AgNO3 Concentration Research Articles

In vitro and in vivo comparative analysis of antibacterial activity of green-synthesized silver nanoparticles.

This study aims to compare antibacterial effects of green-synthesized silver nanoparticles (AgNPs) with silver nitrate (AgNO3 ). AgNPs were successfully synthesized using Eucalyptus camaldulensis leaf extract as a reducing and stabilizing agent. Minimum inhibitory concentrations (MIC) of AgNPs and AgNO3 against Staphylococcus aureus and Pseudomonas aeruginosa ranged between 4.8-6.75μg/mL. Growth curves demonstrated that inhibition of P. aeruginosa occurred right after AgNPs were added and throughout the period of the study (72h). Antibacterial effects of both AgNPs and AgNO3 could be abrogated by cysteine and 2-mercaptoethanol, thiol-containing compounds. Galleria mellonella model revealed relatively low toxic effects of both AgNPs and AgNO3 . At 20MIC of AgNPs (≈137.8mg/kg), more than 80% survival of G. mellonella was observed. Unexpectedly, silver-containing agents could not rescue larvae after S. aureus infection. Further ex vivo experiments in the presence of coelomic larval fluid demonstrated the reduction of antibacterial activity of both AgNPs and AgNO3 . We speculated that anionic molecules present in the coelomic fluid might neutralize the action of Ag ions. Binding of AgNPs or AgNO3 to albumin, a major protein in human blood which transport several endogenous compounds was not detected, indicating that the silver-containing agents could be applied as an antimicrobial agent. This article is protected by copyright. All rights reserved.

Fast and easy synthesis of silver, copper, and bimetallic nanoparticles on cellulose paper assisted by ultrasound

This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO3 and CuSO4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method.

Morphology-Controlled Growth of Crystalline Ag-Pt-Alloyed Shells onto Au Nanotriangles and Their Plasmonic Properties.

The surface plasmon resonance of noble-metal nanoparticles depends on nanoscale size, morphology, and composition, and provides great opportunities for applications in biomedicine, optoelectronics, (photo)catalysis, photovoltaics, and sensing. Here, we present the results of synthesizing ternary metallic or trimetallic nanoparticles, Au nanotriangles (Au NTs) with crystalline Ag-Pt alloyed shells, the morphology of which can be adjusted from a yolk-shell to a core-shell structure by changing the concentration of AgNO3 or the concentration of Au NT seeds, while the shell thickness can be precisely controlled by adjusting the concentration of K2PtCl4. By monitoring the growth process with UV-vis spectra and scanning transmission electron microscopy (STEM), the shells on the Au NT-Ag-Pt yolk-shell nanoparticles were found to grow via a galvanic replacement synergistic route. The plasmonic properties of the as-synthesized nanoparticles were investigated by optical absorbance measurements.

Biosynthesis of silver nanoparticles using nitrate reductase from Aspergillus terreus N4 and their potential use as a non-alcoholic disinfectant.

Green technology has been developed for the quick production of stabilized silver nanoparticles (AgNPs), with the assistance of nitrate reductase from an isolated culture of Aspergillus terreus N4. The organism's intracellular and periplasmic fractions contained nitrate reductase, with the former demonstrating the highest activity of 0.20 IU/g of mycelium. When the fungus was cultivated in a medium comprising 1.056% glucose, 1.836% peptone, 0.3386% yeast extract, and 0.025% KNO3, the greatest nitrate reductase productivity of 0.3268 IU/g was achieved. Statistical modeling via response surface methodology was used to optimize the enzyme production. The periplasmic and intracellular enzyme fractions were found to convert Ag+ to Ag0, initiating synthesis within 20min, with predominant nanoparticle sizes between 25 and 30nm. By normalizing the effects of temperature, pH, AgNO3 concentration, and mycelium age with a variable shaking period for enzyme release, the production of AgNPs with the periplasmic fraction was optimized. The synthesis of nanoparticles occurred at temperatures of 30, 40, and 50°C, with the highest yield observed at 40 and 50°C during shorter incubation periods. Similarly, the nanoparticles were synthesized at pH levels of 7.0, 8.0, and 9.0, with the greatest production observed at pH 8.0 and 9.0 at lower incubation periods. The antimicrobial activity of AgNPs was demonstrated against common foodborne pathogens, including Staphylococcus aureus and Salmonella typhimurium, indicating their potential as non-alcoholic disinfectants.

Phytosynthesis of silver nanoparticles@graphene oxide using Mangifera indica leaves extract at room temperature: The simultaneous effects of synthesis conditions on controlled particle size and colorimetric sensing of H2O2

In this study, the silver nanoparticles@graphene oxide (AgNPs@GO) nanocomposite was successfully fabricated using Mangifera indica leaves extract as a reducing agent and stabilizer. The simultaneous effects of different synthesis parameters, including the extract concentration, the concentration of AgNO3, and the mass ratio between GO and AgNO3 (GO/AgNO3 ratio) were investigated via response surface methodology according to the Box-Behnken model, in which the particle size was calculated via scanning electron microscope (SEM) images. The results indicated the high compatibility of the model with the experimental data with the correlation coefficient R2 of 0.9948. Additionally, the optimal conditions for the fabrication of the AgNPs@GO were determined to be 1.476 mg/mL of extract, 0.111 mg/mL of AgNO3, and the GO/AgNO3 ratio of 0.307 with an estimated particle size of 22.002 nm. Besides, the calculated particle size from SEM images was also compared with the values determined using Mie theory, which indicated relative compatibility between the two calculation approaches. The H2O2 colorimetric detection of the material was also evaluated. The result also showed that while the detection of H2O2 showed a significant variation within different synthesis conditions, the limit of detection value calculated from all samples showed the lowest value of the limit of detection <60 μg/L, indicating the great potential of the material in practical applications.

Optimization and bio-fabrication of phyto-mediated silver nanoparticles (Ag-NPs) for antibacterial potential

This report examines the bio-fabrication of silver nanoparticles (Ag-NPs) utilizing AgNO3 and leaf extract of Crataegus monogyna as the precursor material. In order to maximize the antibacterial efficacy against Staphylococcus aureus, Proteus mirabilis, Klebsiella pneumoniae and Pseudomonas aeruginosa, the reaction conditions for the green fabrication of Ag-NPs were optimized. A one factor at a time approach (volume concentration of extract, volume concentration of AgNO3, pH and temperature) was used to optimize the best condition, and results were assessed through UV-visible spectroscopy and particle size distribution. The results showed that 20 mL of plant extract, 80 mL of AgNO3, pH 08, 100 °C temperature were the optimum reaction conditions under which we obtained the smallest Ag-NPs (7 nm). The scanning electron microscopy and X-ray diffraction analysis confirmed the spherical and crystalline nature of Ag-NPs. The antibacterial activity assay demonstrated a high antibacterial effect of Ag-NPs against S. aureus, P. mirabilis, K. pneumoniae and P. aeruginosa, and that impact was greater with smaller-sized nanoparticles (7 nm). This study shows that leaf extract of C. monogyna is a possible medium for the green fabrication of Ag-NPs, and control over reaction factors can establish the characteristics and antibacterial effectiveness of Ag-NPs. Communicated by Ramaswamy H. Sarma

Characterizing the Size Distribution of Silver Nanoparticles Biofabricated Using Calotropis gigantea from Geothermal Zone

This research aims to synthesize silver nanoparticles (AgNPs) using an aqueous leaf extract of Calotropis gigantea obtained from the geothermal manifestation Ie Seu-Um, Aceh Besar, Aceh Province, Indonesia. The C. gigantea leaf extract was mixed with AgNO3 solutions at concentrations of 2, 5, and 9 mM, respectively. The mixture was stirred at 80 rpm by a magnetic stirrer for 48 hours in the dark. The change in solution color indicated the reduction of Ag+ to Ag0. The resulting AgNPs synthesized using C. gigantea leaf extract (AgNPs-LCg) exhibited cloudy grey, reddish dark brown, and light brown colors when synthesized with AgNO3 concentrations of 2, 5, and 9 mM, respectively. The particle sizes of AgNPs-LCg had maximum frequencies at 246.98 nm (synthesized using AgNO3 2 mM), 93.02 nm (synthesized using AgNO3 5 mM), and 171.25 nm (synthesized using AgNO3 9 mM). The zeta potential values of AgNPs-LCg using 2, 5, and 9 mM AgNO3 were -41.9, -40.1, and -31.4 mV, respectively. Based on the solution color, nanoparticle size, and stability value of AgNPs, it can be concluded that the use of AgNO3 at 5 mM is optimal for the green synthesis process of AgNPs-LCg.

Expeditious and Eco-friendly fabrication of Graphene-Ag nanocomposite for methyl paraben sensing

The synthesis of graphene-based nanocomposites using wet chemical techniques entails a number of time-consuming and laborious synthesis stages in addition to the use of potentially dangerous substances. The present article provides a novel approach to green and in-situ synthesis that employs no hazardous chemicals and synthesizes graphene and silver nanoparticles (Ag NPs) nanocomposite from the tea tree oil and silver nitrate (AgNO3) vapours. The synthesis happens in a matter of seconds in microwave plasma at ambient conditions. Images from the scanning and transmission electron microscopy revealed that graphene nanosheets act as the most favoured sites for the Ag NPs to anchor and form a nanocomposite. The investigations revealed a correlation between the concentration of AgNO3 in the precursor and the size and aggregation of Ag NPs. The results of X-ray photoelectron spectroscopy demonstrated a negative shifting of the Ag-doublet, which suggested a strong interaction between Ag NPs and graphene. Additionally, the graphene-Ag nanocomposite drop-casted on screen-printed electrode demonstrated good electrochemical sensing capability for methyl paraben, with a superior linear range of 20 to 260 µM and a commendable limit of detection of 2.5 µM.

Remarkable enhancement of the catalytic properties of gold nanostars with silver coating

Gold nanostars (AuNSs) have attracted great attention owing to their interesting morphology, which makes them excellent for numerous applications, especially for catalysis and surface-enhanced Raman scattering (SERS). The SERS properties enhance as the size of AuNSs increases. On the contrary, there is a drastic decrease in their catalytic activity. In this work, we show that the catalytic activity of AuNSs of larger size (roughly 500 nm) can be markedly improved by coating them with silver (Ag). The AuNSs and their Ag coating were performed using the seed-mediated method. We optimized the reaction conditions during the coating process to prevent secondary nucleation within the growth solution. The Ag-shell thickness can be increased by simply using a higher concentration of AgNO3 and ascorbic acid in the growth medium. Furthermore, the Ag-coated AuNSs ([email protected]) were used for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and the catalytic degradation of anionic azo dye methyl orange (MO). The catalytic activity of AuNSs increases with an increase in Ag-shell thickness. For optimum silver shell thickness, the catalytic activity increased by 45-fold and 18-fold, compared to AuNSs, for the reduction of 4-NP and MO, respectively. This remarkable enhancement in catalytic properties implies that [email protected] have a great potential for multifunctional applications e.g., catalytic mechanistic studies using SERS.

Application of Red Onion Peel Extract for Green Synthesis of Silver Nanoparticles in Hydrogels Exhibiting Antimicrobial Properties

UV-initiated green synthesis of metal nanoparticles by using plant extracts as photoreducing agents is of particular interest since it is an environmentally friendly, easy-to-maintain, and cost-effective method. Plant molecules that act as reducing agents are assembled in a highly controlled way which makes them suitable for metal nanoparticle synthesis. Depending on the plant species, their application for green synthesis of metal nanoparticles for diverse applications may contribute to the mediation/reduction in organic waste amounts, thus enabling the implementation of the circular economy concept. In this work, UV-initiated green synthesis of Ag nanoparticles in hydrogels and hydrogel’s thin films containing gelatin (matrix), red onion peel extract of different concentrations, water, and a small amount of 1 M AgNO3 have been investigated and characterized using UV-Vis spectroscopy, SEM and EDS analysis, XRD technique, performing swelling experiments and antimicrobial tests using bacteria (Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa), yeasts (Candida parapsilosis, Candida albicans) and microscopic fungi (Aspergillus flavus, Aspergillus fumigatus). It was found that the antimicrobial effectiveness of the silver-enriched red onion peel extract–gelatin films was higher at lower AgNO3 concentrations as compared to those usually used in the commercially available antimicrobial products. The enhancement of the antimicrobial effectiveness was analyzed and discussed, assuming the synergy between photoreducing agent (red onion peel extract) and silver nitrate (AgNO3) in the initial gel solutions leading to the intensification of Ag nanoparticles production.

Synthesis of Silver Nanoparticles using Gandaria Seeds Bioreductor

The silver nanoparticles (NPP) are synthesized with the chemical reduction method by using a water extract bioreductor of gandaria seed (Bouea macrophylla G.) which acts as a reducing precursor, in this case, AgNO3 Ag+ is reduced to AgO. The concentration of AgNO3 is made between 0.5 mm and 1 mm. The characteristic of NPP is unstable, so a modification is needed with and without the addition of PVA 1 %. The process of NPP shaping is monitored by observing the uptaken of UV - Vis when the color changes occur. The high NPP concentration of AgNO3 has higher absorbance and is wider if compared to the lower AgNO3 concentration. The result of this research based on the absorbance value and the wavelength showed the NPP synthesized without the addition of PVA 1 % (b/v) is wider. The addition of PVA 1 % (b/v) provides better stability and maintains the absorbance of spectrum changes from day to day. The maximum uptaken of UV-Vis from NPP AgNO3 0.5 mm by using green synthesis and 1 mm without adding PVA are 0.946 and 0.980, respectively. However, NPP with the addition of PVA has 0.968 and 0.978 absorbance. The best concentration of NPP produced was 1 mm AgNO3.

Lignin-facilitated growth of Ag/CuNPs on surface-activated polyacryloamidoxime nanofibers for superior antibacterial activity with improved biocompatibility

IntroductionNanofibers are one of the role-playing innovations of nanotechnology. Their high surface-to-volume ratio allows them to be actively functionalized with a wide range of materials for a variety of applications. The functionalization of nanofibers with different metal nanoparticles (NPs) has been studied widely to fabricate antibacterial substrates to battle antibiotic-resistant bacteria. However, metal NPs show cytotoxicity to living cells, thereby restricting their application in biomedicine. ObjectivesTo minimize the cytotoxicity of NPs, biomacromolecule lignin was employed as both a reducing and capping agent to green synthesize silver (Ag) and copper (Cu) NPs on the surface of highly activated polyacryloamidoxime nanofibers. The activation of polyacrylonitrile (PAN) nanofibers via amidoximation was employed for enhanced loading of NPs to achieve superior antibacterial activity. MethodologyAt first, electrospun PAN nanofibers (PANNM) were activated to produce polyacryloamidoxime nanofibers (AO-PANNM) by immersing PANNM in a solution of Hydroxylamine hydrochloride (HH) and Na2CO3 under controlled conditions. Later, Ag and Cu ions were loaded by immersing AO-PANNM in different molar concentrations of AgNO3 and CuSO4 solutions in a stepwise manner. The reduction of Ag and Cu ions into NPs to fabricate bimetal-coated PANNM (BM-PANNM) was carried out via alkali lignin at 37 °C for 3 h in a shaking incubator with ultrasonication every 1 h. ResultsAO-APNNM and BM-PANNM hold their nano-morphology except for some changes in fiber orientation. XRD analysis demonstrated the formation of Ag and CuNPs as evident from their respective spectral band. Maximum 8.46 ± 0.14 wt% and 0.98 ± 0.04 wt% Ag and Cu species were loaded on AO-PANNM, respectively as revealed by ICP spectrometric analysis. The hydrophobic PANNM turned into super hydrophilic, having WCA of 14 ± 3.32° after amidoximation which further reduced to 0° for BM-PANNM. However, the swelling ratio of PANNM reduced from 13.19 ± 0.18 g/g to 3.72 ± 0.20 g/g for AO-PANNM. Even at the third cycle test against S. aureus strains, 0.1Ag/Cu-PANNM, 0.3Ag/Cu-PANNM, and 0.5Ag/Cu-PANNM displayed bacterial reduction of 71.3 ± 1.64 %, 75.2 ± 1.91 %, and 77.24 ± 1.25 %, respectively. On 3rd cycle test against E. coli, above 82 % bacterial reduction was noticed for all BM-PANNM. Amidoximation increased COS-7 cell viability up to 82 %. The cell viability of 0.1Ag/Cu-PANNM, 0.3Ag/Cu-PANNM, and 0.5Ag/Cu-PANNM was found to be ∼68 %, ∼62, and 54 %, respectively. In LDH assay, almost no release of LDH was detected, suggesting the compatibility of the cell membrane in contact with BM-PANNM. The improved biocompatibility of BM-PANNM even at higher loading (%) of NPs must be ascribed to the controlled release of metal species in the early stage, antioxidant, and biocompatible lignin capping of NPs. ConclusionsBM-PANNM displayed superior antibacterial activity against E. coli and S. aureus bacterial strains and acceptable biocompatibility of COS-7 cells even at higher loading (%) of Ag/CuNPs. Our findings suggest that BM-PANNM can be used as a potential antibacterial wound dressing and other antibacterial applications where sustained antibacterial activity is needed.

Synthesis and Characterization of Silver Nanoparticles from the Leaf Stalk Extract of Moringa oleifera

The exploitation of plant extract as a reducing agent for synthetic silver nanoparticles has become the main focus of researchers. This study aimed to synthesize silver nanoparticles (AgNPs) from Moringa oleifera leaf stalk extract via bio-reduction. The AgNPs were characterized through ultraviolet-visible absorption spectroscopy (UV-Vis), Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The research results indicated that an increase in the initial AgNO3 concentration and incubation time had affected the absorption pattern of the surface plasmon resonance (SPR) trend of AgNPs. The results of the functional group analysis revealed the formation of the ketone group (1741 cm-1), which was derived from hydroxyl groups (3415 cm-1). The crystal structure of AgNPs was characterized using XRD. The estimation of the crystal measurement based on the Debye-Scherer equation was 15.59 nm, which was estimated as having a cube crystal form.

Dual-Action Effect of Gallium and Silver Providing Osseointegration and Antibacterial Properties to Calcium Titanate Coatings on Porous Titanium Implants.

Previously, functional coatings on 3D-printed titanium implants were developed to improve their biointegration by separately incorporating Ga and Ag on the biomaterial surface. Now, a thermochemical treatment modification is proposed to study the effect of their simultaneous incorporation. Different concentrations of AgNO3 and Ga(NO3)3 are evaluated, and the obtained surfaces are completely characterized. Ion release, cytotoxicity, and bioactivity studies complement the characterization. The provided antibacterial effect of the surfaces is analyzed, and cell response is assessed by the study of SaOS-2 cell adhesion, proliferation, and differentiation. The Ti surface doping is confirmed by the formation of Ga-containing Ca titanates and nanoparticles of metallic Ag within the titanate coating. The surfaces generated with all combinations of AgNO3 and Ga(NO3)3 concentrations show bioactivity. The bacterial assay confirms a strong bactericidal impact achieved by the effect of both Ga and Ag present on the surface, especially for Pseudomonas aeruginosa, one of the main pathogens involved in orthopedic implant failures. SaOS-2 cells adhere and proliferate on the Ga/Ag-doped Ti surfaces, and the presence of gallium favors cell differentiation. The dual effect of both metallic agents doping the titanium surface provides bioactivity while protecting the biomaterial from the most frequent pathogens in implantology.

Formation of silver halos by Sphingomonas paucimobilis MX8 and its bioleaching of silver from computer keyboard printed circuit boards.

Silver (Ag) is currently obtained from primary and secondary sources through hydrometallurgical and pyrometallurgical processes. However, these processes consume high amounts of energy and are environmentally unfriendly. The search for bacteria tolerant with a high leaching capacity for to Ag is therefore a necessary requirement as part of the development of bioleaching technologies with reduced impact on the environment and lower energy expenditure. In this sense, the objective of this research was to evaluate the tolerance of Sphingomonas paucimobilis MX8 to Ag added to nutrient agar, and to determine whether this tolerance could favor the bioleaching of Ag present on the printed circuit boards (PCBs) of computer keyboards. The bacteria Sphingomonas paucimobilis MX8 was cultured in Petri dishes with nutrient agar and four different concentrations of AgNO3 (200, 400, 600, and 800mg L-1) at 28°C for 10days. For the bioleaching experiment, the bacteria were grown in a mineral medium with computer keyboard PCBs for 30days at room temperature (17 to 22°C) and centrifugation at 150rpm. The results indicate that Sphingomonas paucimobilis MX8 is tolerant to Ag and forms a silvery halo around its growth in the presence of this metal. Furthermore, Sphingomonas paucimobilis MX8 was able to bioleach 12% of the Ag found in computer keyboard PCBs. The results obtained could help generate more environmentally friendly silver bioleaching processes in which the silver bioleaching capacity of this bacterium is increased.

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.

In-situ electrodeposited Ag/Cu for electrochemical reduction of acetic acid to nanodiamond under ambient conditions

Carbon nanostructured materials such as nanodiamonds and graphene are useful for various applications, but their low-energy production technologies remain an important challenge to overcome. Herein, the electrochemical reduction of acetic acid using in-situ electrodeposited Ag/Cu to nanocrystalline carbon products was investigated as a function of AgNO3 concentrations in the presence of water and [BMIM]+[BF4]- ionic liquid. Under the conditions used, the deposited Ag clusters could become negatively charged and were responsible for the reduction of acetic acid and the consequent crystalline carbon growth. Increasing Ag concentrations did not only result in higher amounts of Ag being deposited but also created significant local pressure on the atomistic level, where the crystalline carbon was formed, resulting in the re-ordering of carbon atoms into nanodiamond structure. The presence of nanodiamond with average crystallite size 27 nm was clearly evidenced by XRD, Raman, XPS, and TEM-EDX-SAED. The in-situ electrochemical reduction has shown to be an effective ultra-low energy strategy to produce crystalline solid carbon under ambient conditions.

Green synthesis of silver nanoparticles using hydroalcoholic root extract of Potentilla fulgens and evaluation of its cutaneous wound healing potential

The present study focuses on the green synthesis of silver nanoparticles (AgNPs) using hydro-alcoholic root extract of Potentilla fulgens and evaluation of its wound healing properties in the rat model. The dried roots of PF were refluxed in alcohol: water mixture (70:30) for 24 h and the extract were evaporated to dryness using a rotary evaporator. For the synthesis of AgNP-PF, different concentrations of the extract (1–5 mg) were allowed to react with different concentrations of silver nitrate (1–5 mM). The completion of the reaction was noted through color change from colorless to brown and this can be further confirmed using UV–visible spectroscopy. The optimized formulation was further characterized using DLS, TEM, EDX, FTIR, and XRD. The biosynthesized AgNP-PF were loaded into a topical carbopol gel and finally investigated for wound healing potential in experimental rats. Results revealed that the ratio of different concentrations of AgNO3 to plant extract significantly affected the particle size, shape, yield and stability of the AgNP-PF. A UV–visible absorption band of 410–440 nm indicated the synthesis of AgNP-PF. TEM data with a size range of 10–20 nm showed that the AgNP-PF were spherical in shape. FTIR revealed the presence of -OH group responsible for the reduction and stabilization, while XRD confirmed the crystallinity of the AgNP-PF. Topical AgNP-PF gel showed promising wound healing property with significant wound contraction in experimental rats. In conclusion, stable silver nanoparticles were successfully formulated by green synthesis and loaded efficiently for efficient wound healing.

Green biosynthesis, characterization of silver nanoparticles using a green alga Spirogyra sp., and their antioxidant and enzyme activities

A simple, environmentally friendly, inexpensive, and one-step alternative method was reported for the green biosynthesis of silver nanoparticles (AgNPs) operating the Spirogyra sp. extract as a reducing and stabilizing substance. Concentration of AgNO3 and reaction time were optimized to prepare AgNPs under controlled conditions. The synthesized silver nanoparticles were characterized by UV-Vis absorption spectroscopy, fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and elemental mapping. The TEM analysis showed that the average particle size of AgNPs was 18.3 nm. Structural details of silver nanoparticles elucidated by Selected Area Electron Diffraction (SAED) based on TEM images. In addition, biological activity tests were applied to nanoparticles and algal extracts to determine antioxidant activity (3 different tests: DPPH (1,1-diphenyl-2-picrylhydrazil) radical scavenging activity, total phenolic content (TPC) and total flavonoid content (TFC)) and α-glucosidase enzyme inhibition. Antioxidant activity and α-glucosidase enzyme inhibition values of silver nanoparticles are higher than the values of Spirogyra sp. extracts.

Superhydrophobic PDMS/PPy-Ag/Graphene/PET films with highly efficient electromagnetic interference shielding, UV shielding, self-cleaning and electrothermal deicing

In this work, a general strategy is reported to fabricate flexible superhydrophobic PDMS/PPy-Ag/Graphene/PET films with high conductivity and durability. The films achieved surface resistance of 6.32 Ω/□ and superhydrophobicity of 154.5° through adjusting AgNO3 concentration and reaction time. With the increase of reaction time, surface micro/nanostructure of the film became dense and the pores decreased to disappear, leading to competition between superhydrophobicity and electrical conductivity. The film had excellent heat resistance and UV resistance, good mechanical stability for sandpaper abrasion. The films could keep superhydrophobicity even they are treated with acid, alkali and salt solutions. Importantly, the coating showed excellent and stable electrothermal performance with fast response speed and rapid electrothermal deicing ability. At 5 V, ice cube with 0.5 cm3 completely melted and slid in 160 s. The films also showed excellent self-cleaning, UV shielding and electromagnetic interference shielding with an EMI SET of about 31.5 dB.