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Blood stream infections in the cancer patients are a critical problem which leads to considerable rate of mortality and morbidity. In view of this herein, we account the response of Poly Vinyl Pyrrolidone (PVP) coated silver nanowires (Ag-NWs) and silver nano cubes (Ag-NCs) towards carbapenem (Escherichia coli) and vancomycin (Staphylococcus aureus) resistant strains as well as to human epithelial cells. The prepared PVP capped silver nanomaterials were in the range of 80 nm (Ag-NC) and 25 nm (Ag-NW) as observed from Transmission Electron Microscopy (TEM). Though the selected strains were resistant to carbapenem and vancomycin, PVP capped Ag-NWs and Ag-NCs could inhibit the growth of these strains. These nanomaterials could break the cell wall and damage the genetic material of these strains as observed by death rate assay and alkaline comet assay. Furthermore, we have shown that toxicity of Ag-NWs and Ag-NCs precisely follows the dose retort pattern. Even though the resistant strains were susceptible to a concentration of 10 µg ml−1 of silver nanomaterials the epithelial cells were not affected by the same concentration. It is also confirmed with live dead staining assay and observed that metabolic activities of epithelial cells were not affected by a concentration of 10 µg ml−1. Overall, this work suggests that these nanomaterials can be utilized to treat the multiple drug resistant strains from cancer patients. Keywords: Silver nanomaterials, Multiple drug resistance, Septicaemia, Genotoxicity, Biocompatibility, Cancer

International audience; An effective in situ synthesis strategy is demonstrated for the preparation of silver nanostructures (nanospheres (NSs), nanocubes (NCs), and nanowires (NWs)) on the surface of boron-doped graphene (BG). Further, these functional nanomaterials are employed for the surface-enhanced Raman scattering (SERS) and non-enzymatic electrochemical detection of H2O2. The results confirm the superior performance of BG-Ag nanostructures as SERS platform. Among various geometries of silver nanoparticles studied in this work, we find that the AgNCs over BG (BG-AgNC) present outstanding SERS performance for detecting 4-mercaptobenzoic acid, with a limit of detection of 1.0 × 10–13 M. Furthermore, BG-AgNC exhibits excellent capability to detect melamine as low as 1.0 × 10–9 M. Electrochemical results confirm that the BG-AgNW-based platform exhibits a superior biosensing performance toward H2O2 detection. The enhanced performance is due to the presence of graphene, which improves the conductivity and provides more active sites. The synthesis of doped graphene with metallic nanoparticles described in this work is expected to be a key strategy for the development of an efficient SERS and electrochemical sensor that offers simplicity, cost-effectiveness, long-term stability, and better reproducibility.

Herein we report a simple, one pot and rapid gamma-ray irradiation method for the fabrication of PMMA–Ag nanocomposite films for multifunctional applications. The PMMA–Ag composites were synthesised in situ by dose-dependent gamma-ray irradiation followed by film preparation via a compression moulding technique. The composition of the PMMA polymer and the functional groups were determined using Fourier transform infrared spectroscopy (FT-IR) and Raman analysis while UV-vis spectroscopic and X-ray diffraction (XRD) analysis were used to identify the Surface Plasmon Resonance (SPR) bands and crystallinity of the nanocomposite, respectively. Field emission scanning electron microscopy (FESEM) analysis showed that the particles are spherical with an average particle diameter of ∼35 nm, ∼45 nm, ∼50 nm, ∼65 nm, and ∼75 nm as the irradiation dose was increased from 2–6.5 h while energy dispersive spectroscopy (EDS) analysis confirmed the presence of the corresponding elements. Gel permeation chromatography data were used to determine the molecular weight while contact angle studies revealed the surface properties of the composites. The dielectric properties of the composites were found to increase with an increase in the radiation dose. All the as-synthesised films showed good antimicrobial activity against Gram-positive bacteria, Staphylococcus aureus (S. aureus) and Gram-negative bacteria, Escherichia coli (E. coli). The fabricated PMMA–Ag substrate films allowed the detection of the model probe molecule 4-mercaptobenzoic acid (MBA) at concentrations as low as 10−9 M while the Raman enhancement factor was found to be as high as ∼104.

We present an in-situ polyol assisted synthesis approach for the preparation of silver nanowires (AgNW) over the nitrogen doped graphene (NG) sheets and has been tested as a viable LIBs anode material for the first time. The use of NG serves as nucleation sites, thereby facilitating the growth of AgNWs. The specific material design of the as-prepared NG-AgNW hybrids involves some advantages, including a continuous AgNW-graphene conducting network. Since AgNWs are electrically conductive, it provides an electrical contact with NG sheets which can effectively help the charge transport process and limit the variations in volume during the lithiation/de-lithiation processes. Apart from this, the insertion of metallic Ag nanowires into a percolated NG network increases the interlayer distance of NG sheets and prevent its restacking. Moreover, the more porous nature of the hybrid structure accommodating the large volume changes of AgNWs. As an anode material for LIBs, the NG-AgNW hybrid displays a remarkable initial discharge capacity of 1215 mAh g −1 and attains a stable capacity of 724 mAh g −1 at a current density of 100 mA g −1 after 50 cycles. The electrode exhibits a stable reversible capacity of 714, 634, 550 and 464 mA h g −1 at 0.1, 0.2, 0.5, 1 Ag −1 respectively. The reversible capacity (710 mAh g −1 ) at 0.1 Ag −1 is recovered after the cycling at various current densities confirming outstanding rate performance of the material. In addition, the coulombic efficiency, the NG-AgNW anode retains nearly 99% after the second cycle, further indicating its excellent reversibility. The hybrid material exhibits better cycling stability, greater rate capability, capacity retention and superior reversible capacity than that of bare AgNW and NG sheets. Our smart design will pave way for the development of efficient electrode materials for high capacity and long cycle life LIBs.

We herein report the solvent effects on the aggregation, linear and nonlinear optical properties of silver nanoclusters synthesised using three solvents namely; ethanol, acetone and isopropanol. The Ag clusters were characterized using UV–Visible (UV–vis) and photoluminescence (PL) spectroscopy, Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and open aperture Z-Scan measurements. Density functional theory (DFT) calculations at the B3PW91 level of theory, were done to compute the electric dipole, quadrupole, octapole and hexadecapole moment of mercaptosuccinic acid and mercaptosuccinic acid-Ag 9 cluster in three solvents. Linear optical properties show characteristic absorption profile with quantum confinement at different wavelengths for all the three clusters. The Open aperture Z-scan measurement in Ag clusters establishes the optical limiting properties which arise mostly from excited state absorption (ESA) and relatively weak saturable absorption (SA). The nonlinear optical behaviour varies within the three clusters with maximum optical limiting value obtained for the clusters synthesised using acetone. The theoretically computed hyperpolarizabilities together with z-scan measurements establish the solvent effect on the clusters and their potential applications in optical limiting devices.

Ni-NiO-CNT composite synthesized by swift and simple combustion process is investigated as anode for Li-ion batteries (LIB) and also as an electro-catalyst for oxygen evolution reaction (OER) in alkaline medium. The binder free, electrical conductor less, free standing anode fabricated from Ni-NiO-CNT displays a stable capacity of 736 mAh g−1 at a current density of 200 mAg−1 for the investigated 50 cycles, the exhibited capacity being higher than the theoretical capacity of NiO and carbon. The hybrid composite also exhibits excellent OER activity, achieving current density of 10 mA cm−2 at a lower over potential (η) of 320 mV. The presence of Ni nanoparticles and porous sponge like structure of the composite is the main reason for this high performance. Such multifunctional materials could emerge as promising for realizing future energy storage and conversion approaches.

Gold decorated graphene-based nano-hybrids find extensive research interest due to their enhanced chemical catalytic performance and biochemical sensing. The unique physicochemical properties and the very large surface area makes them propitious platform for the rapid buildouts of science and technology. Graphene serves as an outstanding matrix for anchoring numerous nanomaterials because of its atomically thin 2D morphological features. Herein, we have designed a metal-graphene nano-hybrid through pulsed laser ablation. Commercially available graphite powder was employed for the preparation of graphene oxide (GO) using modified Hummers&rsquo, method. A solid, thin gold (Au) foil was ablated in an aqueous suspension of GO using second harmonic wavelength (532 nm) of the Nd:YAG laser for immediate generation of the Au-GO nano-hybrid. The synthesis strategy employed here does not entail any detrimental chemical reagents and hence avoids the inclusion of reagent byproducts to the reaction mixture, toxicity, and environmental or chemical contamination. Optical and morphological characterizations were performed to substantiate the successful anchoring of Au nanoparticles (Au NPs) on the GO sheets. Remarkably, these photon-generated nano-hybrids can act as an excellent surface enhanced Raman spectroscopy (SERS) platform for the sensing/detection of the 4-mercaptobenzoic acid (4-MBA) with a very low detection limit of 1 &times, 10&minus, 12 M and preserves better reproducibility also. In addition, these hybrid materials were found to act as an effective catalyst for the reduction of 4-nitrophenol (4-NP). Thus, this is a rapid, mild, efficient and green synthesis approach for the fabrication of active organometallic sensors and catalysts.

International audience; Hetero atom doped graphene - metal nanoparticle hybrids have received increasing attention owing to their unique electronic properties, large specific surface area, very high conductivity and more electronic interactions. Herein, we report for the first time a hydrothermal assisted strategy for developing novel class of nitrogen (N) and sulfur (S) co-doped graphene/Ag nano morphotypes (sphere, cube and wire) hybrids for enhanced optical limiting (OL) and surface-enhanced Raman scattering (SERS) applications. Two probe molecules, Rhodamine 6G and para-aminothiophenol, are chosen to determine the enhancement performance of the as-prepared SERS-active substrate. Our results signified that the Ag nanocube-N, S codoped graphene hybrid based SERS-active substrate presents excellent performances for sensing R6G with an enhancement factor of 1.07 × 107. Further, this SERS substrate reveals outstanding capability to detect P-ATP molecules with detection limit of approximately 1.0 × 10−12 M. Moreover, the non-linear optical absorption studies results show that the OL properties were appreciably enhanced after the insertion of Ag nanostructures on the NSG surface. Thus, OL properties of the two-dimensional N, S-codoped graphene can be effectively modified by absorbing AgNPs of different morphology on its surface. All of the results signify that these hybrid structures will show extended applications for SERS sensing and optoelectronic fields.

Optical properties are among the most entrancing and helpful properties of nanomaterials and have been widely examined utilizing an assortment of optical spectroscopic strategies. Here, we present a detailed discussion covering the optical properties of metal nanoparticles, semiconductor nanoparticles, semiconductor quantum dots, metallic clusters, and carbon-based materials. It covers UV-Vis absorption and the photoluminescence (PL) properties, their control, and origins in various nanoparticles. Different mechanisms in which nanostructures exhibit PL are discussed. The optical-related applications of nanoparticles are explained in a detailed manner. We have critically analyzed the surface-enhanced Raman scattering and nonlinear optical limiting properties of different types of nanostructures.

Synthesis and characterization of nanomaterials plays a crucial role in material science and engineering. Nanoparticles exist in a number of shapes depending upon the synthesis procedures. Nanostructured materials showing different morphologies such as nanoparticles, nanotubes, nanowires, nanoflowers, nanocubes, etc. have been extensively studied and have shown considerable technological value in many applications. Morphological control in nanomaterials has a lot of significance, because of its striking properties from microscopic probes to nanoelectronic systems. These functional nanomaterials ensure the possibility of fabricating devices in the area of optics, electronics, magnetism, and photonics. Different shapes of nanomaterials include nanospheres, nanocube, nanowires, nanoreef, nanoclusters, and nanotubes. Microstructural characterization gives information about the morphology of different phases, number of phases, chemical composition, and crystallographic defects. Various properties of nanomaterials can be finely tuned based on its morphology, therefore a detailed study on the morphology of nanomaterials and its effect on the optical, electrical, magnetic, electronic, and thermal properties is required. Various morphological characterization techniques such as atomic force microscope, scanning electron microscope, transmission electron microscope, etc. were used to evaluate the particles in the nanoregime.

Metal nanowires exhibit unusually high catalytic activity towards oxygen reduction reaction (ORR) due to their inherent electronic structures. However, controllable synthesis of stable nanowires still remains as a daunting challenge. Herein, we report the in situ synthesis of silver nanowires (AgNWs) over boron doped graphene sheets (BG) and demonstrated its efficient electrocatalytic activity towards ORR for the first time. The electrocatalytic ORR efficacy of BG-AgNW is studied using various voltammetric techniques. The BG wrapped AgNWs shows excellent ORR activity, with very high onset potential and current density and it followed four electron transfer mechanism with high methanol tolerance and stability towards ORR. The results are comparable to the commercially available 20% Pt/C in terms of performance.