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This study presents a comprehensive exploration of the electrochemical behavior of layer‐by‐layer assemblies comprising silver nanoparticles (AgNPs), poly‐l‐lysine (PLL), and bovine serum albumin (BSA) on gold surfaces. AgNPs were synthesized using the reduction of silver ions with the synergy of ascorbic acid and citrate in the presence of sodium chloride. The obtained silver nanoparticles were characterized using transmission electron microscopy, dynamic light scattering and UV‐Vis spectroscopy. A typical preparation produced AgNPs with a plasmon peak at 402 nm, a diameter of 27.5 nm and zeta potential of −37 mV. Employing a drop‐coating approach, we successfully achieved stable multilayers of AgNPs, PLL, and BSA. Cyclic voltammetry revealed well‐defined, bell‐shaped oxidation and reduction peaks of AgNPs within the multilayers, demonstrating complete conversion to AgCl and back to Ag. Notably, the stripping of AgNPs on a monolayer of PLL prepared at pH 4.00 resulted in the highest current intensity, contrasting with lower intensities observed for PLL monolayers prepared at pH 7.01 and pH 9.01. Despite the absence of a splitting reduction peak in the presence of biopolymer materials, a noteworthy observation emerged: the peak splitting exclusively occurred when PLL/AgNP layers, terminated with PLL, were exposed to BSA in the solution. [ABSTRACT FROM AUTHOR]

Herein, silver ions modified α-Fe2O3 (Ag: α-Fe2O3) nanoparticles were synthesized using a sol-gel auto-combustion method comprising of dual phase i.e. trigonal structure of α-Fe2O3 and FCC structure of Ag. The refinement results verified the existence of both the phase with R-3c: R s and Fm-3 m space group. Transmission Electron Microscopy (TEM) showed the crystallite size around 34.24 ± 2.00 nm. The percentage of Ag0 and Ag+ verified through X-ray Photoelectron Spectroscopy (XPS) clearly indicate that around 74% of the Ag present is in the metallic form. The cyclic voltammetry showed that the Csp of the Ag: α-Fe2O3 NPs modified electrode is 132 Fg − 1 and 100 Fg − 1 when recorded at a scan rate of 50 mVs− 1 and 75 mVs− 1, respectively. The Zones of Inhibition (ZOI) against bacterial strains generated by utilizing Ag: α-Fe2O3 NPs are clearly showed the ZOI of 19 ± 1 mm against Bacillus subtilis. The synthesized nanoparticles exhibited higher inhibition against the bacterial strains in comparison to the standard antibiotic ampicillin. Further, cell viability analysis suggested to use a concentration of 9 to 12 µg/ml for Ag: α-Fe2O3in invitro experiments. [ABSTRACT FROM AUTHOR]

This study explores the potential of zinc and silver nanocomposites, synthesized with β-lactoglobulin, a whey protein, in promoting wound healing, using the C57BL/6J mouse model. Our research is distinct in its dual focus: assessing the antimicrobial efficacy of these nanocomposites and their impact on wound healing processes. The antimicrobial properties were investigated through minimum inhibitory concentration (MIC) assessments and colony-forming unit (CFU) tests, providing insights into their effectiveness against wound-associated microorganisms. Notably, the formulation's effective antibacterial concentration did not exhibit toxicity to mouse fibroblasts. A key aspect of our methodology involved the use of a stereoscopic microscope for detailed monitoring of the wound closure process. Additionally, the distribution and potential systemic effects of the zinc and silver ions were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). This analysis was crucial in evaluating metal ion absorption through the wound site and estimating any toxic effects on the body. Our findings are particularly significant in the field of regenerative medicine. Transmission electron microscopy (TEM) revealed that the tested nanocomposites notably enhanced collagen deposition, a vital component in the wound healing process. Furthermore, a reduction in glycogen levels in hepatocytes was observed following treatment with these metal-protein dressings. This novel finding warrants further investigation. Overall, our findings highlight the diverse roles of zinc and silver nanocomposites in wound healing. This study not only contributes to our understanding of metal-protein complexes in tissue regeneration but also opens new avenues for research into the delivery mechanisms of such treatments for hard-to-heal wounds. [ABSTRACT FROM AUTHOR]

To investigate the mechanism of Triton X-100 (TX-100) reducing the Ag+-resistance of Enterococcus faecalis (E. faecalis), and evaluate the antibacterial effect of TX-100 + Ag+ against the induced Ag+-resistant E. faecalis (AREf). The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of AgNO3 against E. faecalis with/without TX-100 were determined to verify the enhanced antibacterial activity. Transmission electron microscopy (TEM) was used to observe the morphological changes of E. faecalis after treatment. The intra- and extracellular concentration of Ag+ in treated E. faecalis was evaluated using inductively coupled plasma mass spectrometer (ICP-MS). The changes in cell membrane potential and integrity of treated E. faecalis were also observed using the flow cytometer. Moreover, AREf was induced through continuous exposure to sub-MIC of Ag+ and the antibacterial effect of TX-100 + Ag+ on AREf was further evaluated. The addition of 0.04% TX-100 showed maximal enhanced antibacterial effect of Ag+ against E. faecalis. The TEM and ICP-MS results demonstrated that TX-100 could facilitate Ag+ to enter E. faecalis through changing the membrane structure and integrity. Flow cytometry further showed the effect of TX-100 on membrane potential and permeability of E. faecalis. In addition, the enhanced antibacterial effect of TX-100 + Ag+ was also confirmed on induced AREf. TX-100 can facilitate Ag+ to enter E. faecalis through disrupting the membrane structure and changing the membrane potential and permeability, thus reducing the Ag+-resistance of E. faecalis and enhancing the antibacterial effect against either normal E. faecalis or induced AREf. [ABSTRACT FROM AUTHOR]

The preparation of ultra–small silver nanoparticles (average diameter ≤10 nm) is a technical problem because of their aggregation tendency. Therefore, the preparation conditions are usually harsh and complex. It is widely recognized that covalent organic frameworks (COFs) represent a novel class of porous crystalline compounds with broad applications in various fields. In this work, an environmentally and economically friendly new method has been developed for synthesizing ultra–small silver nanoparticles by reducing silver ions in ethanol solution with a covalent organic framework (TPB–DMTP–COF) as a template and reductant at room temperature. Interestingly, the TPB–DMTP–COF not only serves as a template and reductant but also functions as a stabilizer. Moreover, the TPB–DMTP–COF can be utilized repeatedly as a reductant. The morphology and structure of the silver nanoparticles were examined using transmission electron microscopy and showed that they were spherical with an average particle size of approximately 7.5 nm. Compared with the previously reported silver nanoparticles, the silver nanoparticles synthesized by this new method are not coated with Surfactant, such as Polyvinylpyrrolidone (PVP). As a result, they possess a larger exposed surface area, exhibit increased activity, and demonstrate excellent antimicrobial properties against both Gram–negative Escherichia coli and Gram–positive bacteria Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Herein we present the results of optimization of silver nanoparticles biosynthesis using a nonpathogenic soil bacterium Azospirillum brasilense. The conditions and parameters for synthesis of biogenic nanoparticles using A. brasilense vegetative cells, culture liquid, and homogeneous polyphenol oxidase preparations were analyzed. We have revealed the ranging effect of the incubation time, the concentration of silver ions, pH of the reaction mixture, and the concentration of metabolites, towards the production of colloidal silver nanoparticles with specified geometric parameters, high colloidal stability and relatively good monodispersity. The size, shape, and relative yield of electron-dense nanostructures were determined by transmission electron microscopy and dynamic light scattering; extinction spectra were recorded by UV-vis spectrophotometry. [ABSTRACT FROM AUTHOR]

The aim of this work was to propose a simple method for synthesizing differently shaped AgNPs and to find a suitable stabilizing/capping agent to ensure the non-toxicity of AgNPs. Using a chemical method, by simply changing the volume of reducing agents, we successfully prepared colloids of differently shaped AgNPs (spherical (~10 nm), triangular (~40 nm), rodlike (~30 nm), and a mixture of these shapes). The nanoparticle sizes and shapes affect the solution color. UV-VIS spectroscopy was used to evaluate the colloidal solutions, and transmission electron microscopy was used to analyze the shape and size of the nanoparticles. To create non-toxic and stable AgNPs, it is necessary to modify the surface properties of the nanoparticles; one possibility is to create a biocompatible layer on the nanoparticle surface. We successfully applied a combination of trisodium citrate and polyvinylpyrrolidone, thereby preventing the release of silver ions, which are responsible for the toxic effects of AgNPs. The synthesized nanoparticles show very low, mostly negligible antibiofilm activity against the green algae Chlorella kessleri. AgNPs were used to prepare polymer-AgNP composite thin layers and fibers. It was proved that AgNPs can influence polymer matrix properties. [ABSTRACT FROM AUTHOR]

Background: Atropa acuminata plant, which is also known as the maitbrand or Indian belladonna, belongs to the family Solanaceae and is closely related to the deadly nightshade of Europe and North Africa used in the treatment of various diseases. Objectives: The main objective is to investigate the antidiabetic potential of silver nanoparticles of Atropa acuminata. Methods: In this study green synthesis of silver nanoparticles was carried out. The current study engross the green synthesis of A. acuminata roots by reducing silver ions, where ultraviolet (UV) spectral analysis and transmission electron microscopy confirmed nanoarchitecture. The optimized silver nanoparticles were characterized for shape, size and morphological features by various techniques viz., SEM, TEM EDXA and XRD. The optimized formulation was further subjected for lipid peroxidation assay and in vitro antidiabetic assay in order to understand the antidiabetic potential of formulated silver nanoparticles. Results: The Silver nanoparticles of Atropa acuminata roots was successfully prepared by optimizing different concentration of plant extract at different temperatures and stirring speed. The Resultant optimized nanoparticles showed a particle size around 20 nm and -28 mv zeta potential. Further the characterization of optimized AgNPs was carried out. SEM provides the shape, size, and morphological features, whereas EDXA confirms the compositions and distribution of nanoparticles through spectrum and elemental mapping. XRD diffraction analysis revealed the crystalline structure of nanoparticles. Further, Nanoparticles showed a maximum scavenging potential of 82.633±0.116 for superoxide anion free radicals at 100 µg/mL concentration. Among two anti-diabetic assays, the α amylase assay shows a better result of percent inhibition 63 ± 1.32 at 75 µg/ml concentrations. Lastly, in vitro, drug release study revealed a 101.50% cumulative release from Ag-NPs formulation up to 1 hour, which was better than the standard one. Conclusion: This study explores the novel technology of green synthesis for various biomedical applications. [ABSTRACT FROM AUTHOR]

Bacterial biofilms are a significant problem in the food industry, as they are difficult to eradicate and represent a threat to consumer health. Currently, nanoparticles as an alternative to traditional chemical disinfectants have garnered much attention due to their broad-spectrum antibacterial activity and low toxicity. In this study, silver nanoparticles (AgNPs) were synthesized by a biological method using a Jacaranda mimosifolia flower aqueous extract and by a chemical method, and the factors affecting both syntheses were optimized. The nanoparticles were characterized by Ultraviolet–visible (UV–Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), Dynamic light scattering (DLS), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) with a spherical and uniform shape. The antibacterial and antibiofilm formation activity was carried out on bacterial species of Pseudomonas aeruginosa and Staphylococcus aureus with the capacity to form biofilm. The minimum inhibitory concentration was 117.5 μg/mL for the chemical and 5.3 μg/mL for the biological nanoparticles. Both types of nanoparticles showed antibiofilm activity in the qualitative Congo red test and in the quantitative microplate test. Antibiofilm activity tests on fresh lettuce showed that biological nanoparticles decreased the population of S. aureus and P. aeruginosa by 0.63 and 2.38 logarithms, respectively, while chemical nanoparticles had little microbial reduction. In conclusion, the biologically synthesized nanoparticles showed greater antibiofilm activity. Therefore, these results suggest their potential application in the formulation of sanitizing products for the food and healthcare industries. [ABSTRACT FROM AUTHOR]

The application of green synthesis for silver nanoparticles in nanomedicine has experienced significant growth. Strobilanthes glutinosus, a plant primarily located in the Himalayas, remains largely unexplored. Considering the biomedical value of S. glutinosus, phytochemicals from this plant were used for the biosynthesis of silver nanoparticles. Silver nanoparticles were synthesized from aqueous extract of root and leaves of Strobilanthes glutinosus. The synthesized silver nanoparticles were characterized using UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction. Total phenolic and flavonoid contents of plants were determined and compared with nanoparticles. The biomedical efficacy of plant extracts and silver nanoparticles was assessed using antioxidant and antibacterial assays. The UV–Vis spectra of leaf- and root-extract-mediated AgNPs showed characteristic peaks at 428 nm and 429 nm, respectively. TEM images revealed the polycrystalline and spherical shapes of leaf- and root-extract-mediated AgNPs with size ranges of 15–60 nm and 20–52 nm, respectively. FTIR findings shown the involvement of phytochemicals of root and leaf extracts in the reduction of silver ions into silver nanoparticles. The crystalline face-centered cubic structure of nanoparticles is depicted by the XRD spectra of leaf and root AgNPs. The plant has an ample amount of total phenolic content (TPC) and total flavonoid content (TFC), which enhance the scavenging activity of plant samples and their respective AgNPs. Leaf and root AgNPs have also shown good antibacterial activity, which may enhance the medicinal value of AgNPs. [ABSTRACT FROM AUTHOR]

Green synthesis of silver nanoparticles (AgNPs) using the Alysicarpus vaginalis alcoholic extract as a reducing agent and a capping ligand was carried out. Notable peaks of λmax 442–602 nm indicated the reduction of silver ions to elemental AgNPs. Particle size (Zavg) was in the range of 32.3±0.76 to 252.3±0.342 nm). The negative Zeta potential (ZP, −2.9±0.31 to −21.7±0.13 mV) and low polydispersity index (PDI, 0.181±0.02 to 0.635±0.02) supported the homogeneous nature of AgNPs. Further, crystalline spherical nature of AgNPs with a smooth surface was confirmed by high‐resolution transmission electron microscopy (HRTEM) studies. The AgNPs showed 1.2 to 1.4‐fold enhanced antibacterial activity than extract (6–10 mm zone of inhibition) against Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes, and Salmonella enterica ser. Typhi by disc diffusion assay. The AgNP formulation F9 showed equal (against Gram‐positive L. monocytogenes) or even better (against Gram‐negative S. enterica Typhi) antimicrobial activity than the positive control, ciprofloxacin. Further investigations on F9 are suggested in order to develop a broad‐spectrum, cost‐effective antibacterial formulation of natural origin. This study represents a significant step forward in the field of bio‐fabrication and presents a promising alternative to traditional chemical synthesis methods for the production of antimicrobial AgNPs. [ABSTRACT FROM AUTHOR]

In this work, the smashing effect of explosives innovatively led to the preparation of nanoparticles. The energetic material 3,5-dinitrobenzoic acid (DNBA) was introduced as a ligand to coordinate with silver ions and connect graphene sheets via electrostatic attraction in the sol–gel process. Owing to the thermolysis of DNBA, the pore-formation of graphene sheets, thermal reduction of Ag+ and achievement of monodisperse Ag nanoparticles were realized simultaneously. The morphology and composition of the nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Then, the nanocomposite was used to construct a hydrogen peroxide (H2O2) sensor, which displayed excellent catalytic performance over a wide linear concentration range of 4 × 10−5 to 4 × 10−3 mM with a corresponding sensitivity of 72 μA mM−1 cm−2 and detection limit of 101.25 nM with a signal-to-noise ratio of 3. [ABSTRACT FROM AUTHOR]

In this work, the smashing effect of explosives innovatively led to the preparation of nanoparticles. The energetic material 3,5-dinitrobenzoic acid (DNBA) was introduced as a ligand to coordinate with silver ions and connect graphene sheets via electrostatic attraction in the sol–gel process. Owing to the thermolysis of DNBA, the pore-formation of graphene sheets, thermal reduction of Ag+ and achievement of monodisperse Ag nanoparticles were realized simultaneously. The morphology and composition of the nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Then, the nanocomposite was used to construct a hydrogen peroxide (H2O2) sensor, which displayed excellent catalytic performance over a wide linear concentration range of 4 × 10−5 to 4 × 10−3 mM with a corresponding sensitivity of 72 μA mM−1 cm−2 and detection limit of 101.25 nM with a signal-to-noise ratio of 3. [ABSTRACT FROM AUTHOR]

In this work, the preparation, characterization, and application of Fe3O4-polyindole-Ag composite are reported. The Fe3O4-PIN-Ag composite with the structure that Ag nanoparticles were decorated on the surface of Fe3O4-PIN was prepared via a facile in situ method. The nanocomposite was manufactured via oxidation in situ polymerization of indole on iron oxide nanoparticles in the presence of ammonium persulfate, (NH4)2S2O8, as an oxidant. Then, the formed silver nanoparticles without using external reductant were deposited on the surface of polyindole. The structure and the component of Fe3O4-PIN-Ag composite were well identified by FT-IR, UV–Vis, XRD, SEM, EDX, ICP-AES, and TEM techniques. The composites indicated excellent catalytic activities for the reduction of 4-nitrophenol and methylene blue in the presence of NaBH4 and removal of methylene blue with just a low amount of adsorbent (1 mg). The catalyst could complete reduction of 4-nitrophenol and methylene blue in 28 and 20 min, respectively, and adsorption of methylene blue in 140 min with apparent rate constants kapp of 9.49 × 10–2, 16 × 10–2, and 1.2 × 10–2 min−1, respectively. The Fe3O4-PIN-Ag composite was able to capture the electrons/hydride ions and increased the opportunities to reduce 4-nitrophenol and methylene blue and could help to facilitate the contact of methylene blue by PIN chains and Ag nanoparticles. This catalyst exhibited superior durable catalytic stability so that no significant activity loss was observed in the consecutive six reaction runs. [ABSTRACT FROM AUTHOR]

Near surface silver nanoparticles embedded in silicon oxide were obtained by 40 keV silver negative ion implantation without the requirement of an annealing step. Ion beam induced local heating within the film leads to an exodiffusion of the silver ions towards the film surface, resulting in the protrusion of larger nanoparticles. Cross-sectional transmission electron microscopy reveals the presence of poly-disperse nanoparticles (NPs), ranging between 2 nm and 20 nm, at different depths of the SiO2 film. The normal incidence reflectance spectrum shows a double kink feature in the vicinity of 400 nm, indicating a strong localized surface plasmon resonance (LSPR) from the embedded NPs. However, due to overlap of the bilayer interference and LSPR, the related features are difficult to separate. The ambiguity in associating the correct kink with the LSPR related absorption is cleared with the use of transfer matrix simulations in combination with an effective medium approximation. The simulations are further verified with angle dependent reflectance measurements. Additionally, transfer matrix simulation is also used to calculate the electric field intensity profile through the depth of the film, wherein an enhanced electric field intensity is predicted at the surface of the implanted films. [ABSTRACT FROM AUTHOR]

Green synthesis for synthesizing silver nanoparticles (AgNPs) has been suggested as an environmentally friendly alternative to conventional physical/chemical methods. In this study, we report the green synthesis of AgNPs using a hot-melt extrusion-processed Angelica gigas Nakai (AGN) (HME-AGN) extract as a reducing agent to increase the water solubility of the active ingredient compared to the existing AGN. The mixture of the AGN extract and AgNO3 at about 420 nm could not confirm the formation of AgNPs. The synthesis of AgNPs was found to be most advantageous at 60 °C when the mixing ratio of the HME-AGN extract was 9:1 (AgNO3–extract, v/v) using 3 mM AgNO3. The physicochemical properties of the optimized AgNPs were characterized by UV–Vis spectrophotometer, dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffractometer (XRD). DLS showed the particle size average of 102.3 ± 1.35 nm and polydispersity index (PDI) value of 0.314 ± 0.01. The particle surface charge was −35 ± 0.79 mV, confirming the stability of the particles. The particle shape was spherical, as shown through TEM analysis, and the presence of silver ions was confirmed through the EDS results. FT-IR data showed functional groups of biomolecules of the extract involved in the synthesis of AgNPs. The face-centered cubic (FCC) lattice of AgNPs was confirmed in the XRD pattern. The AgNPs had an effective antifungal activity against Candida albicans (C. albicans) that was better than that of the HME-AGN extract. In conclusion, this study suggests that the synthesis of AgNPs was improved by using the HME-AGN extract with increased water solubility through HME. In addition, it was suggested that the synthesized AgNPs can be used as an improved antifungal agent compared with the HME-AGN extract with antifungal activity. [ABSTRACT FROM AUTHOR]

The numerous applications of metallic nanoparticles in different fields such as materials science, medicine, biology, led to the rapid development of various synthesis methods of these nanomaterials, among which the biogenic approach in obtaining nanoparticles has been proved to be an efficient alternative compared to other methods. The present study aims to investigate the potential of goji berries extract as source of bioactive compounds able to reduce the silver ions and to stabilize the resulting nanoparticles. Reaction parameters such as pH and AgNO3 concentration were analyzed and optimized in order to obtain spherical, well dispersed and high yield silver nanoparticles. Five different pH values (6; 7; 8; 9; 10) and five ratios fruit extract: silver nitrate solution (1:1; 1:3; 1:7; 1:10; 1:15) were investigated and it was found that the silver nanoparticles obtained at pH=9 and 1:10 ratio demonstrated the highest monodispersity and were obtained in the highest yield. The obtained nanoparticles were characterized in terms of their size and shape using transmission electron microscopy (TEM) and UV-vis spectroscopy. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) represent an excellent option to solve microbial resistance problems to traditionally used antibiotics. In this work, we report optimized protocols for the production of AgNPs using extracts and supernatants of Trichoderma harzianum and Ganoderma sessile. AgNPs were characterized using UV-Vis spectroscopy and transmission electron microscopy, and the hydrodynamic diameter and Z potential were also determined. The obtained AgNPs were slightly larger using the fungal extract, and in all cases, a quasi-spherical shape was obtained. The mean sizes of AgNPs were 9.6 and 19.1 nm for T. harzianum and 5.4 and 8.9 nm for G. sessile using supernatant and extract, respectively. The AgNPs were evaluated to determine their in vitro antibacterial effect against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) was determined, and in all cases the AgNPs showed an antimicrobial effect, with a MIC varying from 1.26–5.0 µg/mL, depending on the bacterial strain and type of nanoparticle used. Cytotoxicity analyses of AgNPs were carried out using macrophages and fibroblast cell lines. It was determined that the cell viability of fibroblasts exposed for 24 h to different concentrations of AgNPs was more than 50%, even at concentrations of up to 20 µg/mL of silver. However, macrophages were more susceptible to exposure at higher concentrations of AgNPs as their viability decreased at concentrations of 10 µg/mL. The results presented here demonstrate that small AgNPs are obtained using either supernatants or extracts of both fungal strains. A remarkable result is that very low concentrations of AgNPs were necessary for bacterial inhibition. Furthermore, AgNPs were stable for more than a year, preserving their antibacterial properties. Therefore, the reported optimized protocol using fungal supernatants or extracts may be used as a fast method for synthesizing small AgNPs with high potential to use in the clinic. [ABSTRACT FROM AUTHOR]

An effective method for reducing silver ions using gelatin (Gel) and 2-hydroxypropyl-β-cyclodextrin (HPCD) hydrogels, which stabilize silver at various concentrations is described. The formation of AgNPs in solution, as well as Gel-HPCD nanogels, is confirmed by the surface plasmon resonance (SPR) band at 420–440 nm in the UV–Vis spectrum. The resulting Gel-HPCD and Gel-HPCD/AgNPs composites are characterized using various techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). SEM images showed that the porous structure and the AgNPs are homogeneously dispersed throughout the Gel-HPCD/AgNP composites network. The AgNPs in the Gel-HPCD/AgNPs composite is crystalline, with spherical particles having an average size of 7.0 ± 2.5 nm, as determined by TEM. The Gel-HPCD/AgNPs composites are strongly effective against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The assembled antibacterial Gel-HPCD/AgNPs composites are also assessed for their cytotoxic and anticancer activities using HCT-116 cancer cells. The results suggest that Gel-HPCD/AgNPs composites could be used as effective therapeutics in the future in tissue engineering applications, as their bactericidal properties and low toxicity make them ideal for clinical use. [ABSTRACT FROM AUTHOR]

In this study, 2,2,6,6-Tetramethylpiperidin-1-yl oxyl (TEMPO) oxidized cellulose nanofibrils (CNFs) decorated with silver nanoparticles (AgNPs) have been demonstrated as hybrid framework for microorganism inhibition. The AgNPs@CNFs nanocomposite have been characterized by fourier transform infrared spectrophotometer, X-ray diffractometer, differential scanning calorimeter and thermal gravimetric analyser. The morphology, size and zeta potential of the nanocomposite was evaluated using transmission electron microscopy and dynamic light scattering while the antimicrobial activity was evaluated using disc diffusion assay. The reduction of silver ions in the presence of CNF was a function of time as the intensity of the SPR band increased with increase in reaction time. The AgNPs@CNF composite had a higher thermal stability and fiber length between 50 and 400 nm, while the average size, polydispersibility index and zeta potential were found to be 97.8 ± 17.9 nm, 0.5393 ± 0.09 and − 23.78 ± 3.71 (mV) respectively. The zone of inhibition of the nanocomposite against Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Candida albicans were found to be 8.7 ± 0.6, 10.7 ± 0.6, 8 ± 1, 11 ± 1, 10.7 ± 0.6, 10.3 ± 0.6 mm. The AgNPs@CNFs nanocomposite is a good candidate for developing antimicrobial wound dressing that can inhibit the growth of microorganism. [ABSTRACT FROM AUTHOR]

In the present work, silver nanoparticles (Ag NPs) synthetized with employing the aqueous extract obtained from grape pomace by plasma-chemical extraction technique was developed. The fabrication method was fast, low cost, and eco-friendly. The effect of silver ions concentrations, volume of extract and duration of synthesis for Ag NPs formation as well as their average particle size has been studied. The results demonstrated that synthesis provides the formation of Ag NPs for investigated concentrations of Ag+ (0.25 - 6.0 mmol L-1) during 5 - 10 minutes. The prepared Ag NPs were with an average particle size about 25 - 31 nm. From the SEM and TEM images, the Ag NPs are found to be almost spherical. The catalytic effectiveness of the prepared green catalyst, Ag NPs, was also investigated in catalytic degradation of methyl orange (MO) dye. The catalytic degradation reaction under solar irradiation was completed (97 % - 98 %) within 3 - 6 min, signifying excellent catalytic properties of Ag NPs in reduction of MO. [ABSTRACT FROM AUTHOR]

L-Cysteine (L-cys) plays very crucial role in biological systems. The study reports the colorimetric detection of L-cys at nanomolar level using chitosan capped Ag decorated NiS nanocomposite (chit-Ag/NiS NCs).The chemical reduction and co-precipitation methods were adopted to prepare chit-Ag/NiS NCs. The fabricated NCs was characterized by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), FT-Raman, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The chit-Ag/NiS NCs particularly detect L-cys even in other amino acids presence. The chit-Ag/NiS NCs showed the surface charge of −26 ± 39.9 mV. The detection of L-cys was indicated by disappearance of yellowish-brown color of Chit-Ag/NiS NCs to colorless. A good linear correlation was found between absorbance vs logarithmic concentration of L-cys (1 μM to 1 nM) with R2 value of 0.99. The chit-Ag/NiS NCs impregnated cotton swabs was prepared for real time detection of L-cys and the prepared probe was found to be highly selective and specific. The effect of pH, temperature and salinity influencing the L-cys detection was studied. Also, the antimicrobial activity of Chit-Ag/NiS NCs was investigated against gram negative (E. coli) and gram positive (B. subtilis) bacteria. [ABSTRACT FROM AUTHOR]

Poly(styrene@N‐isopropylmethacrylamide‐methacrylic acid) [P (St‐NM)] microgels were prepared via seed facilitated emulsion polymerization process. In situ reduction of silver ions was carried out to generate Ag nanoparticles in the voids of shell region of polymer microgels. Synthesized P (St‐NM) and Ag‐P (St‐NM) particles were characterized by UV–Vis spectroscopy, transmission electron microscopy (TEM), Fourier‐transformed infrared spectroscopy (FTIR), and X‐ray diffraction (XRD). The stability of Ag nanoparticles within P (St‐NM) system over the wide range of pH and temperature is also a part of this study. Thus, prepared Ag‐P (St‐NM) was tested for its catalytic efficiency against reduction of K2Cr2O7 using formic acid (FA) as reductant. Factors affecting catalytic efficiency of Ag‐P (St‐NM) system towards transformation of Cr+6 to Cr+3 were investigated. Other toxic chemicals can also be reduced using same catalytic system. [ABSTRACT FROM AUTHOR]

The green synthetic method has remarkably been used to synthesize many types of nanostructures, such as nanoparticles and nanocomposites, due to simple, inexpensive, and eco-friendly ways. In the present study, silver nanoparticles and Ag/AgFeO2 core–shell nanocomposites were synthesized, using Teucrium polium extract as a reducing and stabilizing agent. Synthesized nanoparticles and nanocomposites were characterized using several physical techniques, including dynamic light scattering method, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and ultraviolet–visible absorption spectroscopy. The mean size of the synthesized nanocomposites was 90.80 nm with a nearly spherical shape, successfully silver coating by AgFeO2 shell. Density functional theory simulations were used to evaluate nanoparticles' and nanocomposites' absorption band mechanisms. The antimicrobial properties of both Ag NPs and Ag/AgFeO2 against different types of fungi and bacteria were studied. The Ag/AgFeO2 NCs revealed superior antifungal and antibacterial efficacy even in lower concentrations compared to Ag NPs that could be applied for biomedical applications in the future. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The search for new more effective nanoparticles based antimicrobial agents has been under way in recent decades. Silver nanoparticles are hydrophobic and have a negative charge. We report on the preparation of Ag–Cu bimetallic nanoparticles with various silver contents synthesized by electric explosion of two twisted wires of the metals in argon atmosphere. The method allows to obtain nanoparticles of a given composition, has high performance and scalability. Nanoparticles were investigated using X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive analysis and microelectrophoresis techniques. We evaluated the antibacterial activity of the nanoparticles against Gram-negative E. coli and Gram-positive methicillin resistance S. aureus MRSA. Our study showed that the synthesized nanoparticles have a positive zeta potential of about 30 mV at pH 7.2 and high antimicrobial activity against the tested bacteria strains, which is close to the activity of silver nanoparticles with a size of 20 nm. The high antimicrobial activity of the nanoparticles is due to the prolonged slow release of silver and copper ions, which makes nanoalloys more effective than Cu and Ag metallic nanoparticles. The synthesized nanoparticles have high antimicrobial activity and demonstrate the potential for their use as promising new generation antibacterial agents effective against resistant microorganisms. [ABSTRACT FROM AUTHOR]

Silver-containing nanocomposites based on N-vinylpyrrolidone–sodium N-crotyl-4-aminosalicylate–crotyl alcohol triple copolymer with the silver concentration varied in a wide range were synthesized. The influence of the silver content on the spectroscopic, structural, and morphological characteristics of silver-containing nanodispersions was demonstrated by UV/visible spectroscopy and by atomic force and transmission electron microscopy. The nanodispersions studied exhibit antibacterial activity toward S. aureus Gram-positive and E. coli Gram-negative bacteria, suppressing their growth at a silver concentration of 0.01 wt %. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Microbiology is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A water-soluble chitosan derivative, chitosan succinamide, was used as a polymer matrix for the formation of silver nanoparticles via ion reduction under microwave irradiation in the presence of a D-glucose reducing agent. UV spectroscopy confirmed the presence of silver nanoparticles in the synthesized colloidal solution. Transmission electron microscopy showed that the synthesized silver nanoparticles had a spherical shape. The obtained diffractograms confirm the presence of reflexes characteristic of the crystal lattice of metallic silver. In vitro studies showed that the synthesized colloidal solution of silver nanoparticles exhibits pronounced antibacterial activity against strains of the gram-positive bacteria Bacillus subtilis ATCC 6633 and Bacillus coagulans 429. [ABSTRACT FROM AUTHOR]

Using mulberry silkworm pupae as an alternative source of renewable raw materials, a water-soluble Bombyx mori chitosan derivative N-carboxymethylchitosan is synthesized. A method for the photochemical reduction of silver ions into silver nanoparticles in an N-carboxymethylchitosan matrix is developed. The presence of silver nanoparticles in a colloidal solution is confirmed by UV spectroscopy, and their shape and size are determined by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Modified cellulose acetate antibacterial material was obtained by immobilizing Al/Ag nanoparticles on fabric fibres in water and subsequent hydrolysis of this nanoparticles under mild reaction condition. AlOOH/Ag self-assembled flower-shaped nanostructures consist of AlOOH nanoplates and Ag inclusions. The AlOOH nanosheets size is of 150–300 nm, thickness is 5–7 nm. The silver inclusions were from 5 to 30 nm in size. Flower-shaped AlOOH/Ag nanostructures change the charge of fibres and stabilize Ag nanoparticles against agglomeration. The positive charge of the modified fibres improves the bacteria adsorption due to electrostatic interaction. The antibacterial activity of the nanoparticles and modified material arise due to the slow Ag+ migration into the medium from stabilized Ag nanoparticles. The nanoparticles and modified cellulose acetate sheets were characterized by transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, FTIR spectroscopy. The release of silver ions to the medium remains low for 70 h with AlOOH/Ag@CA reducing all the tested bacterial strains below the limit of detection (102 CFU/mL) within 3 h for Escherichia coli and 6 h for MRSA due to local effects of silver on adsorbed bacteria. The antibacterial activity of modified cellulose acetate fabric allows this method of modification to be exploited to produce materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Herein, we described the modification of chitosan with cyanuric chloride as a mediator for preparation of chitosan-s-triazinyl-bis(2-aminomethylpyridine) and chitosan-s-triazinyl-bis(8-oxyquinoline) derivatives to be used as reagents for preparation of silver nanoparticles under ecofriendly conditions. These two reagents are convenient and effective for reduction of silver ions to silver nanoparticles with particle size less than 10 nm that might be suitable for industrial and medicinal applications. The formation and particle size of AgNPs are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray analysis (EDX). The antimicrobial activity of the two modified chitosan-s-triazine-AgNPs was evaluated against activities against Gram-positive bacteria (M. luteus ATCC 10240 and MRSA ATCC 43300), Gram-negative bacteria (E. coli ATCC 25922 and P. aeruginosa ATCC 75853), and C. albicans. The results showed that chitosan-s-triazinyl-bis(2-aminomethylpyridine) AgNPs showed high antimicrobial activities against all the tested microorganisms, while their analogous chitosan-s-triazinyl-bis(8-oxyquinoline) AgNPs showed moderate activities. [ABSTRACT FROM AUTHOR]

The effect of silver (Ag) and strontium (Sr) ions implanted into polycrystalline (SiC) was investigated. One batch of polycrystalline SiC wafers was implanted with 360 keV silver ions (Ag-SiC) and another implanted with 360 keV strontium ions (Sr-SiC). Both implantations were performed at 600 °C to a fluence of 2 × 1016 cm−2. Some of the Ag- SiC samples were then implanted with Sr ions of 280 keV to a fluence of 2 × 1016 cm−2 at 600 °C (Ag&Sr-SiC). The as-implanted samples were annealed at temperatures from 1000 to 1400 °C in steps of 100 °C for 5 h. The samples were thereafter characterised by Transmission electron microscopy (TEM), Raman spectroscopy, Elastic Recoil Detection Analysis (ERDA), Rutherford backscattering spectrometry (RBS), and Scanning electron microscopy (SEM). Both individual and dual implantations resulted in no amorphization of the SiC. As expected, dual implantation resulted in a higher defect concentration. Subsequent Sr implantation resulted in the formation of Ag precipitates, especially around grain boundaries. Annealing the Ag-SiC and Ag&Sr-SiC samples caused the shift of implants towards the surface accompanied by loss at 1400 °C while no loss was observed in the Sr-SiC samples. [ABSTRACT FROM AUTHOR]

Synergistic effects occurring between biologically active substances are of great importance for efficient treatment of many diseases. Therefore, the aim of research was to determine impact of sodium hexametaphosphate (HEX), which is a well-known permeabilizer, on the cytotoxicity of silver ions and two types of AgNPs towards HL-60 and U-937 tumor cells. The AgNPs were synthesized in a chemical reduction method using sodium borohydride and trisodium citrate (CITAgNPS) or sodium hypophosphite and HEX (HEXAgNPs). Imaging with the use of transmission electron microscopy (TEM) and atomic force microscopy (AFM) revealed that the AgNPs exhibited spherical shape and comparable size distribution. Electrophoretic mobility studies showed that the AgNPs were negatively charged. The mitochondrial and antioxidant activity as well as membrane lipid peroxidation and integrity after dose-dependent AgNP treatment were evaluated using biochemical assays. The impact of HEXAgNPs on the membrane integrity and inactivation of antioxidant enzymes of the cells was much higher than this one observed for CITAgNPs and silver ions of the same concentration. The membrane damage occurred as a result of lipid peroxidation which was induced by pure HEX and HEXAgNPs. It was also observed that HEX significantly increased cell membrane damage induced by CITAgNPs and silver ions although the cells exhibited different sensitivity to these components. Moreover, it was found that HEX can induce oxidative stress. Hence, it was revealed that HEX enhances AgNP activity when it is applied both as their stabilizer or supplement in their suspensions. [ABSTRACT FROM AUTHOR]

Objective(s): A combination of biological and microemulsion methods was used to synthesize silver nanoparticles for the first time. The applied method could be referred to as the biomicroemulsion method, which has the advantages of both biological and the microemulsion methods. Materials and Methods: In the present study, silver nanoparticles were synthesized in a water-in-oil biomicroemulsion using silver nitrate, which was solubilized in the water core of one microemulsion as the source of silver ions. In addition, a bacterial culture supernatant solubilized in the water core of another microemulsion was employed as the biological reducing agent, dodecane was used as the oil phase, and sodium bis(2-ethylhexyl) sulfosuccinate was applied as the surfactant. Moreover, the antibacterial activity of the nanoparticles was investigated against gram-positive and gram-negative bacteria by disc-diffusion method. Results: The UV-Vis absorption spectra, dynamic light scattering, and transmission electron microscopy were employed to characterize the presence, size distribution, and morphology of the nanoparticles, respectively. According to the results, the nanoparticles had the optimal conditions in terms of the size and distribution at the silver nitrate concentration of 0.001 M. In addition, the analysis of antibacterial activity indicated that the inhibition zone diameter of Staphylococcus aureus was higher compared to Escherichia coli. Conclusion: Silver nanoparticles were synthesized successfully using biomicroemulsion method and showed significant anti-bacterial activities against S. aureus and E. coli. [ABSTRACT FROM AUTHOR]

In this study, biosynthesis of silver nanoparticles (AgNPs) by using Eurotium cristatum, isolated from Fuzhuan brick-tea and its antibacterial activity has been demonstrated. AgNPs were characterized at 425 nm as maximum absorbance peak by ultraviolet-visible spectrophotometry. The images of transmission electron microscopy revealed that AgNPs are spherical shape with at 15–20 nm in size. The X-ray diffraction pattern corresponding to planes (111), (200), (220), (311), and (222) demonstrated the crystalline nature of AgNPs. Fourier transform infrared spectrum showed that functional groups involved in reduction of silver ions to metal nanoparticles. For antibacterial application, AgNPs showed antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, and Bacillus subtilis. It also acted synergistically with various antibiotics to inhibit growth of pathogenic strains, which produced an effect greater than the sum of their individual effects. For neomycin with no resistance to C. albicans, it combined with AgNPs, which had significant synergistic effect against C. albicans, with maximum inhibitory zone at 20.9 mm, which was 2.5-fold greater than that of AgNPs alone (8.2 mm). Other antibiotics combined with AgNPs also existed similar synergistic effect. Therefore, AgNPs-synthesized by E. cristatum could enhance antibacterial activity in combination with antibiotics against pathogenic strains through synergistic effects. It might provide a new strategy for treatment of resistant bacteria. [ABSTRACT FROM AUTHOR]

The present study was conducted to determine manganese (Mn2+) and chromium (Cr2+) ions in aqueous systems with a simple, rapid, sensitive, selective and cost-effective colorimetric approach. Sodium dodecyl sulfonate (SDS) and β-cyclodextrin (CD) were used as both stabilizer and surface functionalizing agents for the synthesis of silver nanoparticles (AgNPs). Synthesized AgNPs were characterized by FT-IR spectroscopy, UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and dynamic light scattering (DLS) techniques. The effect of pH on the stability of nanoparticles was investigated. SDS modified silver nanoparticles (SDS-AgNPs) and SDS with β-cyclodextrin modified silver nanoparticles (SDS-CD-AgNPs) demonstrated sensitive and selective colorimetric detection of Mn2+ and Cr2+ ions at ppm level, respectively. The prepared SDS-AgNPs and SDS-CDAgNPs solution showed a color change visible to the naked eye from yellow to orange upon adding Mn2+ and Cr2+ ions, respectively; however, other metal ions did not induce such a change. In addition, the results of SEM TEM and DLS" for both sensors showed the aggregation of nanoparticles after adding Mn2+ or Cr2+. Overall, the results of this study show the successful synthesis of AgNPs, SDS-AgNPs, and SDS-CD-AgNPs as simple, rapid, sensitive, selective colorimetric sensors with high potential for rapid and on-site detection of Mn2+. [ABSTRACT FROM AUTHOR]

Enterococcus faecalis (E. faecalis) is a Gram-positive bacterium closely related to many refractory infections of human and shows the resistant ability against the antibacterial effects of silver. Simvastatin is a semisynthetic compound derived from lovastatin and a hydroxymethyl glutaryl coenzyme A(HMG-COA) reductase inhibitor showing certain inhibitive effects on bacteria. The main purpose of this study was to establish and characterize the Ag+/silver nanoparticles (AgNPs)-resistant E. faecalis, and further evaluate the function of extracellular polymeric substances (EPS) in the silver resistance and the effect of simvastatin on the silver-resistance of E. faecalis. The results showed that the established silver-resistant E. faecalis had strong resistance against both Ag+ and AgNPs and simvastatin could decrease the silver-resistance of both original and Ag+/AgNPs-resistant E. faecalis. The Transmission electron microscopy (TEM), High-angle annular dark-field (HAADF) and mapping images showed that the silver ions or particles aggregated and confined in the EPS on surface areas of the cell membrane when the silver-resistant E. faecalis were incubated with Ag+ or AgNPs. When the simvastatin was added, the silver element was not confined in the EPS and entered the bacteria. These findings may indicate that the silver resistance of E. faecalis was derived from the entrapping function of EPS, but simvastatin could compromise the function of EPS to decrease the silver resistant ability of E. faecalis. [ABSTRACT FROM AUTHOR]

A simple and effective ratiometric electrochemical sensor has been developed for the detection of lead ions. This sensor was based on porous silicon nanoparticles with in situ deposition of a bismuth film. Porous silicon was prepared via electrochemical etching of silicon wafers in solution containing hydrofluoric acid, ethanol and hydrogen peroxide. The porous silicon samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. A modified electrode was applied to detect Pb(II) in water samples by differential pulse anodic stripping voltammetry. By using Bi(III) as an internal reference standard, the current ratio of Pb(II) to Bi(III) offers higher stability and reproducibility than the current of Pb(II) itself. The calibration curve in the ratiometric current signal exhibited a linear response from 0.2 to 100 μg L−1, with a limit of detection of 0.09 μg L−1 to Pb(II), enhancing the sensitivity by a factor of 1.9 in comparison with non-ratiometric methods. [ABSTRACT FROM AUTHOR]

Surface functionalization has been shown to allow tailoring of graphene lattice thus making it suitable for different applications like sensing, supercapacitance devices, drug delivery system and memory devices. In this work, surface functionalization of epitaxial graphene on SiC (EG/SiC) was done by ion beam technology (30 keV Ag− ions at fluences ranging from 5 × 1012 ions/cm2 to 5 × 1014 ions/cm2), which is one of the most precise techniques for introducing modifications in materials. Atomic force microscopy showed presence of nanostructures in ion implanted samples and Photoluminescence and X-ray photoelectron spectroscopy revealed that these are probably silicon oxy carbide. High-resolution transmission electron microscopy (HRTEM) showed decoupling of buffer layer from SiC substrate at many places in ion implanted samples. Further, HRTEM and Raman spectroscopy showed amorphization of both graphene and SiC at highest fluence. Fluence dependent increase in absorbance and resistance was observed. Gas sensors fabricated on pristine and ion implanted samples were able to respond to low concentration (50 ppb) of NO 2 and NH 3 gases. Detecting NH 3 gas at low concentration further provides a simple platform for fabricating highly sensitive urea biosensor. We observed response inversion with increasing fluence along with presence of an optimal fluence, which maximized gas sensitivity of EG/SiC. Image 1 [ABSTRACT FROM AUTHOR]

Objective: To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti. Methods: The silver nanocomposites were synthesized from Achyranthes aspera leaf extracts. The process was optimized and traced through UV-visible and photon correlation spectroscopy. The larvicidal potential of silver nanocomposites of Achyranthes aspera leaf extracts was assessed against the early fourth instars of Aedes aegypti and three non-target organisms. Furthermore, the most effective and eco-safe nanocomposite was characterized by different biophysical techniques including scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR). Results: The formulated silver nanocomposites exhibited efficient larvicidal efficacy against Aedes aegypti. Bioassay with silver nanocomposites formulated using different AgNO 3 concentrations (3, 4, and 5 mM) revealed respective LC50 values of 37.570, 6.262 and 1.041 μg/mL; 5.819, 1.412 and 0.489 μg/mL; and 5.519, 1.302 and 0.267 μg/mL after 24, 48 and 72 h. The silver nanocomposites with 4 mM AgNO3 were selected for characterization. SEM and TEM analysis revealed spherical, poly-dispersed structure with varied diameters of 1-25 nm. The XRD analysis established the crystalline and face-centred-cubic structure of silver nanocomposites with the maximum peak at a 2θ value of 37.42°. The EDX pattern showed the presence of Ag, O and C in the nanocomposites in their order of weight%. The FT-IR displayed visibly distinct peaks in different ranges demonstrating the intricacy of silver nanocomposites. In addition, the lethal concentrations of silver nanocomposites of Achyranthes aspera leaf extracts against Aedes aegypti larvae were non-toxic to non-target organisms including Gambusia affinis, Daphnia magna and Moina macrocopa. Conclusions: Silver nanocomposites synthesized with leaf extract of Achyranthes aspera provide a cost-effective and eco-safe alternative to conventional insecticides, and can be utilized as a potent mosquito nano-larvicide. [ABSTRACT FROM AUTHOR]

Novel isonicotinic acid hydrazide functionalized silver nanoparticles (INH-AgNPs) were synthesized by wet chemical method and used for the detection of Hg2+ ions in aqueous medium. The INH-AgNPs exhibit good absorbance and emission peaks by sensing Hg2+ ions with visible color changes. The detection of Hg2+ ions was confirmed by FT-IR, EDAX spectra and by the changing morphology of INH-AgNPs, and after addition of Hg2+ was confirmed by SEM and TEM imaging studies. Based on the emission intensity the probe INH-AgNPs exhibit a lowest detection limit (LOD) of Hg2+ to 0.18 nM. The association constant (Ka) of INH-AgNPs + Hg2+ ions is calculated using the Bensei-Hildebrand equation. Also, the probe is successfully utilized for the detection of Hg2+ ions in real water samples obtained from different fields, which showed good results. [ABSTRACT FROM AUTHOR]

A simple and eco-friendly method for silver nanoparticles (AgNPs) synthesis employing the aqueous extract obtained from grape pomace by plasma-chemical extraction technique was developed. The reduction of silver ions in solution was monitored using UV - Visible absorption spectroscopy. The synthesised nanoparticles were characterised using transmission electron microscopy (TEM) and dynamic light scattering measurement (DLS). The effect of silver ions concentrations and temperature on the synthesis of silver nanoparticles and average particle size was investigated. The surface plasmon resonance of AgNPs around 430 - 460 nm was observed. The sizes of the spherical silver particles were found to be in the range of 33 - 65 nm. X-ray diffraction analysis confirmed the presence of AgNPs. The study elucidates that AgNPs synthesized in such a way exhibit potential antibacterial activity against Gram positive and Gram-negative bacterial strains tested. The nanoparticles show enhanced antioxidant properties compared to the extract. [ABSTRACT FROM AUTHOR]

Silver (Ag) ions of 360 keV were implanted into polycrystalline SiC to a fluence of 2 × 1016 cm−2 at room temperature. Some of the as-implanted samples were irradiated with xenon (Xe) ions of 167 MeV to a fluence of 3.4 × 1014 cm−2 at room temperature. After implantation, the un-irradiated and irradiated samples were isochronally annealed at temperatures ranging from 1100 to 1500 °C in steps of 100 °C for 5 h. The as-implanted, irradiated and annealed samples were characterized by Rutherford backscattering spectrometry (RBS), Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Implantation of Ag at room temperature amorphized the SiC near surface implanted region, while swift heavy ion (SHI) irradiation of the as-implanted samples caused some limited recrystallization of the amorphized layer. Migration of implanted Ag was already taking place at 1100 °C in the irradiated samples while no Ag migrate for the un-irradiated sample annealed at the same temperature. These difference in the migration behavior of Ag is due to the difference in microstructure in the two samples. Irradiated samples had fine crystals with the presence of pores in the surface after annealing at 1100 °C. The pores led to the loss of about 70% of Ag from the surface. While un-irradiated samples had relatively larger crystals with less loss of silver. Decomposition of SiC were observed after annealing at 1500 °C in both samples. The results show that more Ag was released in the irradiated SiC samples. [ABSTRACT FROM AUTHOR]

Metal ion sensors are a significant and challenging area in the analytical sciences. In this study, the use of grape juice for bio-synthesizing of silver nanoparticles (AgNPs) and using it for simple and rapid colorimetric detection of Cd2+ ions is described. The as-prepared AgNPs were characterized by standard analytical techniques including UV–visible and FTIR spectroscopic methods and transmission electron microscopy (TEM). The plasmon resonance band of the silver nanoparticles was observed at 410 nm and it was found that its intensity is related to the grape juice concentration and pH. The TEM image showed the average size of 5–10 nm for AgNPs. The detection of Cd2+ ions was based on the changes of absorbance due to complex formation of the metal ion. The colorimetric detection of Cd2+ was led to a linear dynamic range from 0 to 150 µmol/L (r2 = 0.9993) and a low detection limit of 4.95 µmol/L for cadmium in aqueous solution. These results are close to or better than the previous reports. This bio-synthesized AgNPs can be used as simple alternative design for colorimetric sensing of Cd2+ in water samples. [ABSTRACT FROM AUTHOR]

Herein, novel Ag-doped PbS (Ag:PbS) nanoparticles (NPs) were synthesized via a facile and rapid microwave route. Field emission scanning electron microscopy (FESEM)/energy-dispersive X-ray (EDX) spectroscopy were employed to confirm the homogeneous doping of Ag in PbS. The transmission electron microscopy (TEM) exposed that the PbS NPs were fully encapsulated with Ag. X-ray diffraction (XRD) analysis revealed that all the samples possessed cubic crystal structures whereas the peak positions for the Ag:PbS were slightly shifted towards lower angle compared to pure PbS, further confirm the Ag doping in NPs. Fourier-transform Raman (FT-Raman) spectra also confirmed the phase and doping of Ag in PbS NPs. The grain sizes of the synthesized NPs were found to be in the range of 15–40 nm while calculated crystallite sizes of these samples were in the range of 18–26 nm. The zeta potential for 5.0 wt% Ag:PbS NPs was found to be approximately 10 times higher than that for pure PbS NPs, signifying the high stability of the doped NPs in aqueous media. The optical band gap of Ag:PbS NPs were evaluated from diffused reflectance spectra and found to be in range of 1.95–2.51 eV; increases with Ag doping. The quenching in photoluminescence (PL) intensity was observed with the increase of Ag doping concentration attributed to the charge transfer between Ag and PbS. Moreover, Ag doping also improve the electrical and dielectric properties of PbS NPs. Finally, optoelectrical properties of synthesized materials were investigated under 633 nm laser-light illumination to determine their applicability as visible-light photodetectors. It was found that the Ag doped PbS NPs exhibited enhanced photodetector figures of merit compared to the pure PbS NPs. [ABSTRACT FROM AUTHOR]

Enhanced electron field emission (EFE) behavior was observed in ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films upon irradiation with 100 MeV Ag9+-ions in a fluence of 5×1011 ions/cm2. Transmission electron microscopy indicated that while the overall crystallinity of these films remained essentially unaffected, the local microstructure of the materials was tremendously altered due to heavy ion irradiation, which implied that the melting and recrystallization process have occurred along the trajectory of the heavy ions. Such a process induced the formation of interconnected nanocluster networks, facilitating the electron conduction and enhancing the EFE properties for the materials. The enhancement in the EFE is more prominent for MCD films than that for UNCD films, reaching a low turn-on field of E0=3.2 V/μm and large EFE current density of Je=3.04 mA/cm2 for 5×1011 ions/cm2 heavy ion irradiated samples. [ABSTRACT FROM AUTHOR]