Ag Ions Research Articles

Argentophilic Interactions, Flexibility, and Dynamics of Pyrrole Cages Encapsulating Silver(I) Clusters.

Recently, pyrrole cages have been synthesized that encapsulate ion pairs and silver(I) clusters to form intricate supramolecular capsules. We report here a computational analysis of these structures using density functional theory combined with a semiempirical tight-binding approach. We find that for neutral pyrrole cages, the Gibbs free energies of formation provide reliable predictions for the ratio of bound ions. For charged pyrrole cages, we find strong argentophilic interactions between Ag ions on the basis of the calculated bond indices and molecular orbitals. For the cage with the Ag4 cluster, we find two minimum-geometry conformations that differ by only 6.5 kcal/mol, with an energy barrier <1 kcal/mol, suggesting a very flexible structure as indicated by molecular dynamics. The predicted energies of formation of [Agn⊂1]n-3+ (n = 1-5) cryptands provide low energy barriers of formation of 5-20 kcal/mol for all cases, which is consistent with the experimental data. Furthermore, we also examined the structural variability of mixed-valence silver clusters to test whether additional geometrical conformations inside the organic cage are thermodynamically accessible. In this context, we show that the time-dependent density functional theory UV-vis spectra may potentially serve as a diagnostic probe to characterize mixed-valence and geometrical configurations of silver clusters encapsulated into cryptands.

Gas-Solid Phase Reaction Derived Silver Bismuth Iodide Rudorffite: Structural Insight and Exploring Photocatalytic Potential of CO2 Reduction.

Photocatalytic reduction of CO2 is a promising strategy to mitigate the effects of global warming by converting CO2 into valuable energy-dense products. Silver bismuth iodide (SBI) is an attractive material owing to its tunable bandgap and favorable band-edge positions for efficient CO2 photoreduction. In this study, SBI materials, including AgBi2I7, AgBiI4, Ag2BiI5, and Ag3BiI6 are first synthesized, through gas-solid reaction by controlling the stoichiometric ratio of reactants. The X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) results revealed that the distance between Ag-I is proportional to the degree of Ag ions delocalization, which occupies the vacant sites. That greatly retards the charge recombination at vacant sites. In addition, the surface potential via photo-assisted Kelvin probe force measurements of various SBI catalysts shows that Ag3BiI6 exhibits the highest surface potential change due to the rich delocalized Ag ions. This results in effective charge carrier transport and prevention of charge recombination at vacant sites. Taking the above advantages, the averaged CO and CH4 production rates for Ag3BiI6 achieved 0.23 and 0.10µmolg-1h-1, respectively. The findings suggest that Ag3BiI6 has a high potential as a novel photocatalyst for CO2 reduction and sheds light on the possibility of solving environmental contamination and sustainable energy crises.

Salivary and urinary assessment of fluoride and silver ion concentrations after silver diamine fluoride application in children: a prospective cohort study.

The purpose of the study was to determine the fluoride (F) and silver (Ag) ions levels in the saliva and urine of healthy children after silver diamine fluoride (SDF) application on dental carious lesions. Sixty children (4-6years with ≥ 3 caries lesions) were recruited from the outpatient department of Pediatric Dentistry. From each child, 3ml unstimulated saliva samples were collected at baseline, one hour, and 24h after SDF application. Similarly, 3ml urine samples were collected prior to and after 24h of SDF application. F and Ag ion concentrations were determined by fluoride ion-selective electrode (ISE) and inductively coupled plasma mass spectrometry (ICPMS), respectively. The mean ± standard deviation (SD) baseline, 1-h, and 24-h salivary F concentrations (ppm) were 0.07 ± 0.07, 0.93 ± 0.48, and 0.19 ± 0.19, respectively, while the mean baseline and 24-h urinary F concentrations (ppm) were 0.33 ± 0.20ppm and 0.43 ± 0.25ppm, respectively. The mean baseline, 1-h, and 24-h salivary Ag concentrations (ppb) were 4.22 ± 3.15, 4198 ± 350, and 56.93 ± 37, respectively. The mean baseline and 24-h urinary Ag concentrations (ppb) were 2.80 ± 2.93ppb and 4.72 ± 4.0ppb, respectively. There were statistically elevated F and Ag ion concentrations at 1h and 24h after SDF application as compared to the baseline. Salivary and urinary F and Ag ions concentrations elevated significantly at 24h following SDF applications in children. A significant high recovery of these ions in urine indicates minimal systemic absorption, thus intermittent topical application of 38% SDF has a minimal risk of toxicity.

Statistical optimization for greener synthesis of multi-efficient silver nanoparticles from the Hypocrea lixii GGRK4 culture filtrate and their ecofriendly applications

The culture filtrate of Hypocrea lixii GGRK4 played a vital role as a reducing and stabilizing agent in the mycosynthesis of silver nanoparticles (AgNPs) using silver nitrate (AgNO3). The extracellular extract derived from fungi emerged as a noteworthy option for synthesizing AgNPs due to its potential composition of metabolites, including enzymes and other bioactive substances. Hence, the presence of a dark brown color serves as a key indicator for the biosynthesis of AgNPs through the reduction of Ag (I) ions to Ag by the fungal culture filtrate. To facilitate the synthesis of AgNPs, a combination of hybrid technologies, specifically the “one factor at a time” approach and statistical tools such as response surface methodology, was used using a face-centered central composite design (FCCCD). Utilizing a modified CX medium with pH of 5.02 supported the fungi synthesizing AgNPs at a temperature of 30°C. The multi-efficient AgNPs were characterized through various techniques, including UV–visible spectrophotometry, zeta size and potential analysis using a zeta size analyzer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and fluorescence spectroscopy. The biosynthesized AgNPs have significant associated functional groups, revealed by FTIR analysis. TEM histogram analysis showed that these multi-efficient AgNPs have a size of 17.34 nm. Similarly, they have emission and excitation spectra of 450 nm and 390 nm, respectively, revealed by fluorescence spectrum analysis. Compared to the standard, the biosynthesized AgNPs have significant antibacterial and free radical scavenging properties and dye degradation capability. Additionally, the half-maximal inhibitory concentration (IC50) value was found statistically significant based on t-test analysis. Finally, the biosynthesized AgNPs could be used in potential applications encompassing ecofriendly degradation, antimicrobial activity, and therapeutic applications, such as free radical scavenging properties.

Modification induced by 120 MeV Ag ion irradiation in ZnS

We report the structural, morphological, and optical properties of ZnS thin films before and after swift heavy ion (SHI) irradiation of 120 MeV Ag ions. These films were deposited by the spin coating method on the glass substrate and irradiated at various ion fluencies from 1 × 1011 to 1 × 1013 ions/cm2. The Grazing Incidence X-ray diffraction (GIXRD), Scanning electron microscopy (SEM), UV–visible transmittance, Photoluminescence (PL), and Raman Spectroscopy were used to characterize these ZnS thin films. The GIXRD patterns show a mixed phase of cubic and hexagonal structure after the ion irradiation. The crystallite sizes of pure and irradiated films are significantly modified. Raman spectroscopy shows a slight increase in the intensity of the 3LO mode of ZnS on irradiation. The SEM image shows nanoflake-like structures in pristine, and the irradiated thin films depict various morphologies (rod, platy, and sphere-like). UV–visible shows a cut-off wavelength at 339 nm and the spectra are blue-shifted with the increase in ion fluence. The Tauc plots reveal the increase in the band gap. The intensity of PL decreases with ion irradiation. Hence the analytical results show that the structural and optical properties of ZnS thin films are altered on swift heavy ion irradiation which may have potential applications in optoelectronic applications.

A transformative oxidation process involving silver-based catalysis of para aminobenzyl alcohol for transposing a pollutant into a resource

ABSTRACT A kinetic-spectrophotometric method has been devised to analyze the oxidation reaction of Para-aminobenzyl alcohol [PABAlc] catalyzed by Ag (I). PABAlc is used in numerous fields of pharmaceutical and medicinal chemistry as intermediates. The harmful effects of PABAlc cannot be overlooked in spite of its manifold applications. The toxicity of PABAlc may lead to allergic reactions, serious eye damage, respiratory tract infections amongst few. It became utmost important to formulate a method to establish the presence of PABAlc in a particular sample of water in order to circumvent its proximity to common people. In our work, we have provided an insight to an oxidation process using PABAlc as substrate catalyzed by Ag (I) ions besides proposing a reaction mechanism of the reaction under study with substantial data in the form of different thermodynamic parameters like activation energy (55 kJ/mol−1), temperature coefficient (1.92), enthalpy of activation (52.89 kJ/mol−1), alongside deets related to various effects of oxidant, substrate, catalyst, temperature, pH, ionic strength, and so on, on reaction kinetics. Additionally, the product formed in the proposed mechanism has its commercial importance in the field of pharmacy, dyes, and so on, sufficient enough to put forward a rationale for the investigations.

Disorder induced in GaN thin films by 200 MeV silver ions

GaN is a material of strategic importance due to its versatility in high temperature, radiation prone and chemical environments. The present study explores evolution of defects in GaN thin films in swift heavy ion radiation regime. GaN thin films grown by metal organic chemical vapour deposition techniques were irradiated with 200 MeV Ag ions at various fluences starting from 5 × 1010 to 5 × 1012 ions/cm2. Structural analysis revealed accumulation of lattice damage with increasing fluence. XRD analysis reveals that swift heavy ions of silver (Ag) deposit more energy into the target lattice, inducing localized damage at higher fluences, leading to broader peaks in irradiated samples. Recrystallization becomes evident at fluences of 1 × 1011 ions/cm2 of Ag 200 MeV ion irradiation, as indicated by a decrease in Full Width at Half Maximum (FWHM). The compressive stress identified in Raman analysis is associated with the c-axis and elevates the wavenumber of the E2(H) mode following Ag ion irradiation. Meanwhile, the pristine sample exhibits narrow A1 (LO) phonon mode peaks, indicating good crystallinity. Photoluminescence investigations demonstrate that Ag ions induce point defects in GaN, evident through analysis of YL, GL, and BL defect-related emission peaks following irradiation at various fluences.

Immobilization of Silver(I) Ions on Amino-Functionalized Chromium(III) Terephthalate with Organophosphine and its C-H Carboxylation of a Heteroaromatic Compound.

A newly designed heterogenized catalyst that incorporates silver(I) ions with 2-(dicyclohexylphosphaneyl)acetaldehyde (PCy2 aldehyde) into amino-functionalized chromium(III) terephthalate is developed. Silver(I) ions were robustly immobilized on the amino-functionalized chromium(III) terephthalate, which contains an imine bond formed by the reaction with PCy2 aldehyde. The Ag(I) ion is coordinated with the phosphine in the imine group to create MIL-101-AP(Ag). Characterizations were carefully carried out according to the synthetic steps. The catalytic performance of MIL-101-AP(Ag) was evaluated through the C-H carboxylation of thiophene-2-carbonitrile, achieving a 10 % yield with a turnover number of 1.0. The recyclability of the MIL-101-AP(Ag) catalyst was successfully demonstrated with five cycle, with no loss in activity and selectivity observed. This approach, which involves the formation of an imine bond to facilitate silver loading with phosphine on amino-functionalized MIL-101(Cr), exhibits significant potential for both CO2 fixation and C-H carboxylation, thereby highlighting the modified material's promise as a sustainable catalyst.

Synthesis and catalytic properties of highly porous Ag-Rh nanocages

Ag-Rh nanocages are synthesised by a facile method at 190 °C using Ag nanocubes and Na3RhCl6 as sacrificial templates and precursor, respectively. Upon introduction of Na3RhCl6 into Ag nanocube suspension in ethylene glycol (EG) with poly(vinylpyrrolidone), Rh(III) ions are reduced by EG and Ag atoms via galvanic reaction; simultaneously, the released Ag(I) ions are reduced by EG. The reduction and co-deposition of both Ag and Rh atoms result in the formation of highly porous Ag-Rh nanocages when high volume of Na3RhCl6 is introduced. The Ag-Rh nanocages with Ag:Rh atomic ratio of 54.2:45.8 exhibit good catalytic activity toward the degradation of rhodamine 6G, reduction of 4-nitrophenol, and decomposition of hydrazine.

Gamma radiation synthesis of hydroxyethyl cellulose/acrylic acid/CYANEX 471X hydrogel for silver ions capture from acidic nitrate medium

The current novelty in this study is to recover silver ion with selective extractant such as cyanex 471X (triisobutylphosphine sulfide) through a clean and green method with high efficiency. Herein, a sustainable hydrogel (HEC/AAc/CX3) was fabricated from triisobutylphosphine sulfide, hydroxyethyl cellulose (HEC), and acrylic acid (AAc) using gamma irradiation polymerization and implanted for the sorption of silver Ag (I) ions from a nitrate acidic medium. Different techniques were employed for characterization of HEC/AAc/CX3 hydrogel such as FT-IR, SEM, XRD, and EDX, before and after the sorption process of Ag(I) ions. Gel content and swelling kinetics ratio of hydrogels at different irradiation doses (10, 20, 30, 40, and 50 kGy) were studied. The Fickian diffusion model results indicate that HEC/AAc/CX3 hydrogel is non-Fickian diffusion, which confirmed that the diffusion and relaxation rates are compatible and were selected for further sorption of Ag(I). The irradiated HEC/AAc/CX3 hydrogels, which contain 0.1 g of cyanex 471X, were employed for batch sorption of 100 mg/L Ag(I) from an acidic solution, and the suggested conditions were pH = 1, time = 60, and v/m = 0.05 L/g, which gives a sorption percentage of 75%. The values of thermodynamic parameters ΔH, ΔG, and ΔS were evaluated as—62.80 kJ/mol, 5 kJ/mol, and -227 J/mol, which indicate that the sorption system was exothermic and nonspontaneous in nature. The maximum adsorption capacity of irradiated HEC/AAc/CX3 for Ag(I) was found to be 12 mg. g−1 at 298 K. Furthermore, the maximum desorption percent of Ag ions from HEC/AAc/CX3 was found to be 70% and achieved with 0.5 M NH4SCN after one desorption cycle. The prepared hydrogel proved its selectivity towards silver ions with facile desorption steps and reusability cycles.Graphical

The role of Ag ions incorporation on the Magnetic, and Antimicrobial Properties of NiO Nanoparticles

Ni1-xAgxO nanoparticles (NPs) with x = 0.00, 0.02, 0.04, 0.06, and 0.08) were fabricated using the composite hydroxide mediated (CHM) method. The effects of Ag doping on the structural, magnetic, and antimicrobial characteristics of NiO NPs have been reported. The stretching mode of the Ni–O molecules was identified at 443 cm−1 in the Fourier transform infrared spectra. The aggregation of nanoparticles with different sizes and shapes is seen under transmission and scanning electron microscopes. The blocking temperature (TB) peak in zero-field cooled (ZFC) magnetization curves display the magnetization from the core of NPs. This peak is absent for the samples with x=0.00 and 0.02, which show instead a small net magnetization from the antiferromagnetic core of these NPs. However, a TB peak was found for the samples with x=0.04,0.06and0.08, at 22, 72, and 65 K, respectively, which indicates that the magnetization is induced from the AFM core of NiO NPs for higher Ag doping. With an increasing concentration of Ag in the NiO NPs, the net magnetization did increase and a maximum was found for x = 0.04 at 300 K. For a higher doping concentration of 8 % Ag, a sharp decrease in magnetization was observed. Furthermore, the efficacy and synergistic effect of Ag doping had been analyzed for the effective improvement of the antibacterial properties of NiO NPs. Pure and Ag-doped NiO NPs were exploited to assess their anti-microbial activity against Enterobacter sp., E. coli, P. aeruginosa, and S. pyrogens. The study revealed that anti-bacterial or anti-biofouling properties were introduced as an additional attribute to NiO NPs by incorporation of Ag ions due to its inherent nature as an antimicrobial agent and enhanced its capability to sterilize microbial pathogens.

Evaluation of antifungal activity of visible light-activated doped TiO2 nanoparticles.

Titanium dioxide (TiO2) is a well-known material for its biomedical applications, among which its implementation as a photosensitizer in photodynamic therapy has attracted considerable interest due to its photocatalytic properties, biocompatibility, high chemical stability, and low toxicity. However, the photoactivation of TiO2 requires ultraviolet light, which may lead to cell mutation and consequently cancer. To address these challenges, recent research has focused on the incorporation of metal dopants into the TiO2 lattice to shift the band gap to lower energies by introducing allowed energy states within the band gap, thus ensuring the harnessing of visible light. This study presents the synthesis, characterization, and application of TiO2 nanoparticles (NPs) in their undoped, doped, and co-doped forms for antimicrobial photodynamic therapy (APDT) against Candida albicans. Blue light with a wavelength of 450nm was used, with doses ranging from 20 to 60J/cm2 and an NP concentration of 500µg/ml. It was observed that doping TiO2 with Cu, Fe, Ag ions, and co-doping Cu:Fe into the TiO2 nanostructure enhanced the visible light photoactivity of TiO2 NPs. Experimental studies were done to investigate the effects of different ions doped into the TiO2 crystal lattice on their structural, optical, morphological, and chemical composition for APDT applications. In particular, Ag-doped TiO2 emerged as the best candidate, achieving 90-100% eradication of C. albicans.

A novel green synthesis of MnO2-Coal composite for rapid removal of silver and lead from wastewater

The presence of Ag(I) and Pb(II) ions in wastewater poses a significant threat to human health in contemporary times. This study aims to explore the development of a novel and economical adsorbent by grafting MnO2 particles onto low-rank coal, providing an innovative solution for the remediation of water contaminated with silver and lead. The synthesized nanocomposites, referred to as MnO2-Coal, underwent thorough characterization using FTIR, XRD, BET, and SEM to highlight the feasibility of in-situ surface modification of coal with MnO2 nanoparticles. The adsorption of Ag(I) and Pb(II) from their respective aqueous solution onto MnO2-Coal was systematically investigated, with optimization of key parameters such as pH, temperature, initial concentration, contact time, ionic strength, and competing ions. Remarkably adsorption equilibrium was achieved within a 10 min, resulting in impressive removal rates of 80–90 % for both Ag(I) and Pb(II) at pH 6. The experimental data were evaluated using Langmuir, Freundlich, and Temkin isotherm models. The Langmuir isotherm model proved to be more accurate in representing the adsorption of Ag(I) and Pb(II) ions onto MnO2-Coal, exhibiting high regression coefficients (R2 = 0.99) and maximum adsorption capacities of 93.57 and 61.98 mg/g, along with partition coefficients of 4.53 and 71.92 L/g for Ag(I) and Pb(II), respectively, at 293 K. Kinetic assessments employing PFO, PSO, Elovich, and IPD models indicated that the PFO and PSO models were most suitable for adsorption mechanism of Pb(II) and Ag(I) on MnO2-Coal composites, respectively. Moreover, thermodynamic evaluation revealed the spontaneous and endothermic adsorption process for Ag(I), while exothermic behavior for adsorption of Pb(II). Importantly, this approach not only demonstrates cost-effectiveness but also environmental friendliness in treating heavy metal-contamination in water. The research suggests the potential of MnO2-Coal composites as efficient and sustainable adsorbents for water purification applications.

Ag(I) Ion-Concentration-Dependent Dynamic Mechanism of Thiolactic-Acid-Capped Gold Nanoclusters Revealed by Fluorescence Spectra and Two-Dimensional Correlation Spectroscopy.

Based on fluorescence spectroscopy, being combined with several spectral analysis techniques including principal component analysis (PCA), two-dimensional correlation spectroscopy (2D-COS), and moving window 2D-COS, the study disclosed the structural variations of gold nanoclusters capped by thiolactic acid (AuNCs@TLA) induced by Ag(I) ions. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were applied to monitor the morphology evolution of the surface and composition of the nanoclusters induced by Ag(I) ions. Several spectral components, centered at (790, 607) nm, (670, 590) nm, and (740, 670) nm were revealed by 2D-COS analysis, suggesting new luminescent species or groups were generated with the introduction of Ag(I) ions. A two-stage mechanism was revealed for the photoluminescence variations of AuNCs@TLA induced by Ag(I) ion. The first stage was characterized by the emission quench of 790 nm followed by the emerging emission of 607 nm, which was attributed to the anti-galvanic reaction; and the second stage featured by the noticeable growth of the emission's intensity around 670 nm as result of the AuNCs' size effect. The present study will attract more focuses on near-infrared (NIR)-emitted metal nanoclusters and promote their synthesis and utilities.

Bacterial nanocellulose (BNC) biosynthesis by Komagataeibacter hansenii RM-03 using agricultural waste as substrates and BNC-silver nanocomposite preparation

Bacterial nanocellulose (BNC) is a remarkable biopolymer synthesised by bacterium, exhibiting exceptional properties. However, conventional Hestrin-Schramm (HS) medium, particularly the carbon source, poses challenges of high costs and low productivity. This study explores BNC biosynthesis on a modified HS medium, employing agricultural wastes (sugarcane molasses, banana peel, and pineapple peel) as carbon sources, and compares the overall yield of BNC produced. Sugarcane molasses proved to be the most effective, yielding the highest BNC concentration (8.19 g/L) after 7 days, followed by pineapple peel (2.16 g/L) and banana peel (2.11 g/L). Extensive research was conducted to enhance properties of BNC by an environmentally friendly approach, incorporating silver nanoparticles (AgNP) utilising Momordica charantia fruit extract, resulting in a BNC-Ag nanocomposite. The synthesis involved mixing 1 mM silver nitrate (AgNO3) with 15 mL of M. charantia fruit extract to reduce Ag ions to AgNP, which was confirmed by UV-vis spectroscopy with an absorbance peak between 400 and 410 nm. Characterisation using FESEM and TEM on the synthesized BNC showed minimal impact on BNC fiber diameter from waste-derived carbon sources. XRD indicated slight variations in crystallinity index, with the highest (85%) in TSM-derived BNC. FTIR analysis revealed similar chemical profiles across all BNC, indicating cellulose formation. The BNC-Ag nanocomposite exhibited potent antibacterial activity against multi-drug resistant strains (Pseudomonas aeruginosa, Salmonella typhi, Bacillus subtilis, Staphylococcus aureus) through disc diffusion method with inhibition zones up to 16.8 mm. Overall, the findings from this study contribute to the development of environmentally sustainable for the production of functional BNC materials with enhanced properties for diverse applications.

Double perovskite oxides Ba2-xAgxFeMoO6 (x = 0.0, 0.025, 0.05)

Double perovskite Ba2FeMoO6 (BFMO) substituted with monovalent Ag ions was synthesized using the sol-gel method, and its structure and magnetic properties were systematically studied. Rietveld refinement showed that the samples had a single phase with a cubic structure and an Fm-3m space group. With Ag substitution, the lattice parameter and unit cell of BFMO increased linearly, and the morphology of the samples was altered. X-ray photoelectron spectroscopy (XPS) examination showed mixed valence in the sample with x = 0.025 due to the Ag doping. The doped samples exhibited a decrease in magnetization, an increase in transition temperature, and anti-site (AS) defects. The AC magnetic susceptibility of the sample with x = 0.025 showed two peaks attributed to the two critical temperatures.

Synthesis and dosimetric characterization of lithium tetraborate (Li2B4O7:Cu,Ag) thermoluminescent dosimeter with improved reproducibility and reusability

A nano-sized, tissue equivalent, polycrystalline Li2B4O7:Cu, Ag phosphor was synthesized for dosimetric applications. Repeated annealing, irradiation and readouts may alter the color and affect the sensitivity of the phosphor. One of the aims of the present work was to dope Li2B4O7 with an appropriate amount of Ag and Cu atoms in order to diminish such effects and consequently improve reproducibility and reusability of the dosimeter. For this purpose, Li2B4O7 was primarily doped with Ag ions, and the Cu atoms were introduced with minimal concetration. A sample co-doped with 0.35 wt% Ag and 0.015 wt% Cu exhibited optimum TL response. To facilitate handling of the material, the powdered sample was also reproduced in pellet form. Linear integrated TL response was observed from 1 mGy to 20 Gy. No change in material's sensitivity and color was observed after repeated annealing, irradiation and readout episodes. Response of the material was found to be reproducible with a COV between 1.7 and 2.3%. Thermal quenching effects with increasing heating rate were seen for the current material. Less than 5% fading was observed during a two month study. The obtained glow curve was very simple having a main dosimetric peak at about 200 ± 10 °C with two small shoulder peaks. Kinetic analysis of the glow curve was performed by an experimental method (Tm-Tstop) and by curve fitting approximation. Kinetic parameters (b, s and E) were found within the prescribed limits. The promising dosimetric characteristics and the optimal glow curve favours this new material for use as a field dosimeter.

Activity of Bambusa vulgaris extract in reducing silver nanoparticles: evaluation against methylene blue organic pollutant and microbial agents

This article presents an investigation focusing on successfully synthesising silver nanoparticles with zero valences. The synthesis involves utilising an extract from bamboo leaves, specifically those obtained from the Bambusa vulgaris species. X-ray diffraction, transmission electron microscopy, Fourier transform infrared, and ultraviolet–visible spectroscopy characterised the synthesised Ag nanomaterials. The X-ray diffraction pattern obtained from the collected samples confirms the presence of a face-centred cubic structure and a significant level of crystallinity. The studied materials had a spherical morphology, as determined by transmission electron microscopy analysis. The particle size was measured to be 22 nm. FT-IR analysis validates the presence of biomolecules in the leaf extract, which is accountable for the reduction of Ag+ ions and subsequent stabilisation of Ag nanoparticles. Without chemical agents, the reduction of Ag ions to Ag was confirmed using UV–Vis spectroscopy. This analytical technique revealed a peak at 450 nm, indicating surface plasmon resonance. Photogenerated electron carriers can be inferred from a distinct and diverse set of photoluminescence spectra. The study also includes an analysis of the photocatalytic effectiveness of the synthesised silver nanoparticles, specifically in the breakdown of methylene blue (MB) dye. The efficacy of the silver nanoparticle (Ag NP) photocatalyst was assessed by examining the degradation process of a methylene blue dye solution in an aqueous medium under direct sunlight exposure. The experiment also evaluated the impact of catalyst dosage and dye concentration on the efficient degradation of MB dye. The investigation findings indicate that the optimal catalyst dosage and dye concentration were determined to be 0.015 mg/mL and 10 µM, respectively. Notably, the photocatalytic degradation process exhibited remarkable efficacy, with a peak efficiency of 94% after 120 min under direct solar irradiation. The experimental results suggest that the synthesised particles demonstrate a disintegration rate of 96% over 120 min when exposed to visible light. The utilisation of bio-processed silver nanoparticles has exhibited the achievement of phase purity during the manufacturing process, as well as an enhancement in catalytic efficacy. It implies that the synthesised technique offers a more advantageous option for producing nanoparticles on a large scale, potentially applicable in wastewater treatment at a broad level.

Wound Dressing Based on Silver Nanoparticle Embedded Wool Keratin Electrospun Nanofibers Deposited on Cotton Fabric: Preparation, Characterization, Antimicrobial Activity, and Cytocompatibility.

Wool keratin (WK) protein is attractive for wound dressing and biomedical applications due to its excellent biodegradability, cytocompatibility, and wound-healing properties. In this work, WK-based wound dressings were prepared by depositing WK/poly(vinyl alcohol) (PVA) and silver nanoparticle (Ag NP)-embedded WK/PVA composite nanofibrous membranes on cotton fabrics by electrospinning. Ag NPs were biosynthesized by reduction and stabilization with sodium alginate. The formed Ag NPs were characterized by ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy, and their size was determined by transmission electron microscopy and image analysis. The formed Ag NPs were spherical and had an average diameter of 9.95 nm. The produced Ag NP-embedded WK/PVA composite nanofiber-deposited cotton fabric surface was characterized by FTIR and dynamic contact angle measurements, and the nanofiber morphologies were characterized by scanning electron microscopy. The average diameter of the nanofibers formed by 0.1% Ag NP-embedded WK/PVA solution was 146.7 nm. The antibacterial activity of the surface of cotton fabrics coated with electrospun composite nanofibers was evaluated against the two most common wound-causing pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. The cotton fabric coated with 0.1% Ag NP-embedded WK/PVA nanofibers showed very good antibacterial activity against both pathogens, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay results showed good cytocompatibility against L-929 mouse fibroblast cells. However, the increase in Ag NP content in the nanofibers to 0.2% negatively affected the cell viability due to the high release rate of Ag ions. The results achieved show that the developed wound dressing has good potential for wound healing applications.

Synergistically Modulating Conductive Filaments in Ion-Based Memristors for Enhanced Analog In-Memory Computing.

Memristors offer a promising solution to address the performance and energy challenges faced by conventional von Neumann computer systems. Yet, stochastic ion migration in conductive filament often leads to an undesired performance tradeoff between memory window, retention, and endurance. Herein, a robust memristor based on oxygen-rich SnO2 nanoflowers switching medium, enabled by seed-mediated wet chemistry, to overcome the ion migration issue for enhanced analog in-memory computing is reported. Notably, the interplay between the oxygen vacancy (Vo) and Ag ions (Ag+) in the Ag/SnO2/p++-Si memristor can efficiently modulate the formation and abruption of conductive filaments, thereby resulting in a high on/off ratio (>106), long memory retention (10-year extrapolation), and low switching variability (SV = 6.85%). Multiple synaptic functions, such as paired-pulse facilitation, long-term potentiation/depression, and spike-time dependent plasticity, are demonstrated. Finally, facilitated by the symmetric analog weight updating and multiple conductance states, a high image recognition accuracy of ≥ 91.39% is achieved, substantiating its feasibility for analog in-memory computing. This study highlights the significance of synergistically modulating conductive filaments in optimizing performance trade-offs, balancing memory window, retention, and endurance, which demonstrates techniques for regulating ion migration, rendering them a promising approach for enabling cutting-edge neuromorphic applications.