Aqueous Solution Of AgNO3 Research Articles

Synthesis of silver particles on copper substrates using ethanol-based solution for surface-enhanced Raman spectroscopy

The displacement reaction of AgNO3 and copper metal is an effective and economical way to fabricate Ag-Cu surface enhanced Raman scattering (SERS) substrates. Aqueous solutions of AgNO3 are usually used for substrate preparation. In this work, a new method for Ag-Cu SERS substrate preparation is proposed, which uses an ethanol solution rather than an aqueous AgNO3 solution. Analysis of the surface morphologies of sample substrates by field emission scanning electron microscopy (FESEM) showed that the silver nanoparticles prepared by this new method were more regular than those prepared in the traditional aqueous solution. The SERS spectra of Rhodamine 6G (R6G) adsorbed on these Ag-Cu substrates were then investigated and compared. It was found that the Ag-Cu substrates prepared by this method provide significant improvements in Raman signal sensitivity and large-area uniformity. The enhancement factor of this new substrate is about 330 times higher than that prepared using an aqueous AgNO3 solution under identical experimental conditions. It was also found that 70% of the original sensitivity of the substrate remains after 15 days of exposure to air.

Algae Mediated Green Fabrication of Silver Nanoparticles and Examination of Its Antifungal Activity against Clinical Pathogens

Algae extract has the great efficiency to synthesize the silver nanoparticles as a green route. Brown seaweed mediates the synthesis of silver nanomaterials using extract of Sargassum longifolium. For the improved production of silver nanomaterials, some kinetic studies such as time incubation and pH were studied in this work. 10 mL of algal extract was added into the 1 mM AgNO3 aqueous solution. The pH and reaction time range were changed and the absorbance was taken for the characterization of the nanoparticles at various time intervals, and the high pH level shows the increased absorbance due to the increased nanoparticles synthesis. The synthesized silver nanoparticles were characterized by Scanning Electron Microscope (SEM) showing that the shape of the material is spherical, and X-Ray Diffraction value obtained from range of (1 1 1) confirmed synthesized silver nanoparticles in crystalline nature. TEM measurement shows spherical shape of nanoparticles. The Fourier Transmittance Infrared spectrum (FT-IR) confirms the presence of biocomponent in the algae extract which was responsible for the nanoparticles synthesis. The effect of the algal mediated silver nanoparticles against the pathogenic fungi Aspergillus fumigatus, Candida albicans, and Fusarium sp. S. longifolium mediated synthesized silver nanoparticles shows cheap and single step synthesis process and it has high activity against fungus. This green process gives the greater potential biomedical applications of silver nanoparticles.

Synthesis of Polypyrrole Coated Silver Nanostrip Bundles and Their Application for Detection of Hydrogen Peroxide

We reported a facile synthesis of a stable polypyrrole coated silver nanostrip bundles (Ag NSBs-PPy) by direct reduction of Ag cations in the presence of pyrrole monomers in an aqueous solution of AgNO3 and NaOH. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) observations reveal that the Ag cations were completely reduced to Ag and the Ag NSBs-PPy morphology respectively. The observations show that the modified glassy carbon electrode with the Ag NSBs-PPy exhibits a remarkable catalytic performance for hydrogen peroxide (H2O2) detection. This is due to the large surface area of Ag NSBs-PPy which increases the ability of the modified electrode to react with H2O2. The sensor has a fast amperometric response time of less than 5 s. The detection limit and limit of quantification (S/N = 3) of two linear segments (low and high concentration of H2O2) are estimated as 0.68 μmol L−1, 2.27 μmol L−1 and 13.10 μmol L−1, 43.60 μmol L−1, respectively. In addition, the sensitivity for these two linear segments is 9.701 μA μM−1 and 0.506 μA μM−1 respectively.

Silver nanoparticle deposited layered double hydroxide nanosheets as a novel and high-performing anode material for enhanced Ni–Zn secondary batteries

Simple and facile processes to produce silver nanoparticle deposited layered double hydroxide (Ag-LDH) nanosheets are reported. By a wet chemical reduction method in an aqueous AgNO3 solution, silver ions can be readily reduced to metallic silver nanoparticles and incorporated evenly on the surface of 2D LDH nanosheets. Structure and morphology analysis of the Ag-LDH composites is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Ag-LDH composites are characterized electrochemically proving their exceptional cyclability and high discharge capacity. Electrochemical impedance spectroscopy (EIS) and four-point probe conductivity measurements show that silver modification decreases the charge transfer resistance of the anode, and improves the conductivity of the active material, which boosts the electrochemical performance of Ag-LDH composites. These newly designed Ag-LDH nanosheets may offer a promising anode candidate for high-performance Ni–Zn secondary batteries and other zinc battery applications.

Synthesis of antibacterial silver-based nanodisks and dendritic structures mediated by royal jelly

The one-step preparation of silver nanoparticles and dendritic structures mediated by aqueous royal jelly solutions has been investigated for the first time. It has been found that royal jelly (RJ) is a complex organic matrix that can be simultaneously used as a reducing and stabilizing agent in the chemical synthesis of colloidal silver-based nanostructures from aqueous AgNO3 solutions, without the requirement of additional reagents or heating sources to initiate the oxidation–reduction reactions. The resulting product consisted of very fine single-crystal disks of Ag and silver 4,4′-dimethyldiazoaminobenzene (a triazenic compound). Both kinds of particles tended to coalesce and form supramolecular dendritic structures, the AgNO3/RJ weight ratio chosen in the synthesis being a key parameter to control the crystal growth and the microstructural properties of the Ag nanodisks. Data obtained from Fourier transform infrared and Raman spectroscopy analysis indicated that these nanostructures are coated by RJ biomolecules (residues of proteins and carbohydrates). In vitro biological assays showed that these nanostructures exhibit a promising enhanced antibacterial activity against both Gram-positive and Gram-negative bacteria.

One-pot synthesis of silver nanoshells with near-infrared extinction by a thiocyanate-assisted approach

We report the one-pot synthesis of silver nanoshells with near-infrared extinction assisted by thiocyanate. Our protocol is based on sequential addition of NaSCN and NaBH4 to an aqueous solution of AgNO3 followed by addition of a water-soluble thiol, affording the silver nanoshell with an extinction band around 600–700 nm.

Effect of interphase interaction on ion transport in nanosytems based on AgI and ZnO

The effect of interphase interaction on ion transport in nanodisperse composite materials is studied by the example of the ZnO-AgI system. Ion-conducting films of composition 0.7AgI-0.3ZnO are obtained by laser ablation. Fine-crystalline AgI powder prepared by the exchange reaction of aqueous solutions of AgNO3 and KI is used as the initial material. The surface morphology of prepared samples is studied by scanning electron microscopy. Their conductivity is measured by impedance spectroscopy. The elemental composition of prepared films is determined by X-ray microprobe analysis. Phase composition is established by X-ray diffractometry. The conductivity of 0.7AgI-0.3ZnO films and pressed cylindrical samples of fine-crystalline AgI powder 5 mm in diameter and 2 mm in height with ends coated with graphite contacts is measured.

In Vitro Evaluation of Biological Activities of Silver Nanoparticles Synthesized Using Dalbergia rostrata Stem Bark

Silver nanoparticles (AgNPs) synthesized are utilized in drugs because of their pharmacological and biomedical applications and also due to their ecofriendly properties. In the present study, stable AgNPs have been synthesized from the aqueous extract of Dalbergia rostrata stem bark (DRSB), which is used both as a reducing and as a stabilizing agent. The AgNPs synthesized by ultrasonication at 25°C for 10 min were found to be stable in aqueous solution at room temperature over a period of 3 months. The quantitatively stable AgNPs formed by treating the aqueous solution of AgNO3 with the aqueous extract of the plant by reduction of Ag+ ions when monitored by UV–visible spectroscopic study revealed the surface plasmon resonance (SPR) at 425 nm. According to transmission electron micrography, the NPs were spherical and in the size range of 14 ± 4 nm. When evaluated for their anti-inflammatory and antioxidant activity by in vitro methods, AgNPs showed considerably enhanced activity compared to DRSB aqueous extract.

Thermal and thermomechanical behavior of amino functionalized and metal decorated MWCNTs/PMMA nanocomposite films

The homogeneous nanocomposites (NC) films of amino modified and metal decorated multiwall carbon nanotubes (MWCNTs) with polymethylmethacrylate (PMMA) were synthesized through in‐situ free radical polymerization. Silver metal nanohybrids (Ag/MWCNTs) were prepared by two strategies, that is, reduction of metal salt in presence of sodium dodecyl sulfate and in‐situ growth from AgNO3 aqueous solution. The amino functionalization by ball milling enhanced the dispersion of MWCNT in monomer and produced a new class of radiation resistant NC. These synthesized films were characterized by FTIR, TGA, TEM, EDX, TC, DMA, and optical microscopy to ascertain their structural morphologies, thermal stability, and mechanical strength. Microscopic studies reflect the homogeneous mixing of amino functionalized and metal decorated MWCNTs in polymer matrix contributing in the enhancement of thermal stability, thermo‐mechanical strength, glass transition temperatures, and thermal conductivity of NC even at 0.25 wt% addition of modified nanofiller. The thermal stability of NC film at 0.25 wt% loading was increased around ≂50°C and the raise of thermo‐mechanical properties was observed up to 85% at 100°C in the presence of adsorbed surfactant. Thermal and thermomechanical behavior of pre and post UV/O3 irradiated NC films has been compared with neat polymer. The results revealed that amino modified nanofiller embedded network in polymer matrix can effectively disperse the radiation and has a dramatic reinforcement effect on the nature of degradation of PMMA matrix. POLYM. COMPOS., 35:1807–1817, 2014. © 2013 Society of Plastics Engineers

Caesalpinia coriaria leaf extracts mediated biosynthesis of metallic silver nanoparticles and their antibacterial activity against clinically isolated pathogens

A rapid method for synthesis of silver nanoparticles using the leaf extracts of Caesalpinia coriaria that has high level of tannin contents is reported. For leaf extracts preparation, two methods were adopted and compared with their extracellular synthesis of metallic silver nanoparticles. Stable silver nanoparticles produced by treating an aqueous solution of AgNO3 (5mM) with the leaf extracts as reducing agent of Ag+ to Ag0. The formation of the silver nanoparticles (AgNPs) in the reaction mixture was determined using the surface plasmon resonance band shown in UV–vis spectroscopy. To identify the active biomolecules responsible for the reduction of Ag+ ion and the stabilization of AgNPs synthesized the functional group available in C. coriaria leaf extracts (CCLE) was studied by Fourier transmission infrared (FT-IR) spectroscopy. The X-ray diffraction (XRD) analysis showed the crystalline structure of metallic silver ions. The energy dispersive X-ray spectroscopy (EDX) analysis of AgNPs was confirmed the presence of pure elemental silver ion with no other impurity peaks. The morphology and topography of the AgNPs were determined using field emission scanning electron microscopy (FESEM). The size of the silver nanoparticles was differed by the kind of leaf extracts used for synthesis. The morphology of the AgNPs synthesized using boiled leaf extracts was found to be triangle shape with diameter range from 40nm to 52nm whereas in the case centrifuged leaf extracts, three shapes viz., triangle, hexagonal and spherical were noticed with an average size between 78nm and 98nm. Furthermore the synthesized AgNPs were found to show potential antimicrobial activity against multidrug resistant Gram-positive (Escherichia coli and Pseudomonas aeruginosa) and Gram-negative (Klebsiella pneumoniae, and Staphylococcus aureus) clinically isolated human pathogens. The present results clearly indicated that the CCLE is a good nontoxic source for extracellular synthesis of AgNPs in eco-friendly way as compared to other methods. Thus C. coriaria leaf extracts provide a potential source for development of commercially important industrial products including cosmetics and nanomedicines by tagging nanoparticels with tannins in the future.

Photocatalytic properties of lanthanide tungstates Ln2W2O9 (Ln=La, Pr, Nd, Sm, and Gd)

Lanthanide tungstates, Ln2W2O9 (Ln=La, Pr, Nd, Sm, and Gd), were prepared via the polymerized complex method at 1273K for 2h, and their photocatalytic activities for hydrogen and oxygen evolution were investigated. Pt-loaded Gd2W2O9 exhibited activity for H2 evolution from an aqueous methanol solution under light irradiation (λ>300nm). The remaining Ln2W2O9 were inactive for H2 evolution due to the influence of the Ln elements and their crystal structures. All Ln2W2O9 were inactive for O2 evolution from an aqueous AgNO3 solution due to the lack of O2 evolution sites on the surface.

Targeted dendrimer-stabilized gold nanoparticles for computed tomography imaging of cancer cells

There has been extensive research on drug delivery from biodegradable polymeric devices. Biodegradable polymers were widely and successfully used for tissue engineering because of their biocompatibility, biodegradability,metabolizability, low toxicity and so on. In the past decade, significant effort has been directed to the development of coaxial electrospun nanofibers for treatment of disease with binary release control. Up to now just two different growth factors were physically and chemically loaded into a single nanofibrous matrix [1]. Here, we report a system in which a mixture of poly (vinyl pyrrolidone) (PVP) and nanosilver was used as the shell and PLLA with a model drug as the core. Nanosilver particles (NSPs) were rapidly synthesized from AgNO3 aqueous solutions containing PVP via microwave irradiation. The mass ratio of AgNO3 and PVP was 1:5. AgNO3 solutions were preheated for 3 min via microwave irradiation. PVP/NSP composites were prepared by electrospinning of 10 wt.% PVP solutions that contained NSPs in water (Scheme 1). Therefore, these composites could be applied as tissue engineering and antimicrobial materials [2]. PLLA (polylactic acid) and model drug were mixed and agitated overnight on a magnetic stirrer at room temperature. The solvent was a mixture of dimethyl formamide and acetone (2:1, v/v). In vitro release and antimicrobial tests showed that the binary-drug loaded fibermats not only were antimicrobial, but also released a model drug in an ideal way for 6 days.

Preparation and Formation Mechanism of the Highly Dispersive Silver Powders Used for the Front Paste of the Solar Cell

The preparation of highly dispersive silver particles of average particle size of 1~2μm used for the front paste of the solar cell were carried out by rapid addition of ascorbic acid solution into the aqueous AgNO3 solution at room temperature. The dispersive quasi-spherical silver particles were obtained with the AgNO3 concentration of 0.1M, AgNO3/Ascorbic acid mass ratio of 1:0.8 without controlling the pH value of the system. Elevating the concentrations of the AgNO3 solution resulted in the formation of flowerlike structures. The formation mechanism was investigated, it was concluded that the growth process of the highly dispersive silver particles include three stages, first, the formation of the precursor, followed by the nuclei burst and the diffusive growth process due to formation of H+ ions adsorbed on the negative charged Ag nuclei as well as the steric effect of the ascorbic acid molecule, finally, when the pH value decreased dramatically to approaching the isoelectric point, the adsorbed H+ was released and the resulting primary particles in turn aggregated to form secondary particles.

Glucose biosensors based on Ag nanoparticles modified TiO2 nanotube arrays

A GOx/Ag/TiO2 glucose biosensor was achieved by photoreducing Ag nanoparticles on TiO2 nanotube arrays (NTAs) following with adsorption of GOx. The morphology, structure, and element component of Ag/TiO2 NTAs were characterized by scanning electron microscope, transmission electron microscope, and X-ray diffraction. Ag nanoparticles were uniformly deposited on surface of TiO2 NTAs with average size of 15 nm and the size and distribution changed with the immersing time of TiO2 NTAs in AgNO3 aqueous solution. Electrochemical properties of Ag/TiO2 NTAs were characterized by cyclic voltammetry and amperometric detection of H2O2, revealing that TiO2 NTAs with immersing time of 30 min achieve the best electrochemical activity. The GOx/Ag/TiO2 NTAs biosensor with optimum conditions achieves a sensitivity of 0.39μA mM−1 cm−2 with liner range from 0.1 to 4 mM.

One-step synthesis of silver nanoparticles in an aqueous solution and their antibacterial activities

A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented in this research. In the synthesis, an amino-terminated hyperbranched polymer (HBP-NH2) was applied as a stabilizer and a reductant. The syntheses, performed at various initial AgNO3 concentrations (0.28–0.56 g/l) in a 2 g/l HBP-NH2 aqueous solution, produced silver colloid nanoparticles having average sizes from 3 to 30 nm with narrow size distributions. The formation of silver colloid nanoparticles was characterized by Fourier Transform Infrared Spectrophotometry (FTIR), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), UV/Visible Absorption Spectrophotometry, and X-ray Diffraction (XRD) measurements. The results indicated that both particle size and the UV absorption are strongly dependent on the initial AgNO3 concentrations. The silver colloid nanoparticles, prepared with a 0.35 g/l AgNO3 aqueous solution in the presences of 2 g/l HBP-NH2, showed good antibacterial activities against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). A very low concentration of nano-silver (as low as 3.0 ug/ml Ag) also gave excellent antibacterial performance.

The similarities and differences in structural characteristics and physico-chemical properties of AgAlBEA and AgSiBEA zeolites

AgAlBEA and AgSiBEA zeolites have been prepared by two preparation procedures. The conventional wet impregnation is used to obtain AgAlBEA with silver present mainly in extra-framework position. The two-step postsynthesis procedure which consists of first creating the vacant T-atom sites with associated silanol groups by treatment of TEABEA zeolite with nitric acid and then impregnating of resulting SiBEA zeolite with an aqueous solution of AgNO3 is used to obtain AgSiBEA zeolites with silver present mainly in framework position. The incorporation of Ag ions into the vacant T-atom sites of the framework of SiBEA zeolite as mononuclear Ag(I) has been evidenced by combined use of P-XRD, diffuse reflectance UV–vis, FTIR and XPS. The consumption of OH groups has been monitored by FTIR. The Brønsted and Lewis acidity of AlBEA, AgAlBEA, SiBEA and AgSiBEA has been identified by FTIR spectroscopy of adsorbed pyridine and CO as probe molecules. The catalytic activities of AgAlBEA and AgSiBEA in SCR of NO with ethanol have been investigated. These studies show that silver environment and acid–base properties play a significant role in catalytic activities of these Ag containing BEA zeolites.

Green synthesis of silver nanoparticles by microorganism using organic pollutant: its antimicrobial and catalytic application

A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO3 using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10h, and AgNPs showed characteristic surface plasmon resonance around 410nm. Spherical nanoparticles of size less than 30nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH4. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated.

Properties of novel polyvinyl alcohol/cellulose nanocrystals/silver nanoparticles blend membranes

Novel polyvinyl alcohol (PVA) blend membranes containing cellulose nanocrystals (CNs) and silver nanoparticles (AgNPs) were prepared via a simple method. CNs were prepared by sulfuric acid treatment of microcrystalline cellulose. AgNO3 aqueous solution mixed with the CNs aqueous suspension and was reduced by NaBH4 at room temperature. Purified CNs/AgNPs nanocomposites as functional fillers mixed with polyvinyl alcohol to prepare blend membrane. The morphology, mechanical properties, and antibacterial activities of PVA/CNs/AgNPs composite films were investigated. The PVA/CNs/AgNPs composite films were stable and homogeneous. The tensile strength of PVA was increased from 57.02MPa to 81.21MPa when filled with CNs/AgNPs. Antibacterial ratio of PVA/CNs/AgNPs composite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was 96.9% and 88.2%, respectively. The CNs/AgNPs nanocomposites could be applied as bi-functional nanofillers within PVA to improve the mechanical properties and antibacterial activities.

Hybrid systems of gold and silver nanoparticles generated on cellulose surfaces

Developing methods for immobilizing metallic nanoparticles (NP) onto different surfaces is a subject of fundamental interest, as nanometric structures enable the appearance of novel properties, absent in bulk or even in micrometric dimensions. In fact, the presence of NP with different size and shape on surfaces can induce substantial modifications on their electronic, optical, magnetic, physical or chemical proprieties. This will be very useful for many applications in different areas ranging from electronics to biomedicine.In this work, we use a simple, reproducible and economic method to grow metallic gold and silver NP directly on cellulose surfaces. A prior chemical activation of the alcohol groups on the cellulose surface is needed for grafting amino functions, which will complex silver and gold ions. Therefore, NP nucleation is only allowed and selectively accomplished on these seed coordination sites. The growth of NP is achieved by the interaction of aqueous dilute solutions of AgNO3 or NaAuCl4 with the cellulose surface. The procedure limits the generation of NP only to the cellulose surface, keeping the dispersion medium completely exempt of them. The resulting NP are, consequently chemically immobilized on the cellulose surface. The chemical anchoring of the NP to the surface avoids particle desorption and extends the lifetime of the resulting hybrid materials. Following this procedure, silver and gold NP could be successfully created on cellulose and this was supported by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM).The present AFM (Figure 1) study enabled to characterize the size and shape of silver NP: they are spherical and have a diameter of ~15 nm. SEM image of Ag NP (Figure 2) display the existence of NP agglomerates. Comparison of the two images suggests size and spatial distributions strongly non- uniform. It is now a challenge to deposit nanoparticles in an organized manner, achieving a regular surface functionalization of cellulose. In TEM (Figure 3) we see a sample where Ag and Au salts interacted simultaneously with the cellulose surface. Crossing the images with other information from analytical techniques, it seems that Ag NP and Au NP form mainly separately instead of presenting a core-shell structure. Also, there is evidence that larger NP are the ones made of silver which suggests that the final result is kinetically (and not thermodynamically) controlled.The authors acknowledge FCT for A.M. Ferraria Grant SFRH/BPD/26239/2006, for A. P. Carapeto Grant SFRH/BD/75734/2011 and strategic projects PEst-OE/CTM/LA0024/2011 and PEst-OE/CTM-UI0084/2011.

Photocatalytic Activity of TiO<SUB>2</SUB> Nanotubes Doped with Ag Nanoparticles

TiO2 nanotubes formed on the surface of commercially pure titanium were prepared by anodizing processing and were then heat-treated. The silver doping was processed with different molar concentration of AgNO3 aqueous solution. The silver-doped TiO2 nanotubes were characterized using field emission scanning electron microscopy, ultraviolet visible near-infrared spectrophotometer and ampere-volts (I-V) curve system. The 20-100 nm Ag nanoparticles were well doped atop, inside, and between the nanotubes. The I-V curve of the TiO2 nanotubes increased with heat treatment temperature. The silver-doped TiO2 nanotubes with anatase plus rutile phases had better photocatalytic activity.