Reduction Of Silver Nitrate Research Articles

Role of mixed surfactants system in preparation of silver nanoparticles

Abstract Different morphologies of silver nanoparticles (AgNPs) are prepared by reducing silver nitrate with hydrazine hydrate in an aqueous solution in the presence of the anionic surfactant sodium 6,6′-((oxybis(ethane-2,1-diyl))bis(oxy))bis(3-dodecanoylbenzenesulfonate) (SOBS), the cationic surfactant cetyltrimethylammonium bromide (CTAB) and mixtures of these two surfactants as template. By mixing these cationic and anionic surfactants, different aggregates (template) were formed. The properties of the nanoproducts are studied by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray analysis and Fourier transform infrared spectroscopy. The results show that the morphology of the nanosilver can be controlled by changing the ratio of cationic to anionic surfactant in the mixture, resulting in silver nanoparticles with high crystallinity and low aggregation.

Characterization Of Phyto-Synthesized Silver Nanoparticles And Their Antimicrobial Activity Against Diabetic Foot Ulcer Bacterial Isolates.

Diabetic Foot Ulcer (DFU) is one of the major complications of Diabetes. Patients with Diabetic Foot ulcers have a high susceptibility to microbial infections and are the leading cause of hospitalization and amputation of lower limbs. In the era of increased prevalence of bacterial resistance and outbreak of resistant infectious diseases, it is very essential to develop effective therapeutic strategies towards multi-drug resistant pathogens. The antimicrobial properties of silver nanoparticles have been well studied, therefore their use in biomedicine and pharmacology is a trend. Herein we present the use of Phyto-mediated synthesized AgNPs for the treatment of diabetic foot ulcers by topical administration. The nanoparticles were synthesized by reducing silver nitrate using Terminalia chebula fruit extract. The nanoparticles were analyzed and characterized using UV-Visible Spectrophotometer, FTIR, XRD, SEM with EDAX, TEM, and DLS. The synthesized silver nanoparticles were assayed for antimicrobial activity against five Diabetic Foot Ulcer bacterial isolates i.e. Escherichia coli, Klebsiella Pneumoniae, Pseudomonas aeruginosa, Streptococcus aureus, and Bacillus subtilis. The bactericidal property of synthesized nanoparticles was analyzed by the Agar well diffusion method, which revealed the remarkable antimicrobial effects against all the selective pathogenic bacterial isolates of Diabetic foot ulcers in the present study. These results constituted the basis for further studies on the use of plant-based silver nanoparticles for the treatment of Diabetic Foot ulcers from different origins.

Daptomycin-Biomineralized Silver Nanoparticles for Enhanced Photothermal Therapy with Anti-Tumor Effect.

Silver nanoparticles as photothermal agents have the problems of low stability and low photothermal conversion efficiency. Amphiphilic daptomycin can improve the stability of silver nanoparticles, thereby improving their photothermal conversion efficiency. Herein, daptomycin-biomineralized silver nanoparticles (Dap-AgNPs) were prepared by reducing silver nitrate with sodium borohydride in the presence of daptomycin as a stabilizer and biomineralizer. The Dap-AgNPs had good solution stability and peroxidase-like activity. Furthermore, the photothermal conversion efficiency of the Dap-AgNPs was as high as 36.8%. The Dap-AgNPs displayed good photothermal stability under irradiation. More importantly, the Dap-AgNPs showed good cell compatibility with HeLa cells and HT-29 cells without irradiation by 808-nanometer near-infrared light at a concentration of 0.5 mM, and the cell viability was greater than 85.0%. However, the Dap-AgNPs displayed significant anti-tumor ability with irradiation by 808-nanometer near-infrared light, which was due to the increasing temperature of the culture medium caused by the Dap-AgNPs. In conclusion, Dap-AgNPs have potential applications as photothermal agents in the treatment of tumors.

Ultrasensitive electrochemiluminescence aptasensor based on ABEI reduced silver nanoparticles for the detection of profenofos

An ultrasensitive electrochemiluminescence (ECL) aptasensor for detection of profenofos was constructed by the reducibility and chemiluminescence property of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). ABEI was used to reduce silver nitrate (AgNO3) to silver nanoparticles (AgNPs), which could be adsorbed on the lattice of graphene oxide (GO) to form ABEI-AgNPs-GO complex. This compound could achieve excellent luminescence. The aptamer (Apt) modified (5′) by sulfhydryl groups could be immobilized on AgNPs to capture profenofos. When profenofos was present, the ECL signal of the aptasensor would be weakened. To further demonstrate the successful construction of the aptasensor, cyclic voltammetry tests were performed on an electrochemical workstation and an ECL analyzer, respectively. The standard curve and specificity experiment both showed that the sensor had the advantages of low limit of detection (LOD) and good specificity. Under the optimal conditions, the aptasensor had a good linear response for profenofos in the range of 1 × 10−1–1 × 104 ng/mL. It also had a LOD of 6.7 × 10−2 ng/mL and a correlation coefficient (R2) of 0.9991. The aptasensor had been successfully applied to the detection of profenofos in vegetables. The recovery range of the proposed ECL aptasensor was 98 % ~ 107.4 %.

Synthesis of silver nanoparticles coated with bovine serum albumin for application as vaccine carriers

Nanostructured particles represent a viable option for antigen carrier design in new vaccine development. In this research stage, some of the results obtained for the synthesis of silver nanoparticles covered with bovine serum albumin (AgNP-BSA) are presented. The silver nanoparticles were obtained by chemical reduction of silver nitrate (AgNO3) as precursor and sodium citrate (C6H5Na3O7) as reducing agent. The AgNP-BSA were obtained from the wet impregnation method using bovine serum albumin suspension at five different concentrations. The nanostructures were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), dynamic light scattering (DLS), and zeta potential (ζ).

Ag nanoparticles grafted vanadium carbide MXene as a superior anode material for lithium-ion battery: High capacity and long-term cycle capability

V 2 CT x MXene shows excellent potential in lithium-ion batteries (LIBs) due to its unique two-dimensional structure and rich surface chemistry. However, the low Li + -storage capacity contributed by the innate low conductivity seriously hinders its commercial application. Herein, Ag nanoparticles are grafted on the V 2 CT x MXene by a one-step reduced silver nitrate (AgNO 3 ). The obtained Ag nanoparticles are directly reduced from AgNO 3 by the -OH terminations of V 2 CT x MXene, which promote the conductivity of V 2 CT x /Ag. Besides, the Ag nanoparticles in the layered body structure have excellent structural strength, which boost the whole durability of the LIB by inhibiting the aggregation of V 2 CT x MXene. Further, the dependence of the battery performances on the Ag contents is investigated. We find that the most favorable Ag content is 4.0 at% which can simultaneously favor the transferability of electron and ion and the electrochemical kinetics to the most considerable extent. The V 2 CT x /Ag-40 achieves a specific capacity of 631 mAh g −1 at 0.05 A g −1 after 50 cycles, and even maintains a specific capacity of 298 mAh g −1 at 5 A g −1 after long-term 2000 cycles. The adopted in situ reduction strategy and the excellent electrochemical property of V 2 CT x /Ag nanostructure may be relevant for future anode material in LIBs. We focused on the in situ reaction mechanism and the treated V 2 CT x has a greatly improved specific capacity. • V 2 CT x /Ag MXene was synthesized by one step solution in situ reaction and the reaction mechanism was analyzed. • V 2 CT x /Ag MXene exhibited superior electrochemical performance for LIBs. • The effect of different content of surface AgNPs on V 2 CT x MXene was analyzed.

Development of Wash-Durable Antimicrobial Cotton Fabrics by In Situ Green Synthesis of Silver Nanoparticles and Investigation of Their Antimicrobial Efficacy against Drug-Resistant Bacteria.

An environment friendly and wash-durable silver nanoparticle treatment of cotton fabrics was carried out by in situ reduction of silver nitrate using Azadirachta indica leaf extract. The wash durability of the silver nanoparticles treatment on the cotton fabric was improved by pretreating the fabrics by mercerization and by adopting hydrothermal conditions of 120 °C temperature and 15 psi pressure for the in situ synthesis. The silver nanoparticle treated fabrics were characterized using scanning electron microscopy, colorimetric analysis and inductively coupled plasma mass spectroscopy. The coating of silver nanoparticles was seen to be dense and uniform in the scanning electron micrographs of the treated fabrics. An evaluation of the antibacterial efficacy of the silver nanoparticle treated fabric against antibiotic-resistant Gram-positive and Gram-negative strains was carried out. The antibacterial efficacy was found to be the highest against Bacillus licheniformis, showing 93.3% inhibition, whereas it was moderate against Klebsiella pneumoniae (20%) and Escherichia coli (10%). The transmittance data of a UV spectrophotometer (290–400nm) was used for measuring the UV protection factor of the silver nanoparticle treated fabrics. All the silver nanoparticle treated fabrics showed good antimicrobial and UV protection activity. The treatment was also seen to be durable against repeated laundering. This paper contributes the first report on a novel green synthesis approach integrating mercerization of cotton fabrics and in situ synthesis of nanoparticles under hydrothermal conditions using Azadirachta indica leaf extract for improved wash durability of the multifunctional fabric.

Bio-inspired green fabrication of silver nanoparticles (AgNPs) using aqueous leaves extract of Ipomoea carnea Jacq. To tackle multiple drug resistance MTCC bacterial strains

AgNPs are employed in several applications, and we used Ipomoea carnea aqueous leaves extract to enhance the metal nanoparticle synthesis process. This study suggested that aqueous extract from I. carnea leaves can reduce silver nitrate (AgNO3) and act as a stabilizing and capping agent. The specific Plasmon resonance (SPR) was found between 390-410 ​nm in a UV–Vis spectrophotometer. Field Emission Scanning Electron Microscope (FE-SEM) and X-ray diffraction (XRD) analysis confirm the size between 11.21-46.90 ​nm with spherical face-center-cubic (FCC) crystals. Additionally, the antibacterial activity of synthesized AgNPs was also evaluated against four standard bacterial pathogens i.e. Klebsiella pneumoniae (MTCC 432), Staphylococcus aureus (MTCC 1144), Streptococcus pneumoniae (MTCC 655), and Pseudomonas aeruginosa (MTCC 2474) and Brine shrimp lethality assay (BSLA) was used to check the toxicity. Synthesized AgNPs were found significantly effective against all MTCC strains with a 1359.03 ​ng/mL LC50 value.

Synthesis, Characterization and Comparative Anticancer Potential of Phytosynthesized Mono and Bimetallic Nanoparticles Using Moringa oleifera Aqueous Leaf Extract

In this article, we bring up facile one-step phytosynthesis of silver (Ag), gold (Au) and Ag/Au bimetallic nanoparticles by reduction of silver nitrate (AgNO3) and tetrachloroauric acid (HAuCl4) solution, using aqueous leaf extract of Moringa oleifera, known for its medicinal properties. These nanoparticles were evaluated for their cytotoxicity potential against human hepatocellular carcinoma cells (HepG2), triple-negative breast cancer cell lines (MDA-MB-231) and breast cancer cell lines (MCF-7). Physical characterization of these metal nanoparticles was done using different nanoparticles analysis techniques, which include UV–Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopic analysis, dynamic light scattering (DLS), zeta potential, X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDAX). Our data suggest that these phytosynthesized nanoparticles showed a dose-dependent cytotoxic effect on all the three tested cancer cell lines. However, AuNPs are reported to have higher cytotoxic potential with IC[Formula: see text] value in the range of 9.20–21.46[Formula: see text][Formula: see text]g/mL compared to that of bimetallic NPs (Ag–Au NPs) with IC[Formula: see text] value of 37.22–49.94[Formula: see text][Formula: see text]g/mL. Whereas, silver NPs (AgNPs) didn’t show cytotoxic activity till a concentration of 60[Formula: see text][Formula: see text]g/mL in all the three cell lines tested for 24[Formula: see text]h. Hence, this study supports the effectiveness of phytosynthesized AuNPs for the development of anticancer agents.

Silver Nanoparticle-Embedded Nanogels for Infection-Resistant Surfaces

The present study aims at fabricating carboxymethyl cellulose (CMC)-functionalized silver nanogel (CMC-Ag nanogel)-immobilized cotton fabric for preventing chronic infections. Silver-embedded CMC nanogels were prepared by the reduction of silver nitrate in the presence of fructose and CMC as the reducing and stabilizing agents, respectively. Various parameters, such as CMC concentration, reduction time, and reduction temperature, having effects on the synthesis were optimized to obtain nanogels. The formation of CMC-Ag nanogels was monitored by ultraviolet–visible (UV–vis) spectroscopy, whereas the size and morphology were investigated by transmission electron microscopy and field emission scanning electron microscopy. An average particle size in the range of 5–10 nm was achieved. Subsequently, nanogel-coated cotton fabric was further investigated for antimicrobial activity against Gram-negative and Gram-positive bacterial strains using zone of inhibition, colony count, and adhesion analyses. Almost complete (>99%) colony reduction was observed at a 300 ppm silver content. The nanogel-coated fabric also showed excellent antiadhesion behavior against Staphylococcus aureus and Escherichia coli. This investigation suggested a promising approach to design antibacterial fabrics for various biomedical applications in the human healthcare sector.

Molecular study on the effect of dandelion leaf extract and silver nanoparticles in induced diabetic albino rats

The present study investigated the antidiabetic effects of dandelion leaf extract and silver nanoparticles on diabetic albino rats at molecular level, and compared with insulin. Silver nanoparticles were prepared by green chimestry method using dandelion leaf extract as capping and reducing agent, which reduced Silver nitrate (AgNO3) into silver nanoparticles. The morphology, size and crystalline structure, of silver nanoparticles are confirmed by ultraviolet, Scanning electron microscope technique, and X-ray diffraction respectively. The formation and stability of the reduced AgNPs in colloidal solution were detected and monitored by using UV-visible spectroscopy, and the absorption peak appear at 450 nm indicating the specific surface Plasmon resonance of AgNPs. The Scanning Electron Microscope showed that the AgNPs have spherical shape with aparticular size ranging from (13 to 28 )nm.The chemical characterization of synthesized AgNPs was tested using the X-ray diffraction technique, which shows that the average crystalline size was 16nm, and the synthesized silver nanoparticles have a polycrystalline structure. Application of nanoparticles in medicine is an attractive proposition. The present study included 35 female wistar albino rats weighting 200±20 grams.

Evaluating the antimicrobial activity and cytotoxicity of polydopamine capped silver and silver/polydopamine core-shell nanocomposites

Fabrication of bioactive nanomaterials with improved stability and low toxicity towards healthy mammalian cells have recently been a topic of interest. Bioactive metal nanomaterials such as silver nanoparticles (AgNPs) tend to lose their stability with time and become toxic to some extent, limiting their biological applications. AgNPs were separately encapsulated and loaded on the surface of a biocompatible polydopamine (PDA) to produce Ag-PDA and [email protected] nanocomposites to unravel the issue of agglomeration. PDA was coated through the self-polymerization of dopamine on the surface of AgNPs to produce Ag-PDA core-shells nanocomposites. For [email protected], PDA spheres were first designed through self-polymerization of dopamine followed by in situ reduction of silver nitrate (AgNO3) without any reductant. AgNPs sizes were controlled by varying the concentration of AgNO3. The TEM micrograms showed monodispersed PDA spheres with an average diameter of 238 nm for Ag-PDA and [email protected] nanocomposites. Compared to [email protected], Ag-PDA nanocomposites have shown insignificant toxicity towards human embryonic kidney (HEK-293T) and human dermal fibroblasts (HDF) cells with cell viability of over 95% at concentration of 250 µg/mL. A excellent antimicrobial activity of the nanocomposites was observed; with [email protected] possessing bactericidal effect at concentration as low as 12.5 µg/mL. Ag-PDA on the other hand were only found to be bacteriostatic against gram-positive and gram-negative bacteria was also observed.

Antibacterial Activity of Silver Nanoparticles Synthesized by Aqueous Extract of Carthamus oxycantha M.Bieb. Against Antibiotics Resistant Bacteria

Antibiotics resistant bacteria have become a global problem as a result of the unprogrammed use of antibiotics, resulting in bacterial strains resistant to many antibiotics, or to all available antibiotics. Plants are a good source of primary and secondary metabolites that have a major role in reducing silver nitrate to silver nanoparticles (AgNPs). The production of these nanoparticles were carried out by using aqueous extract of Carthamus oxycantha M.Bieb. This can be verified by color change of the reaction solution from yellow to dark brown because of the excitation of the surface plasmon resonance. AgNPs were characterized by UV-Vis spectroscopy, where they recorded the peak at 420 nm. Fourier Transformation-infrared (FTIR) was conducted to identify the effective plant group that contributes to the formation of AgNPs and it was found that proteins and phenols have the major role in the formation of those nanoparticles. Shapes and sizes of the synthesized AgNPs were characterized by Scanning Electron Microscope (SEM) with a range of 50-80nm in size and spherical in shapes. Antibacterial activity of AgNPs were tested against Multi-Drug Resistant bacteria (MDR), Extremely antibiotics Resistant (XDR), and Pan drug-resistant (PAN) bacteria, was done in concentrations ranging from 1000-63 µg/ml. The results showed that there were significant variations between the concentrations, the tested bacteria also showed significant differences in its sensitivity to AgNPs. The results recorded a proportional relation between the type of bacterial resistance to antibiotics and it's resistant to AgNPs, therefore the most resistant bacteria to AgNPs in this study Enterobacter cloacae EN2 was resistant to all antibiotics (PAN), while Escherichia coli E11 recorded was the most sensitive bacteria to AgNPs and its resistant only to 3 antibiotics. unprogrammed use of antibiotics, resulting in bacterial strains resistant to manyantibiotics, or to all available antibiotics. Plants are a good source of primary andsecondary metabolites that have a major role in reducing silver nitrate to silvernanoparticles (AgNPs). The production of these nanoparticles were carried out by usingaqueous extract of Carthamus oxycantha M.Bieb. This can be verified by color changedof the reaction solution from yellow to dark brown because of the excitation of thesurface plasmon resonance. AgNPs were characterized by UV-Vis spectroscopy, whererecorded peak at 425 nm. Fourier Transformation-infrared (FTIR) was conducted toidentify the effective plant group that contributes to the formation of AgNPS and it wasfound that proteins and phenols have the major role in the formation of thosenanoparticles. Shapes and sizes of synthesized AgNPs were characterized by ScanningElectron Microscope (SEM) with a range of 50-80nm in size and spherical in shapes.Antibacterial activity of AgNPs were tested against Multi-Drug Resistant bacteria(MDR), Extremely antibiotics Resistant (XDR), and Pandrug-resistant (PAN) bacteria,was done in concentrations ranging from 1000-63 µg/ml. The result showed that theconcentrations from 1000-125 µg/ml inhibited all tested bacterial strains except the S1strain

Raman enhancement effect of different silver nanoparticles on salbutamol

Salbutamol is a β-adrenergic receptor agonist compound which has been abused as an animal growth promoter to improve carcass lean meat percentage. At present, the detection of salbutamol by SERS mostly uses gold colloid as substrate, which is expensive and has a high detection limit. In this report, Raman enhancement signal of salbutamol was compared with concentrated gold and silver colloids. The results show that the concentrated silver colloid prepared by reducing silver nitrate with hydroxylamine hydrochloride had superior performance. Three silver colloids with different particle sizes were synthesized by the same reducing agent and used as substrates for spectra acquisition of salbutamol to explore the enhancement performance of different silver nanoparticles sizes on salbutamol. The results showed that silver nanoparticles with larger particle sizes were more conducive to the adsorption of salbutamol. Finally, under the optimal conditions (Silver colloid A as enhanced substrate, 0.2 mol/L NaOH aqueous solution as aggregating compound), a better linear relationship between the concentration of salbutamol (ranged from 0.2 to 1 mg/L) and SERS intensity. The linear equation between SERS intensity and salbutamol concentration was C = 0.0023∙I-0.079 (mg/L) with a good linearity (R2 =0.994) and lower root mean square error (RMSEc = 0.022 mg/L), where C (mg/L) was the concentration of salbutamol solution and I was the SERS intensity of salbutamol solution. Validation set correlation coefficient was 0.988 and prediction root mean square error was 0.029 mg/L. This method provides a new idea for further reducing the detection limit of salbutamol. This study is helpful to further develop a simple and low-cost SERS detection method of salbutamol based on silver colloid.

Waterproof and Moisture-Permeable Polyurethane Nanofiber Membrane with High Strength, Launderability, and Durable Antimicrobial Properties.

Nanofiber membrane has high biological protection function because of its good waterproof and moisture permeability properties. However, this membrane usually lacks active antimicrobial properties, limiting the application in reusable bioprotective textiles. Herein, waterborne polyurethane-capped Ag nanoparticles (AgNPs) were synthesized by reducing silver nitrate in water by sodium borohydride in the presence of polyurethane. AgNP-embedded thermoplastic urethane (TPU) nanofiber membrane was prepared by electrospinning a mixed solution of AgNPs and TPU. As-prepared membranes with Ag content of 50–300 mg·kg−1 have an average diameter of 0.75, 0.64, and 0.63 μm and good fiber uniformity. The doping of AgNP-embedded nanomembrane showed increased breaking force probably because of the induced crystallization effect. Test results showed that as-prepared TPU nanofiber membrane with silver content as low as 100 mg·kg−1 showed good washing resistance. The antibacterial rates of E. coli and S. aureus remained 99.99% with 50 times of soaping or chlorine washing. The corresponding waterproof and moisture permeability properties of nanofiber membrane with a thickness of 0.1 mm remained nearly unchanged, i.e., moisture permeability of around 2600 g·m−2 per 24 h and the hydrostatic pressure resistance of around 400 Pa after 50 times of soaping or chlorine washing.

Biological Synthesis of Monodisperse Uniform-Size Silver Nanoparticles (AgNPs) by Fungal Cell-Free Extracts at Elevated Temperature and pH.

Fungi’s ability to convert organic materials into bioactive products offers environmentally friendly solutions for diverse industries. In the nanotechnology field, fungi metabolites have been explored for green nanoparticle synthesis. Silver nanoparticle (AgNP) research has grown rapidly over recent years mainly due to the enhanced optical, antimicrobial and anticancer properties of AgNPs, which make them extremely useful in the biomedicine and biotechnology field. However, the biological synthesis mechanism is still not fully established. Therefore, this study aimed to evaluate the combined effect of time, temperature and pH variation in AgNP synthesis using three different fungi phyla (Ascomycota, Basidiomycota and Zygomycota) represented by six different fungi species: Cladophialophora bantiana (C. bantiana), Penicillium antarcticum (P. antarcticum), Trametes versicolor (T. versicolor), Trichoderma martiale (T. martiale), Umbelopsis isabellina (U. isabellina) and Bjerkandera adusta (B. adusta). Ultraviolet–visible (UV-Vis) spectrophotometry and transmission electron microscopy (TEM) results demonstrated the synthesis of AgNPs of different sizes (3 to 17 nm) and dispersity percentages (25 to 95%, within the same size range) using fungi extracts by changing physicochemical reaction parameters. It was observed that higher temperatures (90 °C) associated with basic pH (9 and 12) favoured the synthesis of monodisperse small AgNPs. Previous studies demonstrated enhanced antibacterial and anticancer properties correlated with smaller nanoparticle sizes. Therefore, the biologically synthesised AgNPs shown in this study have potential as sustainable substitutes for chemically made antibacterial and anticancer products. It was also shown that not all fungi species (B. adusta) secrete metabolites capable of reducing silver nitrate (AgNO3) precursors into AgNPs, demonstrating the importance of fungal screening studies.

Trace detection of ciprofloxacin antibiotic using surface-enhanced Raman scattering coupled with silver nanostars

In recent years, the abuse of antibiotics in livestock and aquaculture has become a global concern, so the detection of antibiotic residues in food is a topic of growing interest. At present the surface-enhanced Raman scattering (SERS) technique is promising as a useful tool in trace detection of chemical substances including antibiotics. In this report, we present the trace detection of ciprofloxacin – a widely used antibiotic by recording its SERS spectrum, using a SERS substrate made of silver nanostars (AgNSs) coated on an aluminum foil. In turn, AgNSs are colloidal star-shaped silver nanoparticles that have been very simply synthesized by a two-step chemical reduction of silver nitrate in an aqueous solution at room temperature with hydroxylamine followed by trisodium citrate. The synthesized AgNSs have a total size of 250–300 nm with many pointed arms of 60–80 nm length protruding from the central core. It was found that with a SERS substrate assembled from the above AgNSs coated on an aluminum foil, due to the synergistic effect between AgNSs and aluminum foil, the Raman enhancement factor of the SERS substrate was increased significantly. As a result, a SERS substrate with a Raman enhancement factor as high as 4 × 109 was created and ciprofloxacin was detected to very low concentrations, with a detection limit of 0.23 ppb.

Preparation of concentrated stabilizer-free dispersions of uniform silver nanoparticles

Stable concentrated aqueous dispersions of uniform 10 nm silver nanoparticles were prepared in absence of colloid stabilizers by reducing silver nitrate with phloroglucinol at room temperature and elevated pH. The key feature of the precipitation process entails triggering suddenly the electrons transfer between the reacting species coexisting in a homogeneous solution (‘latent reaction mixture’). The ensuing silver nucleation occurs rapidly and uniformly in the entire reaction volume leading to the formation of highly uniform dispersed nanoparticles. The phloroglucinol oxidation byproducts play an important role in preventing the aggregation of nanoparticles and facilitating the preparation of highly stable dispersions containing up to 62 wt% Ag (5.7 mol.dm−3). A mechanism rationalizing the long-term stability of silver sols at such high metal content is proposed. The rheological properties of concentrated dispersions permit the inkjet printing of electrically conductive patterns suitable for incorporation in sensors, RFID tags, solar cells, displays, and other electronic devices.

In vitro bacteriophage-mediated synthesis of silver nanoparticles for antibacterial applications and heavy metal detection

The risk of multidrug-resistant bacteria and heavy metals contaminating the environment raises a drastic public issue. In this report, we succeeded in introducing a novel synthesis technique of silver nanoparticles (AgNPs) with antibacterial, anti-biofilm activities and detection of cadmium in water. Furthermore, we managed to reduce silver nitrate (AgNO3) using the capsid structural proteins of bacteriophage, a naturally occurring bacterial virus. The formulated AgNPs were regular in shape and ranged from 10 to 30 nm in size, as indicated from the transmission electron micrographs (TEM). Moreover, the formulated AgNPs highlighted biofilm deformation capabilities against the model bacteria, Staphylococcussciuri. Furthermore, the newly synthesized AgNPs can rapidly sense the heavy metal in a concentration of 100 µM. Thus, this study reveals the outstanding ability of the bacteriophage-mediated synthesis of AgNPs and suggests its promising activity over the traditional synthesis methods.

Synthesis of Graphene/Silver/Molybdenum Disulphide Composite for Supercapacitor Application

In this study, pristine graphene/silver/molybdenum disulphide (G/Ag/MoS2) and reduced graphene oxide/silver/molybdenum disulphide (rGO/Ag/MoS2) composites materials were prepared via green solvothermal synthesis method and evaluated as supercapacitor electrodes. The morphology and structure of composites were examined by using Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and Raman spectroscopy. SEM and TEM indicate successful reduction of silver nitrate (AgNO3) to spherical Ag nanoparticles (NPs) by sodium citrate. The Ag NPs were observed to be evenly deposited on sheets of rGO and MoS2. From the XPS analysis, the spherical Ag NPs exist in zero-valent state, reflecting successful reduction. Based on cyclic voltammetry (CV) performed under 50 mV/s scan rate, G/Ag/MoS2 ternary composite exhibits the highest specific capacitance of 56.38 F/g which is 31 % and 29 % enhancement in specific capacitance of rGO/Ag/MoS2 ternary composite and Ag/MoS2 binary composite, respectively. It is believed that the presence of graphene may provide conductive pathway and a larger surface area for the distribution of Ag NPs.