent conductive oxide films are suitable sensitive layers for gas sensors and biosensors, provided that their intrinsic properties are controlled, notably considering their thickness dependence. The present paper reports on a study of the variation of some physical properties of polycrystalline Sb doped SnO2 films according to the film thickness. Films were deposited onto Si and glass substrates by aerosol pyrolysis. Their thickness was varied in a range of 20-280 nm. The electrical resistivity, the roughness, the optical constant, the microstructure and the texture were investigated. Correlated evolutions of the resistivity and the surface roughness are found in relation with the evolutions of both the microstructure and the texture. Two main successive growth steps were evidenced which are delimited by a critical film thickness. Below this thickness of approximately 100-120 nm, a strong dependence of physical properties with the thickness is evidenced whereas for thicker films no significant change is evidenced. A two-step growth model is proposed to explain this behaviour. This mechanism growth is to be considered in view of the integration of SnO2 films as sensitive layers in biosensors. Notably, in the case of biosensors based on the label-free electrochemical detection of biomolecules, it is recommended to use films with thicknesses ranging above the critical thickness value of 100-120 nm in order to obtain optimized, reproducible and comparable responses of biosensors. (c) 2012 Elsevier B.V. All rights reserved.

Surface plasmon resonance (SPR)-based biosensors are very powerful tools for the study of biomolecular interactions, chemical detection and immunoassays. This paper reviews the performance of various SPR structures and detection schemes focusing on propagating surface plasmons generated in planar structures. Some aspects of their surface functionalization, the key element which imparts biofunctionality to these structures and hence transforming them into biosensors, will also be discussed accordingly. The ultimate performance of SPR-based biosensors will thus be determined by both their inherent optical performance and suitable surface functionalization.

Accurate chemical and structural characterization of free-standing zinc oxide (ZnO) and hematite (α-Fe 2 O 3 ) nanorods has been carried out using an AFM/Raman correlative technique under polarized light. ZnO nanorods are found to be wurtzite-type single crystalline objects homogeneous in composition and grown along their principal axis of symmetry. Hematite specimens are rhombohedral corundum-type single crystals grown along a direction orthogonal to their principal axis of symmetry and exhibiting structural disorder. Certain hematite nanorods turn out to be very sensitive to laser heating. These studies reveal the high potential of the coupled AFM/Raman technique to examine the properties of these promising nanomaterials.

Titanium and its alloys are widely used for orthopedic and dental implants because of their superior mechanical properties, low modulus, excellent corrosion resistance and good biocompatibility. However, it takes several months for titanium implants and bone tissue to reach integration. Hence, there is growing interest in shortening the process of osseointegration and thereby reducing surgical restrictions. Various surface modifications have been applied to form a bioactive titanium oxide layer on the metal surface, which is known to accelerate osseointegration. The present work shows that titanium dioxide (TiO2) layers formed on titanium substrates by etching in a solution of sodium hydroxide (NaOH) or hydrogen peroxide/phosphoric acid (H3PO4/H2O2, with a volume ratio of 1:1) are highly suitable pre-treatments for apatite-like coating deposition. Using a two-step procedure (etching in an alkaline or acidic solution followed by soaking in Hanks’ medium), biomimetic calcium phosphate coatings were deposited on porous TiO2 layers. The combined effects of surface topography and chemistry on the formation of the calcium phosphate layer are presented. The topography of the TiO2 layers was characterized using HR-SEM and AFM techniques. The nucleation and growth of calcium phosphate (Ca–P) coatings deposited on TiO2 porous layers from Hanks’ solution was investigated using HR-SEM microscopy. AES, XPS and FTIR surface analytical techniques were used to characterize the titanium dioxide layers before and after deposition of the calcium phosphate coatings, as well as after the process of protein adsorption. To evaluate the potential use of such materials for biomedical applications, the adsorption of serum albumin, the most abundant protein in the blood, was studied on such surfaces.

Hydrophobic thin fluoropolymer films were deposited on carbon steel specimens using inductively coupled radio frequency plasma. Octafluorocyclobutane (C 4 F 8 ) was used as gas source. The anticorrosion resistance of the deposited films in 3% sodium chloride aqueous solution was estimated using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) as well as by electrochemical techniques. Results have shown that a 90 nm fluoropolymer film shows the optimal film thickness in terms of adhesion stability and corrosive resistance. Upon aging in 3% sodium chloride aqueous solutions for a week a decrease of the fluorine concentration together with a layer-by-layer delamination of the polymer coating was observed together with some coating oxidation. A thin polymer film of about 9 nm remained on the steel interface which proved to stay unaltered over a period of a month. This makes the fluoropolymer film interesting as protective layer of metal and metal oxides.

The paper reports on the corrosion behavior of carbon steel coated with thin SiOx-like oxide films. The SiOx-like coatings were deposited by plasma-enhanced chemical vapor deposition (PECVD) and their thickness was varied between 20 and 200 nm. The coated carbon steel interfaces were investigated for their corrosion protection efficiency when immersed in an aqueous saline solution of 3% NaCl. FTIR measurements and electrochemical impedance spectroscopy (EIS) experiments revealed that thin SiOx-like coating layers (20 nm thick) do not prevent the carbon steel from corrosion, while thicker silica layers (d ≥ 100 nm) protect efficiently carbon steel interfaces in highly saline media with a protection efficiency of about 96% for a 200 nm thick coating.

Three systems for photoelectrochemical measurements on the microscale have been implemented and compared: (i) an arrangement in which a fibre illuminates a disc-shaped ultramicroelectrode (UME) face-on; (ii) face-on illumination of a ring UME: and (iii) illumination through a fibre-coupled ring UME assembly. These set-ups have been used to study the classic system in which photoexcited tris(2,2'-bipyridine) ruthenium (II), Ru(bpy)(3)(2+), reduces methyl viologen dication, MV2+, to the radical cation, MV.+. Detection of MV.+ at the UME allows the kinetics to be determined and mass-transport at the various configurations to be assessed. It is shown that face-on illumination of either disc or ring-shaped UMEs can be treated in a straight forward way with simplifications such as a uniform light intensity distribution. On the other hand, while the fibre-coupled ring arrangement is potentially easier and simpler to deploy, it does not appear as amenable to such straightforward treatments. Deviations between experiment and theory in the latter case are attributed to complications such as natural convection and non-uniform light distribution, to which this format appears to be more sensitive. (C) 2010 Elsevier B.V. All rights reserved.

Various oxidation techniques (plasma-beam, sulfo-chromic acid, UV-ozone, heating in air) were applied to single-crystalline (111) and (100) diamond surfaces as well as nanocrystalline diamond (NCD) films and analyzed by X-ray photoelectron spectroscopy (XPS) with respect to oxygen content and type of carbon–oxygen groups formed upon oxidation. Due to their increased surface, NCD films show a significantly higher oxygen uptake as compared to their single-crystal counterparts. No marked differences were observed between the different oxidation techniques. For all oxidation techniques used, several carbon–oxygen groups are simultaneously present on the surface. The relative fraction of singly-oxidized carbon atoms (attributed to isolated ether or epoxy-like groups) generally decreases slightly with increasing oxygen content, but always remains the dominating species.

An ionic liquid (IL, 1-(methylcarboxylic acid)-3-octylimidazolium-bis (trifluoromethylsulfonyl)imide) was covalently coupled onto a boron-doped diamond (BDD) surface through an esterification reaction. The resulting surface was characterized by X-ray photoelectron spectroscopy, water contact angle and electrochemical measurements. Selective electron transfer towards positively and negatively charged redox species was recorded. While the presence of Fe(CN)64− could be detected on the IL-modified BDD interface, no surface-immobilized Ru(NH3)63+ was recorded. The IL-modified BDD electrode showed in addition changes in surface wettability when immersed into aqueous solution containing different anions.

This paper describes a novel platform for preparing localized surface plasmon resonance (LSPR) sensing surfaces. It is based on the coating of gold nanostructures deposited on glass with an amorphous silicon-carbon alloy overcoating. The interest in coating the Au NSs with an amorphous silicon-carbon alloy resides in the possibility of incorporating carboxyl functions directly onto the surface via Si-C covalent bonds. This permits the use of hyrdosilylation reactions to modify the sensor surface. The use of this multilayer structure for the detection of hybridization events is discussed.