Formation Of Silver Particles Research Articles

Homogeneous silver nanoparticle loaded polydopamine/polyethyleneimine-coated bacterial cellulose nanofibers for wound dressing

Utilizing mussel-inspired chemistry is an advanced strategy for surface modification, because dopamine (DA) can form a material-independent adhesive coating and further functionalization can be achieved, including the production of silver nanoparticles (AgNPs). Nevertheless, DA easily aggregates in the nanofiber network structure of bacterial cellulose (BC), which not only blocks the pores in the BC structure but also leads to the formation of large silver particles and the burst release of highly cytotoxic silver ions. Herein, a homogeneous AgNP-loaded polydopamine (PDA)/polyethyleneimine (PEI) coated BC was constructed via a Michael reaction between PDA and PEI. Under the action of PEI, the PDA/PEI coating was uniformly attached to the BC fiber surface with a thickness of approximately 4 nm, and homogeneous AgNPs were produced on the uniform PDA/PEI/BC (PPBC) fiber surface. The sustained release of silver ions was better from AgNPs@PPBC than from AgNPs@PDA/BC. The obtained AgNPs@PPBC exhibited excellent antibacterial activities and cytocompatibility. The results of the in vivo assay indicated that the AgNPs@PPBC dressing could inhibit S. aureus infection and inflammation, promote hair follicle growth, enhance collagen deposition, and accelerate wound healing within 12 days compared with BC. These results illustrate that the homogeneous AgNPs@PPBC dressing has great potential for treating infected wounds.

Wavelength Role in Synthesis and Study of the Structure of Silver Nanoparticles Prepared by Pulsing Laser Ablation in Liquid

Silver nanoparticles (NPs) were made using double-distilled deionized water (DDDW) and pulsing laser ablation in liquid (PLAL) with Q-switched technology (Nd:YAG) laser (energy: 80[Formula: see text]mJ, number of pulses: 500) at various wavelengths (1064[Formula: see text]nm and 532[Formula: see text]nm). The surface plasmon extinction (SPE) peaks were used to measure the PLAL process’s formation quality. The SPE spectra showed a single sharp peak at about 400[Formula: see text]nm, suggesting that pure and spherical silver was produced. The formation of silver particles was verified by UV–vis spectrophotometer absorption results. According to the AFM findings, as the wavelength of the laser beam used for preparation increased, the average grain size of the particles decreased. Finally, SEM images pointing to the produced silver nanoparticles spherical in their shape, were shown. The elemental analysis and chemical characterization with energy-dispersive X-ray spectroscopy (EDX) were performed on the produced samples. This confirmed the high purity of the obtained samples and the existence of Ag NPs.

Desilicated ZSM-5 zeolites for optimized xenon adsorption at very low pressure

Selective Xe adsorption on regenerable porous materials such as activated carbons, MOFs and zeolites has been found to be promising and economically attractive. The beneficial effect of silver doping of zeolites on Xe adsorption and Xe/Kr separation has been studied for numerous zeolites such as Ag-ZSM-5, Ag-mordenite and Ag-chabazite. Among them, we had shown that Ag-exchanged ZSM-5 is the most effective material for atmospheric Xe capture and selective separation at very low pressure (ppm level). A linear tendency was observed with a ratio of 2 mol of Ag for 1 mol of strong adsorption sites. Based on this observed tendency, we hypothesize that increasing the number of exchangeable sites by lowering the Si/Al ratio could be an approach to improve silver loading and selective xenon adsorption.The aim of this study is to evaluate the impact of desilication of ZSM-5 zeolites on decreasing their Si/Al ratio and increasing the concentration of sodium-exchanged sites and, possibly, strong silver-based adsorption sites. We have shown here that light desilication of this parent ZSM-5 makes it possible to significantly increase xenon uptake at very low pressure. The desilication creates a larger concentration of Al in the zeolite and thus enables a larger concentration of silver to be loaded. Yet we found that for severe desilication, decreased xenon uptake is observed, likely due to the facilitated formation of silver particles in which the core atoms are not accessible for xenon uptake. It appears that a concentration of 0.5 mmol g−1 of strong adsorption sites is a maximum achievable value for the Ag-ZSM-5 system. Surprisingly, we found that the parent ZSM-5 zeolite prepared by organic templating yields Ag-ZSM-5 with a similar concentration of strong adsorption sites but at higher silver loading. We could hypothesize that silanol defects present in commercial zeolites may be responsible for the stabilization of silver clusters.

Formation of silver particles in [PVA:CS:PEG]-AgNO3 based biopolymer electrolyte membranes: Structural and electric transport properties study

[Chitosan (CS)-poly(vinyl) alcohol (PVA)-polyethylene glycol (PEG-200)]+xwt% silver nitrate (AgNO3) (x = 0, 10, 20, 30, 40) based biopolymer blend electrolytes (BPBEs) were prepared using solution casting method. FTIR results show the interaction of Ag+/NO3− with the constituents of polymers CS/PVA. XRD results reveal that the amorphousness increases with increasing AgNO3 concentration. Optical morphological (OM) images show that the silver, Ag(o) particles are agglomerated on the surface of the membrane. Temperature dependent dc conductivity (σdc) and dielectric relaxation frequency (fr) for BPBEs follow the Arrhenius type behavior and the sample containing 30 wt% salt has optimum dc conductivity, σdc∼1.7×10−4 S/cm at 30oC with lowest activation energy∼ 0.16 eV. The ac conductivity spectra follow the Jonscher's power law (JPL) with power law exponent, s > 1. The scaling of AC conductivity and loss tangent (tanδ) spectra were performed with respect to temperatures/concentrations of salt. The dielectric permittivity study reveals that the electrode polarization effect predominates at low frequencies. The Ionic Transference Number (ITN) measurement was used to determine the nature species of charge carrier, either ionic or electronic. The linear sweep voltammetry (LSV), result shows that 30% AgNO3containing sample has the electrochemical stability window (ESW) ∼+1.5 to -1.5 V.

BIOSINTESIS DAN KARAKTERISASI PARTIKEL PERAK EKSTRAK TANAMAN DAUN PORANG (Amorphophallus muelleri Blume) SEBAGAI PENDETEKSI ION LOGAM MERKURI

This study aims to synthesize and characterize silver particles using Porang leaf extract (Amorphophallus muelleri Blume) and determine the selectivity of silver particles as mercury metal ion detectors. The study employed Porang leaf extract as a bioreductor and stabilizer, 0.01M AgNO3 solution as a precursor, and HgCl2 salt solution and PbCl2 salt solution as standard salt solutions to be tested for selectivity. The 2 g of Porang leaves used were cleaned, cut into pieces, allowed to stand at room temperature for three days, and mashed. Porang leaf powder was added with 50 mL of demineralized water and then heated for 15 minutes at a solution temperature of 80°C. The reaction of silver particle formation was carried out by adding Porang leaf extract and AgNO3 0.01M in variations of 1:3, 1:4, 1:5, 1:6, and 1:7, then irradiating under indirect sunlight for 15 minutes. The reaction results of a mixture of colloidal extract and AgNO3 solution showed a change in color to brownish-yellow. The color change indicated the formation of silver particles. The silver particles were then characterized with a UV-Vis spectrophotometer after 15 minutes of heating, 1 hour, and 5 hours at room temperature. The results obtained with colloidal silver particles can be synthesized with a bioreductor of Porang leaf extract (Amorphophallus muelleri Blume) with optimum variations of 1:3 and 1:4. The PSa results obtained in the mixture of silver particles formed were micro-nano-sized silver particles. The results of silver particles tested against metal ions showed that silver particles selectively detect Hg (II) metal ions in HgCl2 solutions compared to Pb (II) metal ions in PbCl2 solutions.

Green synthesis, characterization, and antibacterial activity of Citrus lanatus based silver nanoparticles.

Due to their enhanced and unique physicochemical characteristics, such as their minimal dimensions, large surface area compared to their mass and increased reactivity, nanomaterials hold promise in the field of antibacterial therapy. The aim of this study is to evaluate the method for Green Synthesis, Characterization of Citrus lanatus pulp, rind, and seed-based Silver Nanoparticles, and study its antibacterial activity against common oral microorganisms. Green synthesis of nanoparticles was formulated using the extract from the rind, seed, and pulp of Citrullus lanatus and silver nitrate extract. The extract was stirred in a magnetic stirrer for 24 hours, and centrifugation was done at 8000 rpm for 10 minutes. The synthesized nanoparticles were characterized and utilized for the antibacterial study. The characterization was done using UV-visible light spectroscopy, and antibacterial activity was assessed using the well diffusion method and measuring the zone of inhibition. The nanoparticles synthesized were characterized using UV-visible spectroscopy, and the spectroscopic analysis confirmed the formation of silver particles in this study. At 450 nm, a sharp peak was observed, which correlated to the SPR band of the particles. The results showed that the zone of inhibition assessed was comparable to the standard. From this study it can be concluded that silver nanoparticles (AgNPs) produced by green synthesis from Citrullus lanatus showed significant antibacterial potential against common oral microflora.

The role of citrate in heterogeneous silver metal catalyst formation: A mechanistic consideration

The formation of silver particles as initial catalyst for the electroless copper deposition is an essential part of the formation of conductive structures in flexible electronics. In this work, we have investigated the basic mechanism using the citrate anion for the fixation of silver species and later metal catalyst formation directly on a textile substrates surface. During the particle formation process and the subsequent electroless copper deposition, silver changes its oxidation state several times. While the decomposition of bulk silver citrate leads to silver metal, the distribution on the substrate surface leads to silver oxide due to the oxidation under air. Finally, the reducing conditions in the copper deposition step, i.e. alkaline formaldehyde, convert any silver-ion to silver metal. In parallel, the thermal decomposition of silver citrate also forms CO2 and hexane-2,5-dione. The latter is the result of an auto oxidation reaction similar to Kolbe electrolysis, i.e. symmetrical radical recombination of two acetonyl radicals remaining from the decarboxylated citrate scaffold.

In situ discovery on the formation of supported silver catalysts for ethylene epoxidation

Silver particles supported on alumina are the main industrial catalysts for ethylene epoxidation. Silver catalysts are usually produced by an impregnation method followed by thermal decomposition. Although the decomposition process determines the structures and properties of silver catalysts, we are short of information on this high temperature process. Herein we employed a confocal laser scanning microscope (CLSM) equipped with a heating stage to disclose the thermal decomposition process of silver precursor towards the preparation of high selective silver catalysts. It is found that the formation of silver catalysts experiences two steps: crystallization and decomposition. The crystallization occurs at the temperature below 80℃, resulting in the formation of silver complex. Further heating the sample to 140℃, leads to the formation of silver particles at alumina wafers. The atmosphere has a significant effect on the formation and performance of catalysts. When the samples are heated in the nitrogen, small silver particles with similar size are formed, which leads to a high selectivity of ethylene epoxidation. The role of thermal atmospheres on the size and property of silver catalysts is discussed in this paper.

N,N′-Diarylformamidine Dithiocarbamate Ag(I) Cluster and Coordination Polymer

An Ag(I)formamidine cluster Ag6L16 (1) and an Ag(I)formamidine coordination polymer Ag7(L2)2 2 (L1 = N,N′-bis(2,6-disopropylphenyl) formamidine dithiocarbamate and L2 = N,N′-mesityl formamidine dithiocarbamate) have been synthesized from the reactions of L1 and L2 with AgNO3 respectively. The complexes were characterized using spectroscopic and analytical methods, including single-crystal X-ray diffraction. In the structure of 1, a six vertex distorted square bi-pyramidal octahedron is formed from an Ag6 core. The N,N′-bis(2,6-disopropylphenyl) formamidine dithiocarbamate ligands stabilize this core through two main –CS2 bridging modes giving a propeller like structure. In the structure of 2, each of the two Ag(I) centers are bridged by two N,N′-mesityl formamidine dithiocarbamate ligands forming 8-member Ag2(CS2)2 metallacycles with an inversion center in the middle of the Ag—Ag argentophilic bond. The metallacycles are connected through Ag—S bonds forming ribbons in the crystallographic a-axis. The Ag(I) centers are coordinated to two N,N′-mesitylformamidine dithiocarbamates through the dithiocarbamate S atoms. The thermal decomposition of complexes 1 and 2 had similar thermograms with one major weight loss activity and the formation of elemental silver particles thereafter.

Heatless polyol synthesis of disk-shaped silver particles and the enhanced shape control using tellurium

Despite several studies on the synthesis of silver nanoparticles, the development of an efficient and cost-effective synthesis is still a significant issue in the silver powder industry. Here, we report a simple and energy-efficient synthesis of silver particles, including disk-shaped particles, using a polyol process. This process does not require heating during synthesis, even with the use of ethylene glycol as the reducing agent, resulting in the completion of the entire reaction within a few minutes. The reaction system of this process consists of ammonium hydroxide, hydrogen peroxide, and non-transition metal elements as the catalysts. The presence of ammonium hydroxide during the reaction enabled the oxidation of ethylene glycol to glycolaldehyde without heating. Several non-transition metals were investigated as catalysts to control the shape of the silver particles. Tellurium and tin were determined to be effective catalysts for the formation of silver particles with disk shapes. The sintering behavior and electrical properties of the synthesized silver particles were investigated.

Tuning the dispersity and sphericity of silver particles by wrapping mechanism using Arabic gum

Monodisperse spherical silver micro-assemblies (AgMAs) were prepared through the chemical reaction of ascorbic acid (C6H8O6) and AgNO3. The Anhydrous citric acid (ACA) was used as the surface capping agent to generate silver nano plates (AgNPs) as primary particles. The long chain of Arabic gum (AG) was used as the carrier of primary silver to further synthesize spherical silver. The influence of ACA and AG (ACG) on the formation of silver particles via chemical adsorption is investigated systematically in the paper. AgMAs can be precisely tuned from 1.8 μm to 4.8 μm by adjusting reaction rate. It is a facile way to synthesize silver particles with high sphericity by the wrapping effect of AG, which is beneficial to the preparation of high-quality conductive paste.

Synthesis and characterization of poly(urethane)/silver composites via in situ polymerization

AbstractIn this study, poly(urethane)/silver (PU/Ag) composites were synthesized in dimethylformamide (DMF) with no essential extra reducing agents. The reaction medium DMF is acting as both a diluent and reducing agent for silver particles. Composites (PU/Ag) were synthesized by in situ polymerization in the existence of different amounts of silver nitrate. The formation of PU/Ag composites was approved by ultraviolet–visible (UV–vis) spectrometer, Fourier transform infrared (FTIR) spectroscopy, and X‐ray diffraction (XRD) analyses, scanning electron microscopy–energy dispersive X‐ray (SEM–EDX) analyses, thermogravimetric analysis/differential thermal analysis (TGA‐DTA), and differential scanning calorimetry. The conductivity measurements of PU and composites were done with the four‐point probe technique using a Keithley 2400 electrometer. The conductivity values of the undoped PU, PU5, PU10, and PU20 were about 1.18 × 10−7, 2.2 × 10−6, 2.3 × 10−7, and 1.25 × 10−7 S cm−1, respectively. The presence of silver particles was approved by UV–vis spectroscopy, EDX, and XRD. The formation of silver particles was determined by UV–Vis absorption spectra of the polymer matrix. According to TGA, it was observed that composites have higher thermal stability than polyurethane.

Features of the Semiconductor Surface structure containing silver particles on the porous Silicon Film Surface Formed by Metal-Assisted Etching

The porous silicon film surface region containing silver particles is studied by scanning electron microscopy and Raman spectroscopy. The porous silicon film is formed by metal-assisted etching of a single-crystal silicon substrate. It is found that the distribution of silver particles is controlled by the porous layer morphology. The formation of silver particles by chemical deposition results in certain smoothing of the por-Si film surface relief. In this case, the silicon crystallite structure does not change significantly.

Optical properties of sol-gel coatings containing silver nanoparticles

The technology of receiving the antireflective coating increasing efficiency of use of sunlight in various service conditions is described. Suspensions of nanodimensional silicon dioxide with tetraethoxysilane as a precursor were synthesized to solve the assigned task. The received suspensions were applied by a dipping method on glass samples followed by the coating formation on a surface of the substrates at various temperatures. As a result of a cure of the received samples under natural conditions transparent film of about 500 nanometers thick having very low strength properties on the surface of glass were formed. Heat treatment led to the improvement of strength of coatings in process with increase of temperature up to 600 °C. Exceeding of this temperature resulted in cracking of coatings. In the course of heat treatment higher than 300 °C formation of a coating was accompanied by the thermolysis of silver nitrate that was introduced into silicon dioxide suspension with a formation of silver particles which size was in the nanoscale distance limits according to the results of Auger electron spectroscopy. Presence of evenly distributed silver nanoparticles provided an antireflective effect to coatings which at visual observation found expression in the form of the interference phenomenon. The obtained data confirmed prospects of use of nanosilver as a component of coatings on the basis of silicon dioxide in order to confer the antireflective properties.

Optical and antimicrobial properties of silver nanoparticles synthesized via green route using honey

AbstractAmong the various green synthesis methods for nanoparticle synthesis, the honey-mediated green synthesis of nanoparticles is a fast, safe, biocompatible, and cost-effective method. In the present work, we demonstrate the sunlight-induced honey-mediated synthesis of silver nanoparticles and report the effect of light intensity, its color, and exposure time on the formation of nanoparticles. The visual inspection followed by UV-Vis spectral studies was performed to confirm the formation of silver nanoparticles. The HRTEM measurement confirms the formation of polydispersed silver particles. We further report the excellent antimicrobial activity of the synthesized nanoparticles against various strains of bacteria, which is found to be comparable to that of the antibiotic drug of choice. Our study points to further research on the possibility of considering these green synthesized silver nanoparticles as an alternative to antibiotics.

The deficiency of chitosan:AgNO3 polymer electrolyte incorporated with titanium dioxide filler for device fabrication and membrane separation technology

In the present work the drawbacks of chitosan:AgNO3(CS:AgNt) mediated by TiO2 filler for polymer electrolyte fabrication and membrane separation technology were discussed. The phenomena of reduction of silver ions to metallic silver particles were explained based on various techniques such as UV–vis, XRD, SEM, EDX, OM and TEM. An increase in intensity and broadness of surface plasmon resonance (SPR) peak in the UV–vis absorption spectra revealed the formation of a high amount of silver nanoparticles (Ag NPs). The high dielectric constant of TiO2 filler was responsible for the reduction of more silver ions. The crystalline peaks in XRD pattern confirmed the formation of metallic silver particles. The OM images showed Ag NPs with bulk sizes. The SEM images and EDX spectra confirmed the existence of Ag NPs. The TEM images illustrated silver particles with small sizes in CS:AgNt system. To investigate the stability of silver ions, the electrical properties were performed. The increase of resistance and decrease in dielectric constant at high TiO2 concentration confirmed the deficiency of the prepared films for electrochemical device application. Distinct peaks appeared in the imaginary (Mi) component of electric modulus spectra and no peaks were seen in dielectric loss spectra.

Formation of silver particles for SERS spectroscopy by mist chemical vapor deposition method

Silver particles on the quartz glass substrate were formed using the mist chemical vapor deposition method. The deposited particles were comprised of nano to sub-micron particle that were concentrically located. The particles were polycrystalline, and the chemical state was found to be metallic silver. By measuring rhodamine6G (R6G) solution on the silver particles as an active plate for surface enhanced Raman scattering (SERS), the peaks of the SERS signal corresponding to R6G were clearly detected down to the concentration of 10−8 mol l−1. Additionally, the SERS intensities linearly decreased with the decrease in R6G concentrations.

Environmentally friendly Finishing of Cotton Fabric via Star-like Silver micro/nano Particles Synthesized with Neem/Salep

ABSTRACT In this study, a novel silver solution was prepared by a simple green synthesis method using AgNO3, neem and salep extracts at room temperature. The results of UV-Visible spectrophotometer and Scanning Electron Microscopy (SEM) showed the formation of silver particles with a star-like morphology and sharp edges in the solution. In order to achieve an antibacterial cotton fabric, it was treated with the solution containing star-shaped silver particles by an impregnation method. Also, in order to change the surface charge of cotton fabric and more silver adsorption, a cationic surface modification was performed. Surface morphology and antibacterial properties of treated cotton fabric were characterized by SEM, inductively coupled plasma-optical emission spectrometer (ICP-OES), and antibacterial test based on the AATCC100 method, respectively. SEM images showed the presence of silver particles on the surface of treated fabric samples and ICP-OES determined the amount of silver content on the fabrics. In addition, the bacterial inhibition experiments demonstrated that the treated cotton fabrics with the star-like Ag particles synthesized by neem and salep have significant antibacterial properties against gram-positive and gram-negative bacteria. The utilized method was an easy, nontoxic, and environmentally friendly procedure for the preparation of antibacterial textiles with attractive feature in the medical and hygienic products.

Double-Helical Ag-S Rod-Based Porous Coordination Polymers with Double Activation: σ-Active and π-Active Functions.

As common coinage metals, silver and silver compounds have very rich application in the organic catalytic reaction. Immobilization of silver compounds on heterogeneous media is the most common way used in industrial catalytic reactions. In this work, we designed and synthesized a new heterogeneous porous silver catalyst, with in situ-formed Ag–S rods as connecting nodes and thiosemicarbazide-functionalized linear ligands, used in both σ- and π-catalytic transformations. Strong Ag–S bonds bypassed the loss of noble silver elements and inhibited the formation of nonporous silver particles which always led to the decrease of yields in homogenous reactions. Furthermore, various derivatives of propargylamines and phenylacetylenes were applied as both σ and π-active substrates with moderate to good yields.

The use of PWHM and Mie methods in estimation of colloidal silver particle size obtained by chemical precipitation with sodium borohydride

Unique antibacterial properties of silver have been known since the time of Egyptian pharaohs. With the discovery of antibiotics at the beginning of the twentieth century, silver is mostly pushed out from conventional medicine. However, with the excessive use of antibiotics, antibiotic-resistant super bacteria have appeared. Therefore, there is an increased interest in studying the antibacterial effects of colloidal silver. In this paper, the influence of various concentrations of silver nitrate on formation of colloidal silver particles in the solution was investigated. Colloidal silver was prepared by a chemical precipitation method using sodium borohydride as a reducing agent. As influence factors, color of the solution, Tyndall effect, UV/Vis absorption, and nanoparticle size estimated by PWHM (Peak Width at Half Maximum) and Mie methods were used. By increasing the silver concentration, color of the solution ranged from light yellow to dark yellow. All solutions showed Tyndall's effect equally. By the UV/Vis analysis it was found that the solutions absorbed radiation in the wavelength range 390-402 nm, and the intensity increased with increasing silver nitrate concentrations. By the PWHM and Mie methods silver nanoparticle sizes were estimated in the range 12-20 nm.