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Silver nanoparticles (Ag NPs) were successfully synthesized using AgNO 3 via an eco-friendly and simple green route using Abelmoschus esculentus (L.) pulp extract at room temperature. The phytochemicals present in A. esculentus (L.) pulp extract were used both as a reducing and a stabilizing agent for the synthesis of Ag NPs. The stabilization of Ag NPs with phytochemicals was justified using Fourier-transform infrared spectroscopy. The size of the as-synthesized Ag NPs was examined using dynamic light scattering and confirmed by transmission electron microscopy. The crystalline nature of Ag NPs had been identified using X-ray diffraction. The present study demonstrated the efficacy of Ag NPs against Jurkat cells in vitro. Our study also showed that the IC 50 dose of Ag NPs leads to the increase in intracellular reactive oxygen species and significantly diminished mitochondrial membrane potential, indicating the effective involvement of apoptosis in cell death. The synthesized Ag NPs also exhibited good antimicrobial activity against different gram class bacteria. [ABSTRACT FROM AUTHOR]

The work deals with an environmentally benign process for the synthesis of silver nanoparticle using Butea monosperma bark extract which is used both as a reducing as well as capping agent at room temperature. The reaction mixture turned brownish yellow after about 24 h and an intense surface plasmon resonance (SPR) band at around 424 nm clearly indicates the formation of silver nanoparticles. Fourier transform-Infrared (FT-IR) spectroscopy showed that the nanoparticles were capped with compounds present in the plant extract. Formation of crystalline fcc silver nanoparticles is analysed by XRD data and the SAED pattern obtained also confirms the crystalline behaviour of the Ag nanoparticles. The size and morphology of these nanoparticles were studied using High Resolution Transmission Electron Microscopy (HRTEM) which showed that the nanoparticles had an average dimension of ∼35 nm. A larger DLS data of ∼98 nm shows the presence of the stabilizer on the nanoparticles surface. The bio-synthesized silver nanoparticles revealed potent antibacterial activity against human bacteria of both Gram types. In addition these biologically synthesized nanoparticles also proved to exhibit excellent cytotoxic effect on human myeloid leukemia cell line, KG-1A with IC 50 value of 11.47 μg/mL. [ABSTRACT FROM AUTHOR]

Bile salts carry out a vital bioactive responsibility among the various physiologically important molecules. The use of bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects and gives rise to various versatile properties. Sodium cholate, a biosurfactant which is environmentally safe, has been used to reduce and stabilize silver nitrate solution. The silver nanostructures thus produced are crystalline and anisotropic in nature and show different types of particle shapes and sizes depending on the reaction conditions including star and wire shapes which have not been reported earlier, by simply varying the reaction conditions. The silver precursor concentration and the ratio of sodium cholate to silver precursor were the key factors which controlled the morphosynthesis. The formation of the silver NPs was monitored using UV-vis spectrophotometry. The transmission electron microscopy (TEM) technique was used to study the morphology of the synthesized NPs. Fourier transform infrared (FT-IR) spectroscopy was used to identify the interaction of sodium cholate with the synthesized NP. The possible mechanistic role of sodium cholate in the reduction and stabilization of silver nanoparticles (Ag NPs) has also been discussed. The obtained Ag NPs exhibit antibacterial and anticancerous activities. The present study also explores the cytotoxic role of Ag NPs in KG-1A (human acute myeloid leukemia) and K562 (human chronic myeloid leukemia) cell lines. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI)-Ag nanocomposites were synthesized by in situ chemical polymerization approach using ammonium persulfate and silver nitrate as oxidant. Characterizations of nanocomposites were done by ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). UV-vis, XRD and FTIR analysis established the formation of PANI/Ag nanocomposites and face-centered-cubic phase of silver. PANInanofibers were of average diameter ∼ 30 nm and several micrometers in length. Morphological analysis showed that the spherical-shaped silver nanoparticles decorate the surface of PANI nanofibers. Silver nanoparticles of average diameter ∼ 5-10 nm were observed on the TEM images for the PANI-Ag nanocomposites. Such type of PANI-Ag nanocomposites can be used as bistable switches as well as memory devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Silver nanoparticles were successfully synthesized from AgNO3through a reliable, eco-friendly and simple green route usingPaederia foetida L.leaf extract as a reducing cum stabilizing agent. UV-Visible Spectroscopy, dynamic light scattering, atomic force microscopy, transmission electron microscopy, and X-ray diffraction analysis were used for characterization of silver nanoparticles. The synthesized silver nanoparticles were spherical in shape with size range of 4–15 nm. The nanoparticles were face-centered cubic crystal structure. The adopted technique for silver nanoparticle synthesis is suitable for large-scale production. The as-prepared silver nanoparticles revealed excellent antibacterial activity against different gram classes of bacteria and would be a promising candidate for various pharmaceutical, biomedical, and environmental applications. [ABSTRACT FROM PUBLISHER]

In recent years, rapid technological advancements have led to the development of nanoscale device components, advanced sensors, and novel biomimetic materials. Potential negative impacts of nanomaterials are sometimes overlooked during the discovery phase of research. The use of green chemistry can however enhance nanoscience by maximizing safety and efficiency while minimizing the environmental and societal impacts of nanomaterials. Here we report extracellular mycosynthesis of silver nanoparticles by Alternaria alternata. The fungal biomass when exposed to aqueous silver nitrate solution leads to the formation of silver nanoparticles extracellularly. Change in colour of silver nitrate solution to brown signifies the development of silver nanoparticles. UV-Visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Agglomeration status was confirmed by Dynamic Light Scattering experiments. Atomic Force Microscopy and Transmission Electron Microscopy explained the formation of well-dispersed silver nanoparticles in the range of 20-45 nm. X-ray Diffraction spectrum of the silver nanoparticles exhibited 20 values corresponding to the silver nanoparticles. Fourier Transform Infrared Spectroscopy confirmed the presence of a protein shell outside the nanoparticles. In this study, mycosynthesized nanoparticles were also evaluated for DNA damaging potential in human lymphocytes using comet assay. [ABSTRACT FROM AUTHOR]

In this work, harvested mushroom substrate (HMS) has been explored for the first time through a comprehensive optimization study for the green synthesis of silver nanoparticles (AgNPs). A multiple response central composite design with three parameters: pH of the reaction mixture, temperature, and incubation period at three distinct levels was employed in the optimization study. The particle size of AgNPs, UV absorbance, and the percentage of Ag/Cl elemental ratio were considered as the response parameters. For each response variable examined the model used was found to be significant (P < 0.05). The ideal conditions were: pH 8.9, a temperature of 59.4 °C, and an incubation period of 48.5 h. The UV–visible spectra of AgNPs indicated that the absorption maxima for AgNP–3 were 414 nm, 420 for AgNPs–2, and 457 for AgNPs-1. The XRD analysis of AgNPs-3 and AgNPs-2 show a large diffraction peak at ∼38.2°, ∼44.2°, ∼64.4°, and ∼77.4°, respectively, which relate to the planes of polycrystalline face-centered cubic (fcc) silver. Additionally, the XRD result of AgNPs–1, reveals diffraction characteristics of AgCl planes (111, 200, 220, 311, 222, and 400). The TEM investigations indicated that the smallest particles were synthesized at pH 9 with average diameters of 35 ± 6 nm (AgNPs–3). The zeta potentials of the AgNPs are −36 (AgNPs–3), −28 (AgNPs–2), and −19 (AgNPs–1) mV, respectively. The distinct IR peak at 3400, 1634, and 1383 cm−1 indicated the typical vibration of phenols, proteins, and alkaloids, respectively. The AgNPs were further evaluated against gram (+) strain Bacillus subtilis (MTCC 736) and gram (−) strain Escherichia coli (MTCC 68). All of the NPs tested positive for antibacterial activity against both bacterial strains. The study makes a sustainable alternative to disposing of HMS to achieve the Sustainable Development Goals (SDGs). [Display omitted] • Harvested Mushroom Substrate utilized for the synthesis of silver nanoparticles. • The synthesis process was further optimized with central composite design. • PH > 9 yielded better morphology of synthesized silver nanoparticles. • The average size of the silver nanoparticles at pH > 9 was 35 ± 6 nm. • Highest bactericidal activity of silver nanoparticles were observed in 6.96 ± 0.03 ppm. [ABSTRACT FROM AUTHOR]

Resorcinol based reduction and capping of ultra-small colloidal silver nanoparticles (Ag NPs) optimally formed hydrogen bond driven clusters within the water-based solution. Large-area self-assembled fractal structures of Ag NPs aggregates were fabricated by solvent evaporation technique on silicon substrate. The final dried surface structures were found to be pH dependent which was adjusted to particular values after the optimal reduction of silver salt, capping of Ag NPs, followed by cluster formation at an optimum pH in the solution phase. These self-assembled surface structures show controlled enhancement of various surface optical phenomena such as Raman spectra of a model dye and luminescence of Ag NPs as a function of pH dependent fractal dimension of the resulting structures. The structure, morphology and various relevant optical properties of self-assembled fractals of Ag NPs were further established by combined use of X-Ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV-Visible, photoluminescence and Raman spectroscopy analysis. Image 1 • Ag NPs were synthesized using resorcinol as reducing and capping agent and was found to be luminescent. • SPR show peaks at 353 and ~500 nm and their PL emission was observed at 411 nm and 544 nm respectively. • Fractal dimension (F D) was calculated to be 1.89 which decreases to ~1.6 with pH variation in acidic and basic. • R6G was used as probe molecules for SERS measurements which verified that the substrate has high sensitivity to SERS response. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ag@Ag 2 S core shell nanoparticles were synthesized by soft chemical route. • SPR of Ag NPs blue shifts from 408 to 378 nm with increasing sulfur ion concentration. • Ag@Ag 2 S CSNPs exhibit tunable (1.43–1.50 eV) NIR luminescence with increasing sulfur ion concentration. Abstract Ag-Ag 2 S core-shell nano-structured particles, prepared by soft chemical route, were found to be luminescent in the near-infrared (NIR) range. The silver nanoparticles were pre-synthesized with size control by poly-vinyl-pyrrolidone (PVP) polymer capping from silver nitrate solution, by reduction using sodium borohydride in solution, which were further subjected to reaction with sulfur ions in the later stage by mixing controlled amount of Na 2 S in the solution. With increasing concentration of sulfur ions, the plasmonic peak of Ag showed progressive blue shift and damping, leading to final diminishment. Enhanced NIR luminescence obtained from Ag@Ag 2 S core-shell nanoparticles were found to be asymmetric and blue shifting with reduced intensity and increasing sulfur ion concentration. The mechanism behind such a behavior is predicted due to formation of composite layer of Ag 2 S-Ag both at the surface and the volume, with Ag core at the center, diminishing in size with increasing sulfur concentration. The structure, chemical composition, morphology and final core-shell structure formation were further established by combination of X-ray diffractometry (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) analysis. [ABSTRACT FROM AUTHOR]

A facile one-pot approach for rapid synthesis of silver and gold nanoparticles (Ag NPs and Au NPs) with narrow size distribution and good stability was described by reducing silver nitrate and chloroauric acid with polysaccharide dextrin. Here, dextrin was used as both a reducing and stabilizing agent for synthesis of NPs. The as-synthesized Ag NPs and Au NPs were characterized by UV–visible absorption spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The Ag NPs and Au NPs exhibited an absorption maxima at 404 and 547 nm respectively. TEM images showed NPs in the range of 8–28 nm. The crystallinity of the NPs was measured by XRD analysis. Furthermore, the as-prepared Ag NPs revealed colorimetric sensor property for detection of Cu 2+ ions based on changes in absorbance resulting from metal ion-induced aggregation of NPs or direct deposition of metal ions onto NPs. The as-prepared Au NPs exhibited a notable catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH 4 . [ABSTRACT FROM AUTHOR]

Abstract: In this paper we reported preparation of methylcellulose–silver nanocomposite films by mixing of aqueous solution of methylcellulose with silver nitrate followed by casting. The silver nanoparticles were generated in methylcellulose matrix through reduction and stabilization by methylcellulose. The surface plasmon band at 412nm indicated the formation of Ag nanoparticles. The MC–Ag nanocomposite films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). The X-ray diffraction analysis of synthesized MC–Ag nanocomposite films revealed that metallic silver was present in face centered cubic crystal structure. Average crystallite size of silver nanocrystal was 22.7nm. The FTIR peaks of as-synthesized MC–Ag nanocomposite fully designated the strong interaction between Ag nanoparticles and MC matrix. Nano-sized silver modified methylcellulose showed enhanced mechanical properties i.e. the introduction of Ag leading to both strengthening and toughening of MC matrix. The methylcellulose–silver nanocomposite films offered excellent antimicrobial activity against various microorganisms. [Copyright &y& Elsevier]