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The antimicrobial property of core-shell silver nanoparticles (Ag@mSiO 2) is better than that of yolk-shell silver nanoparticles (Ag@YSiO 2), which plays a protective role in silk cultural relics without interference. [Display omitted] Silver nanoparticles coated with organic-inorganic hybrid silica or inorganic silica have antimicrobial ability, and the coating can also effectively improve the dispersion and stability of the particles. The slow release of silver ions (Ag+) can improve the antimicrobial activity of silver nanoparticles. The synthesized nanoparticles are light yellow, which does not affect the look and feel of the silk cultural relics and meets the requirements of the principle of minimum interference. Two kinds of silver-based nanoparticles were synthesized: silver core-shell nanoparticle (Ag@mSiO 2) and silver yolk-shell nanoparticle (Ag@YSiO 2). The morphology, surface properties and Ag+ release efficiency of two nanoparticles were characterized. The antimicrobial effects of two nanoparticles on Aspergillus niger (A. niger) and Penicillium citrinum (P. citrinum) were compared. Both of Ag@mSiO 2 and Ag@YSiO 2 had uniform size and good stability. Two nanoparticles had pore structure and silver nanocore, which provided the basis for the dissolution and exchange of Ag+. Because more silver ions were released, Ag@mSiO 2 had higher antimicrobial activity than Ag@YSiO 2 for A. niger and P. citrinum. For various silk samples, Ag@mSiO 2 exhibited excellent antimicrobial properties. Meanwhile, there was little change in the color and tearing strength of Ag@mSiO 2 coated silk. [ABSTRACT FROM AUTHOR]

Silver recovery from sustainable sources such as seawater and e‐waste is critical for the conservation of land‐based resources and the reduction of the environmental impacts of e‐waste disposal. However, the abundance of competing metal ions in seawater and in e‐waste makes the recovery extremely challenging. Thus, to effectively capture silver ions under these conditions, the designing of materials with high selectivity, sufficient binding sites, and low affinity to competing metal ions is vital. Herein, we report the design and synthesis of a 3D‐like Schiff‐bridging crown‐based material named AC5, for the selective recovery of Ag+ ions. Through this design, a significant enhancement in the silver ion recovery was achieved with an excellent removal efficiency of up to 99.9%, and a tremendous increase in selectivity of 400 000 – 900 000% when compared to the metal ions (Li+, Na+, K+, Mg2+, and Ca2+) found in seawater, and the heavy metal ions (Cu2+, Cd2+, Ni2+, and Pb2+) found in electronic wastes. Density functional theory and molceular dynamics simulations revealed that the structural geometry of AC5 favors high charge transfer, lowered global hardness, and enhanced ion‐dipole attractions toward Ag+ ions, making the material an excellent candidate for the efficient recovery of silver from desalination brine and spent silver resources. [ABSTRACT FROM AUTHOR]

The transmission of bacteria and respiratory viruses through expelled saliva microdroplets and aerosols is a significant concern for healthcare workers, further highlighted during the SARS-CoV-2 pandemic. To address this issue, the development of nanomaterials with antimicrobial properties for use as nanolayers in respiratory protection equipment, such as facemasks or respirators, has emerged as a potential solution. In this study, a silver and copper nanolayer called SakCu® was deposited on one side of a spun-bond polypropylene fabric using the magnetron sputtering technique. The antibacterial and antiviral activity of the AgCu nanolayer was evaluated against droplets falling on the material and aerosols passing through it. The effectiveness of the nanolayer was assessed by measuring viral loads of the enveloped virus SARS-CoV-2 and viability assays using respiratory surrogate viruses, including PaMx54, PaMx60, PaMx61 (ssRNA, Leviviridae), and PhiX174 (ssDNA, Microviridae) as representatives of non-enveloped viruses. Colony forming unit (CFU) determination was employed to evaluate the survival of aerobic and anaerobic bacteria. The results demonstrated a nearly exponential reduction in SARS-CoV-2 viral load, achieving complete viral load reduction after 24 hours of contact incubation with the AgCu nanolayer. Viability assays with the surrogate viruses showed a significant reduction in viral replication between 2–4 hours after contact. The simulated viral filtration system demonstrated inhibition of viral replication ranging from 39% to 64%. The viability assays with PhiX174 exhibited a 2-log reduction in viral replication after 24 hours of contact and a 16.31% inhibition in viral filtration assays. Bacterial growth inhibition varied depending on the species, with reductions ranging from 70% to 92% for aerobic bacteria and over 90% for anaerobic strains. In conclusion, the AgCu nanolayer displayed high bactericidal and antiviral activity in contact and aerosol conditions. Therefore, it holds the potential for incorporation into personal protective equipment to effectively reduce and prevent the transmission of aerosol-borne pathogenic bacteria and respiratory viruses. [ABSTRACT FROM AUTHOR]

Zeolite has a great capacity of adsorption and ion exchange. Silver ions are impregnated into the zeolite matrix by ion exchange, which results in the formation of an antimicrobial complex. By using a factorial design, this study explores the influence of pH, temperature, and silver nitrate concentration on the characteristics of ZeAg complexes. The ZeAg8 complex, produced with the factors of [AgNO3] of 4000 mg/L, pH 5 and T 45 °C showed promising results, showing antimicrobial activity, and maintained an original crystalline structure of the zeolite after the experimental conditions. Experimental design analysis showed that lower pH and temperature favored larger particle diameter and induce disruption of the crystalline structure of the zeolite. Silver ions impregnation into zeolite under specific conditions create a potential antimicrobial complex for wound dressings, promoting tissue regeneration and healing while preventing potential complications associated with silver treatment. [ABSTRACT FROM AUTHOR]

Herein we present the results of optimization of silver nanoparticles biosynthesis using a nonpathogenic soil bacterium Azospirillum brasilense. The conditions and parameters for synthesis of biogenic nanoparticles using A. brasilense vegetative cells, culture liquid, and homogeneous polyphenol oxidase preparations were analyzed. We have revealed the ranging effect of the incubation time, the concentration of silver ions, pH of the reaction mixture, and the concentration of metabolites, towards the production of colloidal silver nanoparticles with specified geometric parameters, high colloidal stability and relatively good monodispersity. The size, shape, and relative yield of electron-dense nanostructures were determined by transmission electron microscopy and dynamic light scattering; extinction spectra were recorded by UV-vis spectrophotometry. [ABSTRACT FROM AUTHOR]

A quantitative study of the biodegradability of polymer soil conditioners is necessary for a reasonable prediction of their stability and functioning in soils. For this purpose, a new methodological approach based on PASCO (USA) equipment was proposed. This approach allows recording continuous kinetic curves of CO2 emission in laboratory experiments based on incubation of composite gel-forming soil conditioners. Several characteristic types of respiration curves have been identified, and new physically based models have been proposed for their description with subsequent calculation of the half-lives of composite hydrogels. For the traditionally considered non-biodegradable acrylic superabsorbents of soil water, the possibility of rapid biodegradation was shown for the first time in the case of the addition of a biologically active compost extract into their liquid phase. With this treatment, which brings laboratory experiments closer to real soil conditions, the half-lives of both the well-known European Aquasorb and Zeba superabsorbents and the Russian Aquapastus hydrogel decreased by an order of magnitude from the initial values of 2–6 years to 0.1–0.3 years. In practice, this can negatively affect the profitability of using such materials for soil conditioning due to their rapid destruction and loss of functionality. The addition of silver ions into innovative Aquapastus composite superabsorbents at a dose of 0.1% or 10 ppm in swollen gel structures effectively reduces their biodegradability, prolonging the half-life to 10 years or more, which is twice the German standard DüMV 05.12.12 of the stability of polymer ameliorants. [ABSTRACT FROM AUTHOR]

In silico studies have been carried out at PBE0‐D3/def2‐TZVP level of theory to disclose the nature of bonding in β‐D‐glucopyranose – silver ion (1:1) complex ([Ag(C6H12O6)]+). Moreover, the interaction of molecular hydrogen with the [Ag(C6H12O6)]+ complex is studied. In doing so, it is found that the metal site can interact with up to three hydrogen molecules with a binding energy of 5.3 kcal/mol per H2. Calculated ∆G298 K values disclose that the interaction of the first H2 with the [Ag(C6H12O6)]+ complex is exergonic, whereas a slightly endergonic nature of interaction is noted for the two and three H2 cases. Electron density and electron density‐based reactivity descriptors help in resolving the nature of interaction between metal ions and C6H12O6 as well as between the metal center and molecular hydrogens. An energy decomposition analysis reveals the orbital interaction as the major contributing factor to the total interaction energy for the one H2 case. Ab initio molecular dynamics study at different temperatures reveals kinetic stability of the hydrogen‐bound silver complex up to 1 ps. Conceptual density functional theory (CDFT) based reactivity descriptors, hardness and electrophilicity, help in assessing the stability trend of the hydrogen‐bound complexes during the simulation. [ABSTRACT FROM AUTHOR]

The paper presents the results of the synthesis, a detailed kinetics study, and an investigation of the biological activity of silver nanoparticles (AgNPs) in aqueous solutions of N-reacetylated oligochitosan hydrochloride. UV–visible spectrophotometry and dynamic light scattering were employed to control silver ion reduction. The process was observed to follow a pseudo-first-order law. Transmission and scanning electron microscopy demonstrated that AgNPs ranging in size from 10 to 25 nm formed aggregates measuring 60 to 90 nm, with the aggregate surface coated by a 2–4 nm chitosan shell. X-ray microanalysis and powder X-ray diffractometry were used to study the phase composition, identifying two crystalline phases, nanocrystalline silver and AgCl, present in the dispersions. The antibacterial effect was assessed using the serial dilution method for dispersions with varying degrees of Ag+ conversion. Nanodispersions exhibited significant activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus. Interestingly, the activity did not appear to be heavily influenced by the presence of the AgCl phase or the concentration of Ag+ ions. These synthesized dispersions hold promise for the development of materials tailored for biomedical applications. [ABSTRACT FROM AUTHOR]

A new method based on high performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) has been developed for the speciation analysis of silver nanoparticles (AgNPs) and dissolved silver forms (Ag(I)) in surface water and algal cells. Different compositions of the mobile phase, including surfactants preventing agglomeration/aggregation of AgNPs, pH buffers and complexing agents for silver ions, were carefully investigated to ensure complete elution and stability of silver species during chromatographic analysis. Under the optimal separation conditions (mobile phase: 10 mM sodium dodecyl sulfate, 2 mM citrate buffer, and 2 mM tiopronin), detection limits of 2.0 ng L−1 for Ag(I), 3.1 ng L−1 for 10 nm AgNPs, and 2.2 ng L−1 for 30 nm AgNPs were achieved. A linear relationship was found between the retention time of AgNPs and logarithm of particle diameter up to 40 nm, which can be used for the particle size determination in real samples. The HPLC-ICP-MS method has been successfully applied to study interactions of Ag(I) and citrate-stabilized AgNPs of different nominal diameters (10 nm and 30 nm) with green microalgae Acutodesmus obliquus in river water. The cell-associated fractions of silver were quite similar for all studied forms (silver biosorption was in the range of 77.2–82.7%). As a result of interaction with the biomass, biosynthesis of small nanoparticles (with a size of 6 nm) from Ag(I) ions and partial dissolution of 10 and 30 nm AgNPs were observed. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)–silver (Ag) nanocomposites are an up-and-coming antibacterial agent against bacteria. The antibacterial activity of GO–Ag nanocomposites depends on the concentration, particle size, and distribution of Ag nanoparticles on the GO sheets. Here, we explore the combined effect of the concentration and distribution of Ag nanoparticles on the GO sheets against the bacteria. For this purpose, three samples were prepared in such a way that the Ag nanoparticles were uniformly distributed on the GO sheets for the lowest concentration sample, but the medium concentration sample had moderate agglomeration of Ag nanoparticles, and the highest concentration sample had highly agglomerated Ag nanoparticles on the GO sheets. The particle size of Ag nanoparticles has also increased with increasing concentration of Ag. The modified Hummers method has been used to synthesize GO, and GO–Ag nanocomposites have been prepared by reducing AgNO 3 on GO sheets at room temperature with NaBH 4 as a reducing agent. Three different volumes of AgNO 3 are used to vary the concentration of Ag. All the samples were tested using field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), High-Resolution Transmission Electron Microscope (HRTEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analyzer (TGA). The results confirm the formation of GO–Ag nanocomposites with spherical-shaped Ag nanoparticles attached to the GO sheets. Antibacterial activities for all the GO–Ag nanocomposites were tested against the Gram-positive bacteria Bacillus subtilis using the disk diffusion method. All the nanocomposites show antibacterial activities. Our investigation established that the combined effect of concentration and distribution of Ag nanoparticles on GO sheets decides the antibacterial efficiency of the GO–Ag nanocomposites. [ABSTRACT FROM AUTHOR]

This study used the Tamarix gallica aqueous extract to simultaneously reduce silver ions and graphene oxide (GO), forming the AgNPs/GO nanocomposite in a single step. The agar diffusion method determines the material's antibacterial activity and tests its effectiveness against Gram-negative Escherichia coli ATCC 25922 and Gram-positive Staphylococcus aureus ATCC 29213. The properties of products were analyzed using various methods such as UV–Vis, SEM, XRD, STEM, and FT-IR to determine their morphology, structure, and chemical composition. XRD, SEM, and STEM analysis revealed that silver nanoparticles (AgNPs) were deposited on reduced graphene oxide (rGO). The AgNPs were semi-spherical in shape and had a face-centered cubic crystal structure with a size ranging from 5 to 40 nm. AgNPs/GO is antibacterial and effective against Escherichia coli and Staphylococcus aureus. However, Ag/rGO was more effective against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Present is a low-cost and environmentally beneficial approach for producing silver nanoparticles from discarded pineapple leaves utilising microwave-assisted extraction. AgNPs are produced environmentally friendly using a straightforward reduction technique and silver nitrate. The ideal conditions for green synthesis are determined by taking into account a number of factors, such as the silver nitrate concentration (5–25 mM), the incubation period (2–24 h), and the sample volume (2–8 mL). The reduction of silver metal ions into silver nanoparticles is indicated by the appearance of an absorption band in the UV-Vis spectro-photometer between 400 and 500 nm. Longer run times, higher silver nitrate solution concentrations, and larger sample volumes are all observed to improve absorption intensity. The green synthesised silver nanoparticles range in size from 40 to 150 nm and exhibit hexagonal spherical shapes, according to FE-SEM studies. Furthermore, the presence of green synthesised AgNPs is confirmed by FTIR and XRD studies. In comparison to non-microwave-assisted treatment, silver nanoparticles treated with a microwave show increased antibacterial activity against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Silver nanoparticles must be present at a minimum of 60 g/mL to suppress bacterial growth. Overall, this study provides an avenue with substantial potential for the environmentally friendly and economically advantageous green synthesis of silver nanoparticles employing the microwave-assisted technique [ABSTRACT FROM AUTHOR]

Titanium is a component of many implants and orthopedic instruments, such as screws and rods; however, this and other materials may serve as a nidus for bacterial biofilm attachment. Chitosan is a biopolymer with advantages as a surface modifier, and silver ions have broad-spectrum antimicrobial properties. For this study, chitosan is bound to silver through a novel, patented process. The purpose of this research is to characterize silane-linked chitosan-silver coatings for titanium, including comparing antimicrobial efficacy. In this study, silane-linked chitosan-silver titanium coupons reduced Staphylococcus aureus (S. aureus) viability by 98% (planktonic) and 99.5% (biofilm) while supporting viability of Saos-2 osteoblast cells at levels of 75% compared with control uncoated titanium. Due to the observation of retaining osteoblast viability while reducing bacterial viability, silane-linked chitosan-silver coatings could be useful for titanium implants to reduce post-operative infection as well as support the healing process. [ABSTRACT FROM AUTHOR]

Silver ions (Ag+) exist widely in various areas of human life, and the food contamination caused by them poses a serious threat to human health. Among the numerous methods used for the detection of Ag+, fluorescence and colorimetric analysis have attracted much attention due to their inherent advantages, such as high sensitivity, simple operation, short time, low cost and visualized detection. In this work, Pd/Pt nanoflowers (NFs) specifically responsive to Ag+ were synthesized in a simple way to oxidize o-phenylenediamine (OPD) into 2,3-diaminophenazine (DAP). The interaction of Ag+ with the surface of Pd/Pt NFs inhibits the catalytic activity of Pd/Pt NFs towards the substrate OPD. A novel dual-channel nanosensor was constructed for the detection of Ag+, using the fluorescence intensity and UV-vis absorption intensity of DAP as output signals. This dual-mode analysis combines their respective advantages to significantly improve the sensitivity and accuracy of Ag+ detection. The results showed that the limit of detection was 5.8 nM for the fluorescence channel and 46.9 nM for the colorimetric channel, respectively. Moreover, the developed platform has been successfully used for the detection of Ag+ in real samples with satisfactory recoveries, which is promising for the application in the point-of-care testing of Ag+ in the field of food safety. [ABSTRACT FROM AUTHOR]

The aim of this work was to propose a simple method for synthesizing differently shaped AgNPs and to find a suitable stabilizing/capping agent to ensure the non-toxicity of AgNPs. Using a chemical method, by simply changing the volume of reducing agents, we successfully prepared colloids of differently shaped AgNPs (spherical (~10 nm), triangular (~40 nm), rodlike (~30 nm), and a mixture of these shapes). The nanoparticle sizes and shapes affect the solution color. UV-VIS spectroscopy was used to evaluate the colloidal solutions, and transmission electron microscopy was used to analyze the shape and size of the nanoparticles. To create non-toxic and stable AgNPs, it is necessary to modify the surface properties of the nanoparticles; one possibility is to create a biocompatible layer on the nanoparticle surface. We successfully applied a combination of trisodium citrate and polyvinylpyrrolidone, thereby preventing the release of silver ions, which are responsible for the toxic effects of AgNPs. The synthesized nanoparticles show very low, mostly negligible antibiofilm activity against the green algae Chlorella kessleri. AgNPs were used to prepare polymer-AgNP composite thin layers and fibers. It was proved that AgNPs can influence polymer matrix properties. [ABSTRACT FROM AUTHOR]

The formation of a silver-containing porous layer on the surface of KEF-4,5 single-crystal silicon by ion-beam doping was studied. The dose and energy of helium and silver ions in the experiment were determined by computer simulation of ion doping of KEF-4,5 silicon with high-energy helium and silver ions using the TRIM/SRIM software. The porous surface relief, density of quasi-pores on the ion-implanted silicon surface, and elemental composition of the obtained porous silver-containing composite layers were investigated taking into account the effect of the intermediate heat treatment. The ion-beam-assisted formation of a silver-containing coating ensures the creation of a developed surface relief on the nanoscale with high reproducibility and controllability inherent in the ion doping method. Using the experimental data obtained, the porous surface relief and density of quasi-pores on the ion-implanted silicon surface were examined as functions of the helium ion energy and dose. Ion doping conditions were established. The silver ion implantation parameters were determined by studying the elemental composition of the obtained quasi-porous silver-containing composite layer. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are known to affect the physiology and morphology of plants in various ways, but the exact mechanism by which they interact with plant cells remains to be elucidated. An unresolved question of silver nanotoxicology is whether the interaction is triggered by the physical features of the particles, or by silver ions leached from their surface. In this study, we germinated and grew Arabidopsis thaliana seedlings in synthetic medium supplemented with sub-morbid concentrations (4 μg/mL) of AgNPs and silver nitrate (AgNO3). This treatment led to in planta accumulation of 106 μg/g and 97 μg/g of silver in the AgNO3- and AgNP-exposed seedlings, respectively. Despite the statistically indistinguishable silver accumulation, RNA sequencing data demonstrated distinct changes in the transcriptome of the AgNP-exposed, but not in the AgNO3-exposed plants. AgNP exposure induced changes in the expression of genes involved in immune response, cell wall organization, photosynthesis and cellular defense against reactive oxygen species. AgNO3 exposure, on the other hand, caused the differential expression of only two genes, neither of which belonged to any AgNP-enriched gene ontology categories. Moreover, AgNP exposure led to a 39% reduction (p

Silver ions are regarded as one of the most hazardous metal contaminants, endangering both the ecological environment and human health. Traditional silver ions detection technologies are hampered by their high cost, time-consuming nature, and labor-intensive operation. DNA aptamers play an essential part in the field of biosensors due to their ease of synthesis, ease of modification, and low cost. This paper focuses on reviewing the research progress of DNA aptamer-based biosensors in silver ions detection. According to the types of signal transduction, they are classified into four forms of signal transduction: fluorescent biosensors, colorimetric biosensors, electrochemical biosensors, and surface-enhanced Raman spectroscopy biosensors. In addition, this paper gives a perspective on the application prospects outlook and development directions of DNA aptamer-based biosensors, in order to provide theoretical ideas for the future development of more sensitive DNA aptamer biosensors for rapid detection of silver ions.

Abstract Background Hydroxyapatites (HAp) are widely used as medical preparations for e.g., bone replacement or teeth implants. Incorporation of various substrates into HAp structures could enhance its biological properties, like biocompatibility or antimicrobial effects. Silver ions possess high antibacterial and antifungal activity and its application as HAp dopant might increase its clinical value. Results New silicate-substituted hydroxyapatites (HAp) doped with silver ions were synthesized via hydrothermal methods. The crystal structure of HAp was investigated by using the X-ray powder diffraction. Antifungal activity of silver ion-doped HAp (with 0.7 mol%, 1 mol% and 2 mol% of dopants) was tested against the yeast-like reference and clinical strains of Candida albicans, C. glabrata, C. tropicalis, Rhodotorula rubra, R. mucilaginosa, Cryptococcus neoformans and C. gattii. Spectrophotometric method was used to evaluate antifungal effect of HAp in SD medium. It was shown that already the lowest dopant (0.7 mol% of Ag+ ions) significantly reduced fungal growth at the concentration of 100 µg/mL. Increase in the dopant content and the concentration of HAp did not cause further growth inhibition. Moreover, there were some differences at the tolerance level to Ag+ ion-doped HAp among tested strains, suggesting strain-specific activity. Conclusions Preformed studies confirm antimicrobial potential of hydroxyapatite doped with silver. New Ag+ ion-HAp material could be, after further studies, considered as medical agent with antifungal properties which lower the risk of a surgical-related infections.

Abstract Silver recovery from sustainable sources such as seawater and e‐waste is critical for the conservation of land‐based resources and the reduction of the environmental impacts of e‐waste disposal. However, the abundance of competing metal ions in seawater and in e‐waste makes the recovery extremely challenging. Thus, to effectively capture silver ions under these conditions, the designing of materials with high selectivity, sufficient binding sites, and low affinity to competing metal ions is vital. Herein, we report the design and synthesis of a 3D‐like Schiff‐bridging crown‐based material named AC5, for the selective recovery of Ag+ ions. Through this design, a significant enhancement in the silver ion recovery was achieved with an excellent removal efficiency of up to 99.9%, and a tremendous increase in selectivity of 400 000 – 900 000% when compared to the metal ions (Li+, Na+, K+, Mg2+, and Ca2+) found in seawater, and the heavy metal ions (Cu2+, Cd2+, Ni2+, and Pb2+) found in electronic wastes. Density functional theory and molceular dynamics simulations revealed that the structural geometry of AC5 favors high charge transfer, lowered global hardness, and enhanced ion‐dipole attractions toward Ag+ ions, making the material an excellent candidate for the efficient recovery of silver from desalination brine and spent silver resources.

The aims of this study were: To evaluate the surface hardness of simulated dentin caries lesions treated with either silver nanoclusters (AgNCls) synthesized in polymethacrylic acid (PMAA) or 38% silver diammine fluoride (SDF), as well as observe the penetration of the treatment solutions into the simulated caries lesions. Dentin blocks 4 mm thick obtained from caries-free third molars were sectioned and then simulated caries lesions on the occlusal dentin surfaces were created. Each specimen (n = 8) was divided into four sections: (A) treated with 20% AgNCls/PMAA; (B) treated with SDF 38% (FAgamin, Tedequim, Cordoba, Argentina); (C) sound tooth protected by nail-varnish during artificial caries generation (positive control); and (D) artificial caries lesion without surface treatment (negative control). AgNCls/PMAA or SDF were applied on the simulated lesions with a microbrush for 10 s, then excess removed. The surface hardness was measured by means of Vickers indentation test. To trace the depth of penetration, up to 400 μm, of silver ions, elemental composition of the samples was observed using EDX, coupled with SEM, and measured every 50 μm from the surface towards the pulp chamber. Laser Induced Breakdown Spectroscopy (LIBS) was also employed to trace silver ion penetration; the atomic silver line 328.06 nm was used with a 60 μm laser spot size to a depth of 240 μm. Student's-t test identified significant differences between treatment groups for each depth and the Bonferroni test was used for statistical analysis of all groups (p < 0.05). Mean surface hardness values obtained were 111.2 MPa, 72.3 MPa, 103.3 MPa and 50.5 MPa for groups A, B, C and D respectively. There was a significant difference between groups A and C compared with groups B and D, the group treated with AgNCls/PMAA achieved the highest surface hardness, similar or higher than the sound dentin control. A constant presence of silver was observed throughout the depth of the sample for group A, while group B showed a peak concentration of silver at the surface with a significant drop beyond 50 μm. The 20% AgNCls/PMAA solution applied to simulated dentin caries lesions achieved the recovery of surface hardness equivalent to sound dentin with the penetration of silver ions throughout the depth of the lesion. [ABSTRACT FROM AUTHOR]

Addressing the growing need for environmentally friendly fungicides in agriculture, this study explored the potential of biopolymer microparticles loaded with metal ions as a novel approach to combat fungal pathogens. Novel alginate microspheres and chitosan/alginate microcapsules loaded with zinc or with zinc and silver ions were prepared and characterized (microparticle size, morphology, topography, encapsulation efficiency, loading capacity, and swelling behavior). Investigation of molecular interactions in microparticles using FTIR-ATR spectroscopy exhibited complex interactions between all constituents. Fitting to the simple Korsmeyer–Peppas empirical model revealed the rate-controlling mechanism of metal ions release from microparticles is Fickian diffusion. Lower values of the release constant k imply a slower release rate of Zn2+ or Ag+ ions from microcapsules compared to that of microspheres. The antimicrobial potential of the new formulations against the fungus Botrytis cinerea was evaluated. When subjected to tests against the fungus, microspheres exhibited superior antifungal activity especially those loaded with both zinc and silver ions, reducing fungal growth up to 98.9% and altering the hyphal structures. Due to the slower release of metal ions, the microcapsule formulations seem suitable for plant protection throughout the growing season. The results showed the potential of these novel microparticles as powerful fungicides in agriculture. [ABSTRACT FROM AUTHOR]

Silver-containing wound dressings have shown attractive advantages in the treatment of wound infection due to their excellent antibacterial activity. However, the introduction of silver ions or AgNPs directly into the wound can cause deposition in the body as particles. Here, with the aim of designing low-silver wound dressings, a bimetallic-MOF antibacterial material called AgCu@MOF was developed using 3, 5-pyridine dicarboxylic acid as the ligand and Ag+ and Cu2+ as metal ion sites. PCbM (PVA/chitosan/AgCu@MOF) hydrogel was successfully constructed in PVA/chitosan wound dressing loaded with AgCu@MOF. The active sites on the surface of AgCu@MOF increased the lipophilicity to bacteria and caused the bacterial membrane to undergo lipid peroxidation, which resulted in the strong bactericidal properties of AgCu@MOF, and the antimicrobial activity of the dressing PCbM was as high as 99.9%. The chelation of silver ions in AgCu@MOF with chitosan occupied the surface functional groups of chitosan and reduced the crosslinking density of chitosan. PCbM changes the hydrogel crosslinking network, thus improving the water retention and water permeability of PCbM hydrogel so that the hydrogel has the function of binding wet tissue. As a wound adhesive, PCbM hydrogel reduces the amount of wound bleeding and has good biocompatibility. PCbM hydrogel-treated mice achieved 96% wound recovery on day 14. The strong antibacterial, tissue adhesion, and hemostatic ability of PCbM make it a potential wound dressing. [ABSTRACT FROM AUTHOR]

Modified polymer design has attracted significant attention for enzyme immobilization, offering promising applications. In this study, amine-terminated polymers were synthesized by incorporating functional groups into polyacrylonitrile using hexamethylenediamine. This work highlights the successful enzyme immobilization strategy using modified polymers, offering improved stability and expanded operational conditions for potential biotechnological applications. The resulting amino groups were utilized to capture silver ions, which were subsequently converted to silver nanoparticles (AgNPs). The obtained materials, AgNPs@TA-HMDA (acrylic textiles coated silver nanoparticles AgNPs) and Ag(I)@TA-HMDA (acrylic textiles coated with Ag ion) were employed as supports for β-glucosidase enzyme immobilization. The highest immobilization yields (IY%) were achieved with AgNPs@TA-HMDA at 92%, followed by Ag(I)@TA-HMDA at 79.8%, resulting in activity yields (AY%) of 81% and 73%, respectively. Characterization techniques such as FTIR, FE-SEM, EDX, TG/DTG, DSC, and zeta potential were employed to investigate the structural composition, surface morphologies, elemental composition, thermal properties, and surface charge of the support materials. After 15 reuses, the preservation percentages decreased to 76% for AgNPs@TA-HMDA/β-Glu and 65% for Ag(I)@TA-HMDA/β-Glu. Storage stability revealed that the decrease in activity for the immobilized enzymes was smaller than the free enzyme. The optimal pH for the immobilized enzymes was broader (pH 5.5 to 6.5) compared to the free enzyme (pH 5.0), and the optimal temperature for the immobilized enzymes was 60 °C, slightly higher than the free enzyme's optimal temperature of 50 °C. The kinetic analysis showed a slight increase in Michaelis constant (Km) values for the immobilized enzymes and a decrease in maximum velocity (Vmax), turnover number (Kcat), and specificity constant (Kcat/Km) values compared to the free enzyme. Through extensive characterization, we gained valuable insights into the structural composition and properties of the modified polymer supports. This research significantly contributes to the development of efficient biotechnological processes by advancing the field of enzyme immobilization and offering valuable knowledge for its potential applications. [ABSTRACT FROM AUTHOR]

Here, we synthesized a cytidine-based surfactant and anchored it onto the surface of liquid crystal (LC) droplets to enable the specific detection of silver ions. The synthesized surfactant could induce LC droplets into a radial configuration, and the introduction of silver ions changed the configuration of LC droplets in an intermediate (including escaped-radial and axial) configuration within 2 min. The LC droplet-based sensor developed here can specifically respond to the silver ions as low as 0.6 μM, making it suitable for the detection of Ag+ in environmental and food samples. [Display omitted] Liquid crystal (LC) droplets exhibit unique and sensitive response behaviors to surface absorptions, making them promising candidates for sensing aplications. Here, we have developed a label-free, portable, and cost-effective sensor for the specific and rapid detection of silver ions (Ag+) in drinking-water samples. To achieve this, we have modified cytidine into a surfactant (denoted as C10–M–C) and anchored it onto the surface of LC droplets. The specific binding ability between cytidine and Ag+ enables LC droplets anchored with C10–M–C to respond rapidly and specifically to Ag+ ions. Furthermore, the sensitivity of the response meets requirements for the harmless concentration of Ag+ in drinking-water. The sensor we developed is label-free, portable, and cost-effectively. We believe that the sensor reported here can be applied to the detection of Ag+ in drinking-water and environmental samples. [ABSTRACT FROM AUTHOR]

Poly[n]catenanes have exceptional mechanical bonding properties that give them tremendous potential for use in the development of molecular machines and soft materials. Synthesizing these compounds has, however, proven to be a formidable challenge. Herein, we describe a concise method for the construction of twisted polycatenanes. Our approach involves using preorganized double helicates as templates, linked crosswise in a linear fashion by either silver ions or triple bonds. By using this approach, we successfully synthesized twisted polycatenanes with both coordination and covalent bonding employing Ag(I) ions and ethynylene units, respectively, as the linkages and leveraging the same Ag(I)‐templated double helicate in both cases. Synthesis with Ag(I) ions formed a single‐crystalline one‐dimensional (1D) coordination poly[n]catenane, and synthesis using ethynylene units generated 1D fibers which self‐assembled with solvents to form a gel. Our results confirm the potential of multi‐stranded metallohelicates for creating sophisticated mechanically interlocked molecules and polymers, which could pave the way for exploration in the realms of molecular nanotopology and materials design. [ABSTRACT FROM AUTHOR]

Two new Ag(I) complexes with 1,1,1,5,5,6,6,6-octafluorohexane-2,4-dionate ion (Ofhac) and π‑donor neutral ligands, vinyltriethylsilane (VTES) or cycloocta-1,5-diene (COD), were synthesized with the goal to expand the library of silver precursors for chemical vapor deposition. The products were characterized by elemental analysis and IR and NMR spectroscopy. The complex [Ag(VTES)(Ofhac)] (I) was liquid under standard conditions; the temperature of its crystallization was below –20°C. Treatment of I with benzene gave rise to crystals of [Ag4(C6H6)2(Ofhac)4]∞ (II), which was confirmed by NMR and X-ray diffraction (CCDC no. 2232810). The structure of [Ag(COD)(Ofhac)]2 (III) was established by X-ray diffraction (CCDC no. 2232809). The binuclear molecules are formed due to the μ2-κ1(O):κ1(O') function of the Ofhac ligands (Ag–O, 2.458(2)–2.461(2) Å), while COD is κ2-η2:η2-coordinated (Ag–C, 2.420(17)–2.684(11) Å). The thermal properties of I and III in comparison with analogues containing 1,1,1,5,5,5-hexafluoropentane-2,4-dionate ion (Hfac) were studied by thermogravimetry. [ABSTRACT FROM AUTHOR]

The integration of hydroxyapatite (HA) with broad-spectrum bactericidal nano-silver within biopolymer-based bone scaffolds not only promotes new bone growth, but also effectively prevents bacterial infections. However, there are problems such as a poor interface compatibility and easy agglomeration. In this project, zeolitic imidazolate frameworks (ZIF-8) were grown in situ on nano-HA to construct a core–shell structure, and silver was loaded into the ZIF-8 shell through ion exchange. Finally, the core–shell structure (HA@Ag) was composited with polylactic acid (PLLA) to prepare bone scaffolds. In this case, the metal zinc ions of ZIF-8 could form ionic bonds with the phosphate groups of HA by replacing calcium ions, and the imidazole ligands of ZIF-8 could form hydrogen bonds with the carboxyl groups of the PLLA, thus enhancing the interface compatibility between the biopolymers and ceramics. Additionally, the frame structure of MOFs enabled controlling the release of silver ions to achieve a long-term antibacterial performance. The test results showed that the HA@Ag nanoparticles endowed the scaffold with good antibacterial and osteogenic activity. Significantly, the HA@Ag naoaprticle exhibited a good interfacial compatibility with the PLLA matrix and could be relatively evenly dispersed within the matrix. Moreover, the HA@ZIF-8 also effectively enhanced the mechanical strength and degradation rate of the PLLA scaffold. [ABSTRACT FROM AUTHOR]

Biosynthesis of carbon-based materials via pyrolysis and hydrothermal methods have emerged as a cost-effective strategy towards fabrication of biosensors for electrochemical sensing applications. The porosity, surface area and active sites on bio-derived carbon materials greatly influence the electrochemical sensing performance of modified electrodes. Herein, we report synthesis of carbon quantum dots by pyrolysis of Halimeda Opuntia green algae and doping with silver nanoparticles (AgNPs@CQDs) for the fabrication of electrochemical sensing platform of D-glucose and paracetamol. The structural and morphological features of AgNPs@CQDs were analyzed using SEM, XRD, FTIR and UV–Vis spectroscopy. Simultaneous determination of D-glucose and paracetamol in 1M KOH solution was performed using GCE-modified AgNPs@CQDs. The cyclic voltammetry confirms excellent electrochemical performance of GCE-modified AgNPs@CQDs electrodes. AgNPs@CQDs composites electrodes show improved sensing response in the pH range 4–7 with optimum values at pH = 7 for both D-glucose and paracetamol. The GCE modified by AgNPs@CQDs electrodes exhibit highly linear response for both D-glucose and paracetamol. Limit of detection was found to be 0.32 µM and 0.29 µM for D-glucose and paracetamol, respectively. The GCE-modified AgNPs@CQDs composites electrodes show fast response time of 33 s and 21 s, respectively, for D-glucose and paracetamol at a concentration of 10 µM. Furthermore, the AgNPs@CQDs composites electrodes show highly selective response towards D-glucose and paracetamol against various other target analytes. Due to ease of bio synthesis, low-cost fabrication, excellent electrochemical performance towards detection of D-glucose and paracetamol, the AgNPs@CQDs could be a potential material to fabricate versatile sensors towards simultaneous determination of D-glucose and paracetamol. [ABSTRACT FROM AUTHOR]

Herein, we investigated the photoreduction of silver (Ag) ions on gold nanorods coated with mesoporous silica shell (AuNRs@mSiO2) induced by hot electrons generated in Au via localized surface plasmon resonance (LSPR) excitation. In addition, we investigated chemical interface damping (CID) using pyridine as the adsorbate in single Ag‐coated AuNRs@mSiO2. The Ag deposition caused a blue shift and linewidth broadening of the LSPR peak of the AuNRs@mSiO2. The subsequent chemisorption of pyridine on Ag‐coated AuNRs@mSiO2 resulted in a red shift and additional LSPR linewidth broadening. Finally, we demonstrated real‐time time‐dependent changes in LSPR peak wavelength and linewidth during the sequential processes of hot electron‐mediated Ag deposition and pyridine adsorption on a single AuNR@mSiO2 in a flow cell. Therefore, we provided a deep understanding of hot electron‐triggered Ag coating and CID induced by pyridine adsorption in single AuNRs@mSiO2 coated with Ag. [ABSTRACT FROM AUTHOR]

In this work, a coordination polymer material ([Ag4(BPB) 4SiW12O40]) (Complex 1) based on silicotungstic heteropoly acid (H4SiWi11O40) and silver ion metal center was synthesized by hydrothermal synthesis method. The single crystal X-ray diffraction analysis showed that there were three kinds of silver ions Agl, Ag2 and Ag3 with coordination numbers of 2, 3, and 4, respectively. The Ag metal center is coordinated with N of the organic ligands and O of the polyacids. Ag1 connects organic ligands to form left-and right-handed helical chains, and connects polyacid molecules to form trapezoidal chains; Ag2 connects organic ligands and polyacid molecules to form a two-dimensional 4,4-sql lattice layer, sharing polyacid molecules with trapezoidal chains; Ag3 connects organic ligands to form one-dimensional chain through the two-dimensional layer, ultimately forming the overall three-dimensional structure. The electrochemical performance of the material was studied using a composite modified glassy carbon lectrode (GCE) as the working electrode, and electrochemical analysis showed that the material can used as an electrocatalyst for the reduction of NaNO3. [ABSTRACT FROM AUTHOR]

The L-cysteine-functionalized silica (SG-Cys−Na+) matrix was effectively loaded with silver (I) ions using the batch sorption technique. Optimal Ag(I) loading into SG-Cys−Na+ reached 98% at pHi = 6, 80 rpm, 1 mg L−1, and a temperature of 55 °C. The Langmuir isotherm was found to be suitable for Ag(I) binding onto SG-Cys−Na+ active sites, forming a homogeneous monolayer (R2 = 0.999), as confirmed by FTIR spectroscopy. XRD analysis indicated matrix stability and the absence of Ag2O and Ag(0) phases, observed from diffraction peaks. The pseudo-second-order model (R2 > 0.999) suggested chemisorption-controlled adsorption, involving chemical bonding between silver ions and SG-Cys−Na+ surface. Thermodynamic parameters were calculated, indicating higher initial concentrations leading to increased equilibrium constants, negative ΔG values, positive ΔS values, and negative ΔH. This study aimed to explore silver ion saturation on silica surfaces and the underlying association mechanisms. The capability to capture and load silver (I) ions onto functionalized silica gel materials holds promise for environmental and water purification applications. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) have been synthesized using Rhoeo discolor leaf extract as a reducing and stabilizing agent. AgNPs were synthesized by adding silver nitrate to the extract of Rhoeo discolor and incubating it in a boiling water bath. The change in color of the mixture from clear to yellow indicated AgNPs formation. The synthesized AgNPs were spherical and showed an absorption peak at around 410-420 nm. The size of particles was distributed from 3 to 18 nm with an average size of 8 ± 2 nm, and the polydispersity index was 0.185. The stability test showed that synthesized AgNPs were stable for three months of storage at ambient temperature. The extract of Rhoeo discolor were responsible for reducing silver ion and stabilizing the synthesized AgNPs. [ABSTRACT FROM AUTHOR]

Multi-drug resistant bacteria sometimes known as "superbugs" developed through overuse and misuse of antibiotics are determined to be sensitive to small concentrations of silver nanoparticles. Various methods and sources are under investigation for the safe and efficient synthesis of silver nanoparticles having effective antibacterial activity even at low concentrations. We used a medicinal plant named Salvia moorcroftiana to extract phytochemicals with antibacterial, antioxidant, and reducing properties. Three types of solvents; from polar to nonpolar, i.e., water, dimethyl sulfoxide (DMSO), and hexane, were used to extract the plant as a whole and as well as in fractions. The biosynthesized silver nanoparticles in all extracts (except hexane-based extract) were spherical, smaller than 20 nm, polydispersed (PDI ranging between 0.2 and 0.5), and stable with repulsive force of action (average zeta value = -18.55±1.17). The tested bacterial strains i.e., Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis were found to be sensitive to even small concentrations of Ag-NPs, especially P. aeruginosa. The antibacterial effect of these Ag-NPs was associated with their ability to generate reactive oxygen species. DMSO (in fraction) could efficiently extract antibacterial phytochemicals and showed activity against MDR bacteria (inhibition zone = 11–12 mm). Thus, the antibacterial activity of fractionated DMSO extract was comparable to that of Ag-NPs because it contained phytochemicals having solid antibacterial potential. Furthermore, Ag-NPs synthesized from this extract owned superior antibacterial activity. However, whole aqueous extract-based Ag-NPs MIC was least (7–32 μg/mL) as compared to others. [ABSTRACT FROM AUTHOR]

We developed an improved, robust synthesis of a series of pillar[6]arenes with a varying number (0–3) of quinone moieties in the ring. This easy-to-control variation yielded a gradually less electron-rich cavity in going from zero to three quinone units, as shown from the strength of host–guest interactions with silver ions. Such macrocycle-Ag2 complexes themselves were shown to display an unprecedented, sharp distinction between terminal alkynes, which strongly bound to such complexes, and internal alkynes, internal alkenes and terminal alkenes, which do hardly bind. [ABSTRACT FROM AUTHOR]

Alkylresorcinols (∑ARs) is the generic term for a highly varied class of lipids found mainly in cereals. These bioactive compounds consist mainly of 5‐alkylresorcinols (ARs), which differ in length, unsaturation, and substituents on the alkyl side chain on C‐5. In addition, 2‐methyl‐5‐alkylresorcinols (mARs) are scarcely studied minor compounds that are supposed to exist with the same structural diversity. In the first step, ∑ARs were enriched by solid‐phase extraction from wheat grain and quinoa seed extracts. The subsequent application of silver ion chromatography (SIC), silica gel, coated with 20% AgNO3, then deactivated with 1% water) enabled an unprecedented full separation of saturated mARs from conventional ARs. Specifically, saturated mARs were eluted with n‐hexane/ethyl acetate (92:8, v/v), and conventional ARs with n‐hexane/ethyl acetate (80:20, v/v). The unpreceded separation indicated that the SIC method could be useful not only for separations according to the degree of unsaturation, but also in the case of steric hindrance by additional (alkyl) substituents. Continued fractionation enabled the collection of unsaturated ARs in wheat and quinoa extracts. In this way, 35 ∑ARs (including five mARs) were detected by gas chromatography/mass spectrometry analysis in wheat and 45 ∑ARs (including 21 mARs) in quinoa. These included several low abundant and partly unknown ∑ARs such as 1,3‐dihydroxy‐5‐tricosadienylbenzene. [ABSTRACT FROM AUTHOR]

Furan fatty acids (FuFAs) are valuable minor fatty acids, which are known for their excellent radical scavenging properties. Typically, the furan moiety is embedded in an otherwise saturated carboxyalkyl chain. Occasionally, these classic FuFAs are accompanied by low amounts of unsaturated furan fatty acids (uFuFAs), which additionally feature one double bond in conjugation with the furan moiety. A recent study produced evidence for the occurrence of two pairs of E-/Z-uFuFA isomers structurally related to saturated uFuFAs. Here, we present a strategy that allowed such trace compounds to be enriched to a level suited for structure determination by NMR. Given the low amounts and the varied abundance ratio of the four uFuFA isomers, the isolation of individual compounds was not pursued. Instead, the entire isomer mixture was enriched to an amount and purity suitable for structure investigation with contemporary NMR methods. Specifically, lipid extracted from 150 g latex, the richest known source of FuFAs, was subsequently fractionated by countercurrent chromatography (CCC), silver ion, and silica gel column chromatography. Analysis of the resulting mixture of four uFuFAs isomers (2.4 mg in an abundance ratio of 56:23:11:9) by different NMR techniques including PSYCHE verified that the structures of the two most abundant isomers were E-9-(3-methyl-5-pentylfuran-2-yl)non-8-enoic acid and E-9-(3-methyl-5-pent-1-enylfuran-2-yl)nonanoic acid. Additionally, we introduced a computer-based method to generate an averaged chromatogram from freely selectable GC/MS runs of CCC fractions without the necessity of pooling aliquots. This method was found to be suitable to simplify subsequent enrichment steps. [ABSTRACT FROM AUTHOR]

Electrochemical sensing is ubiquitous in a number of fields ranging from biosensing, to environmental monitoring through to food safety and battery or corrosion characterisation. Whereas conventional potentiostats are ideal to develop assays in laboratory settings, they are in general, not well-suited for field work due to their size and power requirements. To address this need, a number of portable battery-operated potentiostats have been proposed over the years. However, most open source solutions do not take full advantage of integrated circuit (IC) potentiostats, a rapidly evolving field. This is partly due to the constraining requirements inherent to the development of dedicated interfaces, such as apps, to address and control a set of common electrochemical sensing parameters. Here we propose the PocketEC, a universal app that has all the functionalities to interface with potentiostat ICs through a user defined property file. The versatility of PocketEC, developed with an assay developer mindset, was demonstrated by interfacing it, via Bluetooth, to the ADuCM355 evaluation board, the open-source DStat potentiostat and the Voyager board, a custom-built, small footprint potentiostat based around the LMP91000 chip. The Voyager board is presented here for the first time. Data obtained using a standard redox probe, Ferrocene Carboxylic Acid (FCA) and a silver ion assay using anodic stripping multi-step amperometry were in good agreement with analogous measurements using a bench top potentiostat. Combined with its Voyager board companion, the PocketEC app can be used directly for a number of wearable or portable electrochemical sensing applications. Importantly, the versatility of the app makes it a candidate of choice for the development of future portable potentiostats. Finally, the app is available to download on the Google Play store and the source codes and design files for the PocketEC app and the Voyager board are shared via Creative Commons license (CC BY-NC 3.0) to promote the development of novel portable or wearable applications based on electrochemical sensing. [ABSTRACT FROM AUTHOR]

The widespread prevalence of infectious bacteria is one of the greatest threats to public health, and consequently, there is an urgent need for efficient and broad-spectrum antibacterial materials that are antibiotic-free. In this study, 2-pyridinecarboxaldehyde (PCA) was grafted onto chitosan (CS) and the modified CS coordinated with silver ions to prepare PCA-CS-Ag complexes with antibacterial activity. To obtain complexes with a high silver content, the preparation process was optimized using single-factor experiments and response surface methodology. Under the optimal preparation conditions (an additional amount of silver nitrate (58 mg), a solution pH of 3.9, and a reaction temperature of 69 °C), the silver content of the PCA-CS-Ag complex reached 13.27 mg/g. The structure of the PCA-CS-Ag complex was subsequently verified using ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. Furthermore, three possible complexation modes of the PCA-CS-Ag complex were proposed using molecular mechanics calculations. The results of the antibacterial assay in vitro showed that the PCA-CS-Ag complex exhibited strong antibacterial activity against both Gram-positive and Gram-negative bacteria, exerting the synergistic antibacterial effect of modified chitosan and silver ions. Therefore, the PCA-CS-Ag complex is expected to be developed as an effective antibacterial material with promising applications in food films, packaging, medical dressings, and other fields. [ABSTRACT FROM AUTHOR]

Silver nanoparticles were obtained in MeCN/0.05 M Bu4NPF6 medium by сyclobis(paraquat-p‑phenylene)-mediated reduction of the silver ions generated by anodic oxidation of metallic silver during the electrolysis in an undivided cell. Due to multipoint donor–acceptor interaction, the сyclobis(paraquat-p‑phenylene) binds the resulting electron-donor silver nanoparticles to each other, which leads to their enlargement, aggregation, and adsorption. This property of the macrocycle allows calling the сyclobis(paraquat-p-phenylene) a molecular glue for silver nanoparticles. In the absence of stabilizers, aggregated polydisperse silver nanoparticles of indeterminate shape are formed, sized 20 to 500 nm. Electrosynthesis in the presence of polyvinylpyrrolidone as a stabilizer also leads to the formation of aggregated smaller (55 ± 26 nm) metal particles which have, in addition to the quasi-spherical shape, the shape of a flat triangle and hexagon. Silver nanoparticles stabilized by polyvinylpyrrolidone are partially bound on the surface of nanocellulose. In the presence of nanocellulose, larger silver nanoparticles with an average size of 97 ± 29 nm are formed, mainly shaped quasi-spherical; cubic, tetrahedral, and rod-shaped silver nanoparticles are also formed; no silver nanoparticles with a flat structure has been formed. The catalytic activity of the obtained particles in the reduction of p-nitrophenol by sodium borohydride is extremely low due to their large size, aggregation, and coating of the silver nanoparticles' surface with the stabilizer polyvinylpyrrolidone and macrocycles. [ABSTRACT FROM AUTHOR]

In the present study, the structure, thermal stability, conductive properties, and antimicrobial activity of silver(I) complexes with nitrile ligands were investigated. For the construction of the materials, 2‐cyanopyridine (2‐cpy), 4‐cyanopyridine (4‐cpy), 1,2‐dicyanobenzene (1,2‐dcb), and 1,3‐dicyanobenzene (1,3‐dcb) were used in addition to the silver nitrite and nitrate. Four new compounds were isolated and structurally characterized: one molecular complex [Ag4(1,2‐dcb)4(NO3)4], two 1‐D coordination polymers [Ag(2‐cpy)2(NO2)]∞, [Ag2(1,3‐dcb)2(NO3)2]∞, and one 3‐D coordination polymer [Ag(4‐cpy)(NO2)]∞. The results indicate that the nitrile complexes display good antimicrobial properties against the tested bacterial and fungal strains. The presence of weakly coordinating CN groups increases the release of silver ions into the bacterial and yeast cell environments. Moreover, these materials exhibit unusual electrical properties in thin‐layer devices. On the other hand, the nitrite and nitrate counterions give rise to the low thermal stability of the complexes. [ABSTRACT FROM AUTHOR]

We have investigated the relationship between the Ag concentration and the pn-junction depth in the Mg2Si pn-junction photodiodes fabricated by thermal diffusion of the Ag acceptor. The Ag concentration profiles and pn-junction depths in the samples annealed between 400 and 550 °C were studied by secondary ion mass spectroscopy and electron beam-induced current (EBIC) images. We observed two kinds of lattice diffusions of substitutional and interstitial Ag atoms with two different diffusion coefficients, of which activation energies were ∼0.97 and 0.75 eV, respectively. The depth of pn-junction observed by EBIC images increased with annealing temperature and annealing time. On the other hand, the average Ag concentration did not depend on the annealing time but depended on the annealing temperature. These results indicate that the average Ag concentration and pn-junction depth in Mg2Si photodiodes can be controlled by annealing temperature and annealing time, respectively. This study would contribute to the development of Mg2Si pn-junction photodiodes. [ABSTRACT FROM AUTHOR]

Schinus molle L. has been used as a folk medicine for many years. The aim of this study is to synthesize the silver nanoparticles, to identify them by spectroscopic techniques and to evaluate the antioxidant effects. In this study, Schinus molle was extracted with hexane, dichloromethane, ethyl acetate and methanol successively. After removal of the solvent from each extract by reduced pressure, the crude extracts were yielded. Methanol extract was used for synthesis of silver nanoparticles (s-AgNPs). The methanol extract dissolved in distilled water was treated with silver nitrate solution to produce the s-AgNPs. The extensive spectroscopic study enabled the identification of synthesized s-AgNPs. UV-Vis spectroscopic analysis presented the maximum absorption of s-AgNPs at 486 nm. The average particle size of s-AgNPs was measured as 77.6 nm by Scanning electron microscope (SEM). X-ray diffraction (XRD) pattern revealed that the nanoparticles were face-centered cubic structure. The slight differences between extract and AgNPs in FTIR spectrum proved the formation of s-AgNPs. In that, some functional group such as hydroxyl in the extract was oxidized while reduction of silver ions. Elemental analysis displayed the silver percentage to be 75.79 %w/w. Antioxidant activity study including DPPH, ABTS•+ and FRAP assays displayed the considerable effect of s-AgNPs. This is the first report to present the synthesis of silver nanoparticles from Schinus molle L. methanol extract and to evaluate the antioxidant activity. [ABSTRACT FROM AUTHOR]

Technique development for getting environmentally friendly nanomaterials was the paper's main goal. Spectroscopic techniques were utilized to characterize the plant extracts used in this work (UV-Vis, FTIR and Raman). In this case, plants from the Valea Voievozilor was processed in a dry state, was used at the ideal moment and at the plant's peak maturation period. Several analytical techniques (UV-Vis, FTIR, Raman analysis) have been used to analyze the nanoparticles (Ag) created with the aid of these plant extracts. Both the bioreduction of silver ions (Ag+ to Ag0) and the stability of silver nanoparticles are caused by the bioactive chemicals found in plant materials. [ABSTRACT FROM AUTHOR]

Biodegradable sponges are currently attracting significant attention; however, the development of safe materials with high levels of antimicrobial activity remains a major challenge. Doping with silver nanoparticles (AgNPs) can effectively solve this problem. In this study, pectin sponges (PE-S) and nano-silver pectin sponges (PE-S/Ag) were synthesized in situ by using the freeze-drying method. The prepared sponge samples were then characterized with various tools. UV‒Vis spectroscopy was used to investigate the in situ synthesis of the AgNPs, FT-IR spectroscopy and XPS were used to investigate changes in the functional groups of the sponge samples, and SEM images were used to confirm the homogeneous distribution of AgNPs in the PE-S/Ag sponge. Our results suggested that the physical and chemical properties of the PE-S/Ag sponges were better than those of the PE-S sponges. The water absorption levels of the PE-S/Ag and PE-S sponges were three times and twice as high as that of gauze, respectively. Antibacterial tests showed that the minimum inhibitory concentrations of the PE-S/Ag sponge were 42 and 83 µg/mL against Escherichia coli and Staphylococcus aureus, respectively. Cytotoxicity and coagulation assays showed that the two sponge samples were nontoxic to cells and had good coagulation effects. The silver ion (Ag+) release assay was used to analyse the pattern of Ag+ release from the PE-S/Ag sponges. [ABSTRACT FROM AUTHOR]

Silver nanoparticles have superior properties that attract much attention because they can increase their effectiveness and efficiency compared to their macroscopic size. Silver nanoparticles have several benefits, one of which is as an antibacterial agent. Synthesis of silver nanoparticles was carried out by reducing silver ions (Ag+) to uncharged silver (Ag0) using a reducing agent from Hibiscus sabdariffa Linn. petal extract. This research aims to synthesize silver nanoparticles by studying several parameters that influence their formation, such as the pH of Hibiscus sabdariffa Linn. petal extract, reaction time, silver nitrate concentration, and Hibiscus sabdariffa Linn. petal extract concentration. The silver nanoparticles formed were then tested for their antibacterial activity. The experimental results showed that the best synthesis was performed using Hibiscus sabdariffa Linn. petal extract with pH 10, reaction time of 45 minutes, silver nitrate concentration of 1×10-4 M, and Hibiscus sabdariffa Linn. petal extract concentration of 0.004%. The synthesized silver nanoparticles, examined through a transmission electron microscope, exhibited a size distribution ranging from 2 to 26 nm with an average size of 12 ± 3 nm, which was stable with a storage time of 3 months. Silver nanoparticles showed antibacterial activity against Staphylococcus aureus. Hibiscus sabdariffa Linn. petal extract is a promising reducing agent for producing antibacterial silver nanoparticles, showcasing its potential in this application. [ABSTRACT FROM AUTHOR]

The possibility of obtaining a biodegradable bactericidal composition containing silver nanoparticles by the reduction of silver ions using sodium carboxymethyl starch and UV irradiation has been investigated in this work. It is shown that the degree increase of substitution of carboxymethyl groups in NaCMS leads to an intensity increase of absorption of the surface plasma resonance bands of AgNP and an intensification of the Ag+ reduction process to Ag0. The intensity of the emerging Ag peak shows a complete reduction of Ag+ to Ag0 and the effectiveness of CMS in stabilizing the resulting AgNP. The results obtained from the EDX spectrum, together with the results of the SEM images, are strong evidence for the formation of AgNP nanoparticles and indicate the long-term colloidal stability of the product. It is shown that the processed nanocomposite solution AgCMS hosiery and non-woven materials have high antibacterial activity. [ABSTRACT FROM AUTHOR]

This study reports the successful fabrication of complex 3D metal nanoparticle–polymer nanocomposites using two‐photon polymerization (2PP). Three complementary strategies are detailed: in situ formation of metal nanoparticles (MeNPs) through a single‐step photoreduction process, integration of pre‐formed MeNPs into 2PP resin, and site‐selective MeNPs decoration of 3D 2PP structures. In the in situ formation strategy, a phase‐transfer method is applied to transfer silver and copper ions from an aqueous phase into a toluene solvent to disperse them in photoreactive monomers.The addition of a photosensitive dye, coumarin 30, facilitated the reduction of silver ions and improved the distribution of silver nanoparticles (AgNPs). This strategy is successfully used to produce other MeNPs, such as Cu and Au. The integration of pre‐formed MeNPs enabled highly controlled NP size distribution within the 2PP 3D structures with high‐fidelity To enable selective decoration of 2PP 3D surfaces with MeNPs, a multimaterial strategy is developed, with one of the resins designed for thiol‐ene reaction, which demonstrated selective binding to AuNPs. The successful development of complementary strategies for integration of MeNPs into 2PP resins offers exciting opportunities for fabrication of MeNP composites with sub‐micron resolution for applications from photonics to metamaterials and drug delivery. [ABSTRACT FROM AUTHOR]