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This report demonstrates the synthesis of a trihybrid system (PBI-NP-GO) consisting of perylene bisimide appended peptide (PBI-UW) nanofibers, silver nanoparticles (PBI-AgNP), and graphene oxide (GO) nanosheet. Tryptophan-containing PBI molecules in an aqueous medium can reduce silver ions into silver nanoparticles in the presence of sunlight to form a dihybrid system consisting of nanofibers and nanoparticles; the addition of GO into the dihybrid system ultimately leads to the formation of the trihybrid system. The trihybrid system was thoroughly characterized by various spectroscopic and microscopic techniques, such as ultraviolet-visible (UV-vis), Fourier transform-infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), RAMAN, and field emission transmission electron microscopy (FEG-TEM). The so-formed trihybrid system was successfully utilized as a potential photocatalyst for the reduction of carcinogenic Cr(VI) to non-toxic Cr(III) under irradiation with blue LED light. An almost complete reduction of Cr(VI) was achieved within 30 minutes of irradiation. Moreover, good photo-switching behaviour was observed with the highest photocurrent gain of 5.11 (Ion/Ioff) compared to PBI-AgNP (dihybrid) and PBI-UW, where Ion/Ioff values of 3.92 and 2.31, respectively, were obtained. The photocatalytic activity and photo-switching behaviour of the trihybrid system are due to efficient photo-induced charge separation. [ABSTRACT FROM AUTHOR]

The emergence of antibiotic-resistant bacteria necessitates the development of novel, sustainable, and biocompatible antibacterial agents. This study addresses cytotoxicity and environmental concerns associated with traditional silver nanoparticles (AgNPs) by exploring lignin, a readily available and renewable biopolymer, as a platform for AgNPs. We present a novel one-pot synthesis method for lignin-based AgNPs (AgNPs@AL) nanocomposites, achieving rapid synthesis within 5 min. This method utilizes various organic solvents, demonstrating remarkable adaptability to a wide range of lignin-dissolving systems. Characterization reveals uniform AgNP size distribution and morphology influenced by the chosen solvent. This adaptability suggests the potential for incorporating lignin-loaded antibacterial drugs alongside AgNPs, enabling combined therapy in a single nanocomposite. Antibacterial assays demonstrate exceptional efficacy against both Gram-negative and Gram-positive bacteria, with gamma-valerolactone (GVL)-assisted synthesized AgNPs exhibiting the most potent effect. Mechanistic studies suggest a combination of factors contributes to the antibacterial activity, including direct membrane damage caused by AgNPs and sustained silver ion release, ultimately leading to bacterial cell death. This work presents a straightforward, adaptable, and rapid approach for synthesizing biocompatible AgNPs@AL nanocomposites with outstanding antibacterial activity. These findings offer a promising and sustainable alternative to traditional antibiotics, contributing to the fight against antibiotic resistance while minimizing environmental impact. [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]

Many articles have already been published dealing with silver ions and its nanoparticles, but mostly from the environmental and toxicological point of view. This article is a review focused on the various analytical techniques and detection platforms used in the separation and determination of mentioned above species, especially on the trace concentration level. Commonly used are optical methods because of their high sensitivity and easy automation. The separation methods are mainly used for the separation and preconcentration of silver particles. Their combination with other analytical techniques, mainly inductively coupled plasma mass spectrometry (ICP-MS) leads to very low detection limits of analysis. The electrochemical methods are also powerful and perspective mainly because of the fabrication of new sensors designed for silver determination. All methods may be combined with each other to achieve a synergistic improvement of analytical parameters with an impact on sensitivity, selectivity and reliability. The paper comprises a review of all three types of analytical methods on the determination of trace quantities of silver ions and its nanoparticles. [ABSTRACT FROM AUTHOR]

The recovery and valorization of metals and rare earth metals from wastewater are of great importance to prevent environmental pollution and recover valuable resources. Certain bacterial and fungal species are capable of removing metal ions from the environment by facilitating their reduction and precipitation. Even though the phenomenon is well documented, little is known about the mechanism. Therefore, we systematically investigated the influence of nitrogen sources, cultivation time, biomass, and protein concentration on silver reduction capacities of cell‐free cultivation media (spent media) of Aspergillus niger, A. terreus, and A. oryzae. The spent medium of A. niger showed the highest silver reduction capacities with up to 15 μmol per milliliter spent medium when ammonium was used as the sole N‐source. Silver ion reduction in the spent medium was not driven by enzymes and did not correlate with biomass concentration. Nearly full reduction capacity was reached after 2 days of incubation, long before the cessation of growth and onset of the stationary phase. The size of silver nanoparticles formed in the spent medium of A. niger was influenced by the nitrogen source, with silver nanoparticles formed in nitrate or ammonium‐containing medium having an average diameter of 32 and 6 nm, respectively. [ABSTRACT FROM AUTHOR]

The surface-supported silver nanoparticles have been studied and applied in various applications. Many unique nanostructures have been introduced into this field to improve the functionalities of the surfaces depending on application purposes. We created featured silver nano-array surfaces by utilizing the solvent-mediated phase transition on the surface grafted with poly (acrylic) acids polymer chains and taking advantage of the low temperature of argon gas discharged plasma as a reducing agent. The applied solvents and grafted polymer chain densities affected the phase transition and thus determined the outcome of surface nano-array patterns. However, the total loaded silver ions on the surface affected silver nano-array structures at the sub-micron levels. The featured silver patterned surfaces made in the optimal conditions present a favorable surface-enhanced Raman spectroscopy enhancement as well as recyclability for detection re-usage. This novel method prepares tunable silver nanopatterned surfaces and provides a new approach to various potential applications. [ABSTRACT FROM AUTHOR]

Laminarin is a promising marine biopolymer that is abundant, non-toxic, and biodegradable. However, laminarin has a weak reduction potential for metal ions, resulting in the synthesis of a lower content of large-sized silver nanoparticles (AgNPs). Here, we showed that after the introduction of aldehyde groups, the reduction potential of laminarin increased, decreasing the synthesis time and increasing the density of AgNPs. 1H NMR and FT-IR confirmed the addition of aldehyde groups on laminarin. The dialdehyde-modified laminarin (DLAM) showed in situ , simple, and rapid synthesis of ultrasmall-sized spherical AgNPs (<10 nm), as revealed by TEM images. The aldehyde and carboxyl groups of DLAM act as synchronized reducing and anchoring agents. The conversion of Ag ions into AgNPs-DLAM was confirmed by UV–Vis spectrophotometer, FTIR, XRD, and XPS analysis. The AgNPs-DLAM showed significantly enhanced antibacterial activities than silver ions against Escherichia coli and Staphylococcus aureus via causing morphological changes and pore formations in bacterial cells. The AgNPs-DLAM also inhibited bacterial biofilm formation. In contrast, the AgNPs-DLAM showed negligible toxicity toward human keratinocytes. Furthermore, AgNPs-DLAM increased the migration of human keratinocytes, indicating efficient wound healing properties. Thus, signifying the importance of AgNPs-DLAM in clinical applications. • Laminarin has a weak reduction potential to reduce silver ions into AgNPs. • Dialdehyde modification of Laminarin increased its Ag+ reducing ability. • DLAM can rapidly reduce Ag+ into ultrasmall AgNPs by avoiding toxic chemicals and high temperatures. • Biofabricated AgNPs-DLAM exhibited potential antibacterial and wound healing properties. • AgNPs-DLAM might serve as a biocompatible dressing for the treatment of wounds. [ABSTRACT FROM AUTHOR]

Fluorescent materials based on aggregation-induced emission luminogens (AIEgens) have unique advantages for in situ and real-time monitoring of biomolecules and biological processes because of their high luminescence intensity and resistance to photobleaching. Unfortunately, many AIEgens require time-consuming and expensive syntheses, and the presence of residual toxic reagents reduces their biocompatibility. Herein, silver@quercetin nanoparticles (Ag@QCNPs), which have a clear core–shell structure, were prepared by redox reaction of quercetin (QC), a polyphenolic compound widely obtained from plants, including those used as foods, and silver ions. Ag@QCNPs show both aggregation-induced luminescence and the distinct plasma scattering of silver nanoparticles, as well as good resistance to photobleaching and biocompatibility. The Ag@QCNPs were successfully used for cytoplasmic labeling of living cells and for computerized tomography imaging in tumor-bearing mice, demonstrating their potential for clinical applications. [ABSTRACT FROM AUTHOR]

The good antimicrobial properties of silver make it widely used in food, medicine, and environmental applications. However, the release and accumulation of silver-based antimicrobial agents in the environment is increasing with the extensive use of silver-based antimicrobials, and the prevalence of silver-resistant bacteria is increasing. To prevent the emergence of superbugs, it is necessary to exercise rational and strict control over drug use. The mechanism of bacterial resistance to silver has not been fully elucidated, and this article provides a review of the progress of research on the mechanism of bacterial resistance to silver. The results indicate that bacterial resistance to silver can occur through inducing silver particles aggregation and Ag+ reduction, inhibiting silver contact with and entry into cells, efflux of silver particles and Ag+ in cells, and activation of damage repair mechanisms. We propose that the bacterial mechanism of silver resistance involves a combination of interrelated systems. Finally, we discuss how this information can be used to develop the next generation of silver-based antimicrobials and antimicrobial therapies. And some antimicrobial strategies are proposed such as the "Trojan Horse" - camouflage, using efflux pump inhibitors to reduce silver efflux, working with "minesweeper", immobilization of silver particles. [ABSTRACT FROM AUTHOR]

The development of antimicrobial polymers is a priority for engineers fighting microbial resistant strains. Silver ions and silver nanoparticles can assist in enhancing the antimicrobial properties of microcapsules that release such substances in time which prolongs the efficiency of antimicrobial effects. Therefore, this study aimed to functionalize different polymer surfaces with antimicrobial core/shell microcapsules. Microcapsules were made of sodium alginate in shell and filled with antimicrobial silver in their core prior to application on the surface of polymer materials by dip-coating methodology. Characterization of polymers after functionalization was performed by several spectroscopic and microscopic techniques. After the characterization of polymers before and after the functionalization, the release of the active substances was monitored in time. The obtained test results can help with the calculation on the minimal concentration of antimicrobial silver that is encapsulated to achieve the desired amounts of release over time. [ABSTRACT FROM AUTHOR]

Poly‐1‐vinyl‐1,2,4‐triazole (PVT)‐based materials with silver nanoparticles are promising antibacterial products. The metal nanoparticles with controllable sizes were obtained by radiation‐induced reduction of the dispersions of complexes of PVT with silver ions. Formation of the silver nanoparticles in aqueous suspensions irradiated at pH 6.0, 2.5, and 2.0 was studied using methods of UV–VIS spectroscopy and transmission electron microscopy. UV–VIS spectroscopy has detected a change in the efficiency of interaction between protonated or non‐protonated PVT units and the surface of silver nanoparticles. The interaction of macromolecules with the metal surface under different degrees of protonation of PVT functional groups afforded the nanoparticles with a narrow size distribution and an average size from 3 to 10 nm. An increase in the acidity also leads to a decrease in the ratio of the generation/growth of nanoparticles. The radiation approaches both provide the synthesis of the nanoparticles of controlled sizes and permits to obtain the nanocomposites containing no impurities of chemical reducing agents. The nanocomposites obtained exhibit high antibacterial activity against various bacterial strains, which depends on the size of silver nanoparticles. [ABSTRACT FROM AUTHOR]

The integration of silver nanoparticles (Ag NPs) with mesoporous silica nanoparticles (MSNs) protects the former from aggregation and promotes the controlled release of silver ions, resulting in therapeutic significance on cancer and infection. The unique size, shape, pore structure and silver distribution of silver mesoporous silica nanoparticles (Ag‐MSNs) embellish them with the potential to perform combined imaging and therapeutic actions via modulating optical and drug release properties. Here, we comprehensively review the recent progress in the fabrication and application of Ag‐MSNs for combination therapies for cancer and infection. We first elaborate on the fabrication of star‐shaped structure, core‐shell structure, and Janus structure Ag‐MSNs. We then highlight Ag‐MSNs as a multifunctional nanoplatform to surface‐enhanced Raman scattering‐based detection, non‐photo‐based cancer theranostics and photo‐based cancer theranostics. In addition, we detail Ag‐MSNs for combined antibacterial therapy via drug delivery and phototherapy. Overall, we summarize the challenges and future perspectives of Ag‐MSNs that make them promising for diagnosis and therapy of cancer and infection. [ABSTRACT FROM AUTHOR]

In this study silver nanoparticles were dispersed over polyaniline nanofibers (nPANI) by simple chemical reduction of silver nitrate in the presence of nPANI, and the prepared nPANI/Ag nanocomposite was employed for sensitive and cost‐effective non‐enzymatic detection of glucose using a modified carbon paste electrode. Detailed structural, crystallographic and morphological characterization of nPANI/Ag was carried out by means of Fourier‐transform infrared spectroscopy, X‐ray diffractometry and scanning electron microscopy. The enhancement of charge transfer of nPANI upon incorporation of Ag nanoparticles was confirmed by electrochemical impedance spectroscopy, and the electrocatalytic efficacy of the nPANI/Ag nanocomposite towards oxidation of glucose in alkaline medium was proven by cyclic voltammetry. Crucially, chronoamperometry demonstrated a linear response of the nPANI/Ag‐based glucose sensor over a wide range of glucose concentrations from 100 μM to 10 mM with a lowest detection limit of 1,3 μM. The sensor had a good selectivity for glucose in the presence of common interfering biomolecules. The sensor also had a shelf‐life of several days and the response was repeatable for up to nine individual measurements. [ABSTRACT FROM AUTHOR]

Wound dressings were prepared by using polyethylene terephthalate (PET) fabric as the base material. The functionality of the fabric was enhanced by alkaline hydrolysis. The hydrolysis of the fabric led to the formation of carboxyl groups on its surface. FTIR and contact angle measurements were carried out to monitor the chemical and physical changes on the fabric surface. Silver was immobilized on the fabric as the bioactive component. The fabric was characterized by EDX in mapping mode to observe distribution of silver on the fabric. PEG 600 used as carrier for silver ions to be loaded of the material surface. Antimicrobial studies of the fabric was carried out by zone of inhibition and colony reduction methods against E. coli and S. aureus. Bacterial adhesion was completely inhibited in silver immobilized samples. On the basis of observations from mechanical analysis, EDX, carboxyl content estimation, and antibacterial resistance we concluded that material was the most suitable sample to develop wound dressing. [ABSTRACT FROM AUTHOR]

• Influence of reactant concentration on the morphology of silver nanoparticles. • Mechanisms governing the nucleation and growth of silver nanocubes. • Impact of intermediates' interaction on the outcome of the reaction. The exceptional qualities of silver nanocubes make them ideal for diverse applications in healthcare, electronics, energy, and environmental protection. Studying their growth morphology is crucial for precise synthesis control, property optimization, and sustainable production methods.In this paper, silver nanocubes were prepared through the reduction of silver nitrate using polyvinylpyrrolidone and sodium chloride as additives, with ethylene glycol and polyethylene glycol serving as reducing agents and solvents. The size and shape of these nanoparticles are significantly influenced by the concentration of the precursor and the amount of water in the reaction mixture. These two factors play distinct roles in altering the nucleation and growth processes of the silver nanocubes. Specifically, the precursor concentration determines the rate of nucleation, thus impacting whether the nanoparticles grow through coalescence or Ostwald ripening. Conversely, the water content modulates the reduction rate of silver ions, which in turn dictates whether the reaction occurs under thermodynamic or kinetic control. This investigation enhances our comprehension of the nucleation and growth mechanisms associated with silver nanocubes and provides valuable insights for the one-pot synthesis of uniformly-sized silver nanoparticles, extending beyond the realm of silver nanocubes. [ABSTRACT FROM AUTHOR]

This study describes a simple one-pot photochemical method to synthesize triangular silver nanoprisms (T-AgNPs), for which a mixture of silver nitrate (AgNO 3) and citrate was irradiated with an ultraviolet-C (UVC) lamp reactor. We successfully synthesized T-AgNPs with edge lengths ranging from 50 to 150 nm, showing a significant localized surface plasmon resonance (LSPR) band over a wavelength of 1200 nm. This photochemical reaction appears to be unrestricted by plasmon resonance conditions, allowing for the formation of colloidal T-AgNPs with an LSPR band in the near-IR region. In addition, this new method does not require any highly reactive reducing agents or initially prepared silver seed solution. The reduction of Ag+ ions by citrate is induced by UVC light, and the nascent Ag first undergoes nucleation to form spherical or quasi-spherical silver nanoparticles (S-AgNPs). Subsequently, continuous irradiation with UVC light facilitates the transformation of these S-AgNPs into T-AgNPs. The growth kinetics of the nanoparticles with different reaction conditions were examined using ultraviolet–visible–near-infrared spectroscopy and transmission electron microscopy. This new method offers a simple, efficient, and cost-effective means to synthesize T-AgNPs with near-IR LSPR, contributing to wider applications in the fields of optoelectronics, spectroscopics, photovoltaics, etc. [Display omitted] • Triangular silver nanoprisms (T-AgNPs) with 50-150 nm edges were synthesized via seed-free UVC-assisted citrate reduction. • The photoreaction formed T-AgNPs with near-IR LSPR bands, unconstrained by plasmon resonance conditions. • The shape evolution of silver nanoparticles was monitored by recording time-dependent UV–Vis spectra and TEM images. [ABSTRACT FROM AUTHOR]

Poly(styrene@N‐isopropylmethacrylamide‐methacrylic acid) [P (St‐NM)] microgels were prepared via seed facilitated emulsion polymerization process. In situ reduction of silver ions was carried out to generate Ag nanoparticles in the voids of shell region of polymer microgels. Synthesized P (St‐NM) and Ag‐P (St‐NM) particles were characterized by UV–Vis spectroscopy, transmission electron microscopy (TEM), Fourier‐transformed infrared spectroscopy (FTIR), and X‐ray diffraction (XRD). The stability of Ag nanoparticles within P (St‐NM) system over the wide range of pH and temperature is also a part of this study. Thus, prepared Ag‐P (St‐NM) was tested for its catalytic efficiency against reduction of K2Cr2O7 using formic acid (FA) as reductant. Factors affecting catalytic efficiency of Ag‐P (St‐NM) system towards transformation of Cr+6 to Cr+3 were investigated. Other toxic chemicals can also be reduced using same catalytic system. [ABSTRACT FROM AUTHOR]

A wound on the skin is associated with a break in coating continuity due to physical damage, which if affected by certain microorganisms, can lead to septicemia and death in some cases. Biocompatible and bioactive materials with antimicrobial properties have been studied as potential platforms for wound healing. Bioactive glasses (BGs) are an example of such materials, and have recently been highlighted for soft tissue repair owing to their potential to accelerate healing processes and also act as carriers of therapeutic ions, such as silver (Ag); a well-known antimicrobial therapeutic agent. The aim of this study was to synthesize new spherical, submicron BG particles in the binary system SiO 2 –Ag 2 O, with different Ag contents, using a sol-gel based process. X-ray diffraction (XRD) revealed the formation of metallic silver, and morphological studies confirmed the presence of silver nanoparticles deposited on the spherical and mesoporous silica particles. Furthermore, evidence of Ag+ incorporation into the glass network was found using x-ray photoelectron spectroscopy (XPS) analysis, indicating that silver is present both as metallic silver nanoparticles and as a network modifier, incorporated into the glass structure. The sample also showed silver dissolution capability, confirming it as a potential platform for antimicrobial therapeutic agents. Thus, evaluations showed that submicron silver BG particles with antimicrobial properties can be synthesized using a simple and fast sol-gel based method, which maintains the silica's spherical morphology and yields particles that facilitate soft tissue repair. [ABSTRACT FROM AUTHOR]

The toxicity towards viruses of silver nanoparticles (AgNPs) has been reported to be dependent on several factors such as particle concentration, size, and shape. Although these factors may indeed contribute to the toxicity of AgNPs, the results presented in this work demonstrate that surface chemistry and especially surface charge is a crucial factor governing their antiviral activity. Here, this work investigated the influence of capping agents representing various surface charges ranging from negative to positive. These AgNPs were capped with citrate, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) mercaptoacetic acid (MAA) and (branched polyethyleneimine (BPEI). We show that AgNPs exhibited surface charge-dependent toxicity towards MS2 bacteriophages. Among the capping agents under investigation, BPEI capped AgNPs (Ag/BPEI) exhibited the highest reduction of MS2 resulting in ≥6 log10-units reductions, followed by 4–5 log10-units reductions with PVP and PEG capping's and 3–4 log10-units with MAA and citrate cappings. Bare nanoparticles reported a mere 1–2 log10-units reduction. Electrostatic interaction between the positively charged BPEI-coating and the negatively charged virus surface played a significant role in bringing the MS2 closer to toxic silver ions (Ag+). Further results obtained from TEM showed that Ag/BPEI nanoparticles could directly damage the structure of the MS2 bacteriophages. AgNPs and cationic capping agents' observed synergy can lead to much lower and much more efficient dosing of AgNPs for antiviral applications. [ABSTRACT FROM AUTHOR]

The antimicrobial bioactivity of silver nanoparticles is well known, and they can be used widely in many applications, becoming especially important in the biomedical industry. On the other hand, the electrospun nanofibers possess properties that can enhance silver nanoparticle applicability. However, silver nanoparticle bioactivity differs depending on the loading of silver ions into electrospun nanofibers. This review is aimed at comparing different silver incorporation methods into electrospun nanofibers and their antimicrobial activity, discussing each procedure's limitations, and presenting the most promising one. This review showed that the preferred techniques for incorporating silver nanoparticles were direct blending and ultraviolet irradiation methods due to their simplicity and efficient results. Besides, polyacrylonitrile nanofibers (PAN) have been the most reported system loaded with silver nanoparticles. Finally, independently of the technique used, silver nanoparticle-loaded nanofibers show high antimicrobial activity in all cases. [ABSTRACT FROM AUTHOR]

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the additive silver nanoparticles intended to be used in plastics. All the silver particles are in the size range of 1–100 nm, with about 15 nm mean diameter and 99% by number of particles below 20 nm. The additive is intended to be used as a surface biocide at up to 0.025% w/w in non-polar plastics for contact with a wide variety of foods, times, temperatures and food contact surface/mass of food ratios. The particulate form is maintained when the additive is incorporated into plastics, albeit with some aggregation/agglomeration observed. The data and information on theoretical considerations, on specific migration and abrasion tests show that, under the intended and tested conditions of uses, the silver nanoparticles stay embedded in the polymer, do not migrate and resist release by abrasion, thus, do not give rise to exposure via food and to toxicological concern. There is migration of silver in soluble ionic form up to 6 μg/kg food from the surface of the additive particles. This is below the group restriction of 50 μg silver/kg food proposed by the AFC Panel in 2004 and would lead to a maximum exposure from FCM that would be below the acceptable daily intake (ADI) of 0.9 μg silver ions/kg body weight (bw) per day established by ECHA. Therefore, the Panel concluded that the substance does not raise safety concern for the consumer if used as an additive at up to 0.025% w/w in polymers, such as polyolefins, polyesters and styrenics, that do not swell in contact with aqueous foods and food simulants. The Panel noted, however, that exposure to silver from other sources of dietary exposure may exceed the ADI set by ECHA. [ABSTRACT FROM AUTHOR]

Prostate-specific antigen (PSA), a glycoprotein that is most likely to cause prostate cancer, has attracted widespread attention in recent years due to its increasing threat to people's lives and health. Herein, we developed a new signal-amplified photoelectrochemical (PEC) immunosensing method for quantitative monitoring of the target PSA based on the ion-exchange reaction for the in situ formation of ZnO/CdS/Ag2S nanohybrids triggered by the as-released silver ions (Ag+) from silver nanolabels. Initially, the introduction of a target PSA caused the formation of a sandwich immunocomplex in an anti-PSA capture antibody (cAb)-coated microplate with the help of a silver nanoparticle-labeled detection antibody (AgNPs-dAb). Thereafter, the introduced AgNPs were dissolved with acid to release numerous silver ions. In this regard, an ion-exchange reaction occurred between the silver ions and ZnO/CdS nanorods on the photosensitive electrode, thus producing ZnO/CdS/Ag2S nanohybrids to generate a relatively strong photocurrent. Under optimal conditions, the ion-exchange reaction-based PEC immunoassay exhibited a good linear range of 0.05–50 ng mL−1 and allowed the detection of the target PSA at a concentration as low as 0.018 ng mL−1. In addition, the PEC immunoassay displayed satisfactory repeatability, high specificity, and acceptable method accuracy. Importantly, the ion-exchange reaction-based PEC immunoassay provides a new perspective for the detection of other disease-related biomarkers by controlling the corresponding antibodies. [ABSTRACT FROM AUTHOR]

Thiol functionalized magnetic silica-core shell (MPTES-Fe3O4@SiO2) is used in the colorimetric sensor for the recognition of silver ions. This detected system acts more sensitive and selectively for silver ions in real-time applications. Thiol functionalized core-shell magnetic nanoparticles interact with silver ions to form a metal-thiol complex with the appearance of yellow color in the solution with surface resonance peak (403cm-1) in UV spectra. This colorimetric sensor is very cheap, and facile in the detection of a silver ion with the lower limit of the detection value of 10 nm. Furthermore, we have applied for the monitoring of the real samples of this sensing system with good recovery results. [ABSTRACT FROM AUTHOR]

In the present study, a novel silver nanoparticles-decorated three-dimensional graphene-like porous carbon (Ag/3D GPC) nanocomposite has been synthesized via the method of carbonization and reduction of silver ions at the same time. This Ag/3D GPC nanocomposite possess an interconnected network of well crystalized and submicron-sized macropores with thin graphene walls of several nanometers, where silver nanoparticles distributing uniformly. The water based and ethylene glycol based Ag/3D GPC hybrid nanofluids have been prepared without any surfactant. The hybrid nanofluids with low concentration (<0.8 wt%) can be steadily dispersed for more than six months. The thermal conductivity enhancement for the nanofluids with 0.1 wt% can reach 10.3% and 8.8% at 25 °C compared with pure water and ethylene glycol, respectively. The viscosity of nanofluids is investigated, the temperature dependence of the dynamic viscosity obeys an Arrhenius-like behavior. The prepared Ag/3D GPC hybrid nanofluids with good stability and thermal conductivity are promisingly considered to be used in heat transfer field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interface concentration gradient drives the growth of dendritic structures. • The interface diffusion gradient is quantified by Mach-Zehnder interferometer. • A regulation of interface gradient leads to the formation of silver dendrites. • Further regulation of the gradient results in the formation of diverse silver structures. • The general formation mechanism of dendritic structures is discussed. Dendritic structures are widely present in nature, from river networks to snowflakes. There is a long-term interest in discovering their common formation mechanism, especially the driving force leading to the branching and the reason to keep symmetry. The inhibition of lithium dendrites in secondary batteries also calls for the deep understanding on the formation of dendritic structures. Here in this article, we report an investigation on the driving force of the formation of dendritic structures. Silver particles are synthesized by Galvanic replacement reaction (GRR) in which metal rods are immersed into the silver nitrate solution to reduce silver ions followed by silver particles formation on the surface of rods. The silver ions concentration profile near the rods is measured by Mach-Zehnder interferometer during the reaction. It is found that the formation of silver dendritic particles is accompanied by the interface concentration gradient. A regulation on the gradient leads to the change of silver morphology, experimentally confirming the dominant role of the interface concentration gradient in the formation of diverse structures. [ABSTRACT FROM AUTHOR]

• Chitosan-silver polymeric scaffolds were highly porous and biodegradable. • It was found to cytocompatible and supported growth of osteoblasts. • It enhanced osteogenic differentiation and matrix mineralization. • It upregulated the expression of osteogenic differentiation marker genes. • The scaffold is suitable for bone tissue engineering applications. Scaffolds fabricated with only chitosan (CS) as base polymer is limited by its fast degradation rate, reduced mechanical strength and diminished bioactivity. To achieve optimal properties suitable for bone tissue engineering, CS based scaffolds are developed by addition of copolymers, nanoparticles, and functional group modifications. In our study, biodegradable composite scaffolds were fabricated by utilizing CS and silver nanoparticles (AgNPs) were in-situ synthesised on CS matrix with no external reducing agent. The scaffold was investigated for its suitability to be employed in bone tissue engineering (BTE) applications. The scaffolds were found to be highly porous and possess the ability of hydration, adsorb proteins and biomineralization. Chelation with silver ions greatly improved the properties of CS scaffolds by controlling swelling and degradation rate. In addition this, the scaffolds were found to exert broad spectrum antibacterial activity. Furthermore, the scaffolds are highly biocompatible and supported the growth of osteoblast. It also promoted osteogenic differentiation by upregulating Runt-related transcription factor 2 (Runx2), Type-1 collagen (Col-I), Alkaline phosphatase (ALP) activity and secreted Osteocalcin (OC) levels. Among the synthesized scaffolds, CS-Ag 1.5 M scaffold was found to be superior and suitable for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

Sliver nanoparticles (Ag NPs) are produced industrially and commercially available in recent time. Silver and its nanoparticles are widely applied to consuming medical purposes. Silver nanoparticles are able to resemble cellular components and typical proteins, which helps the nanoparticles to cross natural barriers in human body. For this reason, the current study was designed to investigate the damage caused by silver nanoparticles, especially in liver which is one of the most targeted organs of nanoparticles as a result of their accumulation and damages caused in various aspects such as tissue, functional ability and DNA of liver cells. 30 albino male rats were used for this study and were divided into 3 main groups. The first group represented control and a normal saline solution was given, while the second group was given silver nanoparticles at a concentration of 2 mg/kg of body weight, and the third group was given silver nanoparticles at a concentration of 3 mg/kg of body weight. Each concentration of Ag NPs was dissolved in 3 mL of the normal saline and given directly to the experimental animal's stomach by feeding tube with diameter of 0.6 cm and every day for 10 weeks. The results in the current study showed histopathological change in liver tissue such as large granulomatous lesion with an increase in macrophage numbers, as also shown by necrotic hepatocytes with dilation of sinusoids. The deformation of architecture in the parenchyma appeared in both concentrations. The biochemical parameters investigation in the liver clarified increased level of enzymes accordance with doses of Ag NPs. The damage was identified in DNA of hepatocytes by comet assay and the degree of damage was evident through increasing the numbers of tailed nuclei and in strand breaks of DNA. The reactive oxygen species (ROS) generation had a key role in the events of structural and functional disorders in the liver of experimental animals. [ABSTRACT FROM AUTHOR]

A gold electrode was modified with cysteamine by a self-assembly monolayer technique and covalently coupled with 3-mercaptopropionic acid functionalized silver nanoparticles. The free carboxylic acid groups of the 3-mercaptopropionic acid functionalized silver nanoparticles assembled on gold electrode were bonded with the amine groups of biotin or avidin trough amide linkages. The changes in the interfacial properties of gold electrode modified stepwise were examined by cyclic voltammetry and electrochemical impedance spectroscopy using the ferric/ferrous redox system. The electrochemical sensing properties of covalently bonded biotin or avidin on a gold electrode modified with silver nanoparticle were studied by cyclic voltammetry and electrochemical impedance spectroscopy by the varying concentrations of the bio-affinity molecules in the same redox system. The charge transfer resistance was directly proportional to the concentration of analyte while the response was weakly dependent upon the change in the respective peak anodic currents. The sensing mechanism was established to explain the role of the silver nanoparticles. [ABSTRACT FROM AUTHOR]

• Hydride generation was used as a sample pretreatment procedure for the colorimetric system. • Visual colorimetric and smartphone detection was applied for As(III) detection. • The reaction mechanism of Ag-BTC and AsH 3 was proposed and discussed. • As(III) concentration as low as 10 μg/L could be detected by this system. The reaction mechanism of Ag-containing metal organic framework (Ag-BTC) and hydrogen arsenide (AsH 3) was discussed in detail in this work. Silver ions in Ag-BTC were reacted with AsH 3 , and silver nanoparticles were generated on the surface of Ag-BTC, causing its color changed. This property was further applied to a hydride generation-colorimetric analytical system. As(III) was converted to AsH 3 via hydride generation and then reacted with the Ag-BTC (immobilized on test paper), leading to the test paper changed from white to black. Visual colorimetric and smartphone RGB readout mode were used for this analytical system. The results could be readout by naked-eye in visual colorimetric mode and a smartphone in RGB readout mode. Under the optimized conditions, As(III) concentration as low as 10 μg/L and 50 μg/L could be readout by smartphone and naked-eye, respectively. This method was further successful applied to As(III) determination in real samples (drinking water samples and scented tea samples), with recoveries of 91–113%. [ABSTRACT FROM AUTHOR]

Osteogenesis surrounding dental implants is initiated by a series of early physiological events, including the inflammatory response. However, the persistence of an anti-infection surface often results in compromised histocompatibility and osseointegration. Here, we presented a programmed surface containing both silver nanoparticles (AgNPs) and silver ions (Ag+) with a heterogeneous structure and time-dependent functionalities. The AgNPs were located at the surface of the heparin-chitosan polyelectrolyte coating (PEM), whereas Ag+ was distributed at both the surface and inside of the coating under optimized conditions (pH=4). The optimized coating (Ag-4) exhibited potent bactericidal activity at the early stage (12 and 24 h after inoculation) and a sustained antibacterial efficacy in the subsequent stage (one or two weeks), as it gradually depleted. Furthermore, compared to coatings with sustained high silver concentrations in bacteria-cell coculture experiments, the degradable Ag-4 coating demonstrated improved cytocompatibility, better cell viability, and morphology over time. At a later stage (within one month), the in vivo test revealed that Ag-4-coated titanium had superior histocompatibility and osteogenesis outcomes compared to bare titanium in a bacteria-exposed environment. The programmed surface of dental implants presented in this study offers innovative ideas for sequential antibacterial effects and osseointegration. [Display omitted] • A programmed surface is designed and fabricated for bacteriostatic and osteogenic regulation. • The degradation of PEM coating enables a sequential release of AgNPs and Ag+. • Initially, the potent bactericidal effect was achieved by the presence of AgNPs. • Afterwards, the sustained release of Ag+ created a mild antibacterial environment with favorable cytocompatibility. • Finally, the thoroughly exposed porous titanium surface supported osseointegration well. [ABSTRACT FROM AUTHOR]

We report the synthesis and crystal structure of ethylphenyl dithiocarbamato silver(I) complex. The compound crystallized as [Ag4(EtphDTC)4] in which four Ag(I) ions and four molecules of ethylphenyl dithiocarbamato ligands constitute the metal cluster in the asymmetric unit. Each ethylphenyl dithiocarbamato ligand in the cluster is bonded to three Ag(I) ions through the sulfur atoms with one sulfur covalently bonded while the other sulfur atoms act as two electrons-three centres within the metal cluster. Each Ag(I) ion is linked to three Ag(I) ions through Ag–Ag metallic bond distance of 2.9115(3) Å and 3.0376(4) Å. The complex was thermolyzed at 120, 180 and 220 °C as single source precursor to prepare silver sulfide nanoparticles. Powder XRD patterns confirmed the as-prepared silver sulfide nanoparticles as acanthite Ag1.93S irrespective of the thermolysis temperature. TEM images of the silver sulfide nanoparticles showed particle of 2.99 nm for AgS1 nanoparticles obtained at 120 °C, 6.71 nm for AgS2 obtained at 180 °C and HRTEM image of AgS3 obtained at 220 °C showed average particle size of 32.90 nm. The results showed that the particle sizes of the as-prepared silver sulfide nanoparticles increases with thermolysis temperature. The as-prepared silver sulfide nanoparticles have spherical shapes irrespective of thermolysis temperature. [ABSTRACT FROM AUTHOR]

A comparative analysis has been performed for silver nanoparticle dispersions obtained by the chemical reduction of Ag+ ions using several samples of chitosan with different molecular masses as reductants and stabilizers. The structure and conductivity of ring deposits resulting from the evaporation of droplets of the obtained dispersion have been studied. It has been shown that the average size of silver nanoparticles, their number concentration, and the degree of precursor reduction weakly depend on chitosan molecular mass, while the geometric parameters and electrical conductivity of the ring deposits substantially change upon the passage from oligochitosans to high-molecular-mass chitosan. [ABSTRACT FROM AUTHOR]

A paper-based visual fluorescence immunoassay is presented for the detection of matrix metalloproteinase-7 (MMP7) that is related to renal cancer. The method is based on the distance-dependent fluorescence quenching of CdTe quantum dots (QDs) on a nitrocellulose membrane by Ag+ following a sandwich-type immunoreaction on microtiter wells using silver nanoparticle (AgNP)–labeled secondary antibody– and primary antibody–coated microtiter wells. The silver nanoparticles captured in the well are dissolved with HNO3, while the quenching effect of QDs is based on silver ion-exchange reaction under 365-nm excitation light irradiation. Increasing concentration of released Ag+, thus higher concentration of the protein, leads to an increased distance of quenching on the nitrocellulose membrane. The paper-based immunoassay by combination of AgNP-assisted ion-exchange reaction with QD gives good distance-dependent responses and allows the detection of MMP7 at a concentration as low as 7.3 pg mL−1. The coefficients of variation are less than 6.9% and 12.4% for intra-assay and inter-assay, respectively. High specificity and long-term stability are achieved during the assay. Importantly, the testing of human serum samples using our strategy shows well-matched results with commercial human MMP7 ELISA kits. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) catalyze the mild reaction between the weak reducing agent kojic acid (KA) and silver ions (Ag+) to form Au@Ag bimetallic NPs by the combination of the intrinsic catalysis with plasmonic properties This is proposed as a novel optical assay to determine the tyrosinase (TYRase) concentration. The nanoparticles have been characterized by UV-vis spectroscopy, transmission electron microscope (TEM) images, and X-ray photoelectron spectroscopy (XPS). The sensing mechanism is based on the fact that KA binds to TYRase by chelating with dicopper active site of TYRase and the introduction of TYRase restrains the Au@Ag bimetallic NP formation by the precedent binding with KA. A clear color variation from yellow to pink and UV-vis spectral changes are observed at the optimal wavelength of 410 nm. The assay works in the range 0.13~0.73 U mL−1 with a detection limit (LOD) of 0.019 U mL−1. The impact from matrix interfering substances including glucose, uric acid, common oxidases, and amino acids is negligible. The applicability is demonstrated by quantitative determination of TYRase in human serum samples with 74 to 89% recovery and RSD less than 4.0%, which accords with the level for bio-sample analysis. [ABSTRACT FROM AUTHOR]

The fact that the wounds infected by bacteria are difficult to heal is a major health issue. Herein, we synthesized silver nanoparticle-loaded polypeptide nanogels via an in situ method using UV irradiation, which is a relatively green and simple method. The size of the nanogel and silver nanoparticles could be regulated by changing the concentrations of the polypeptide and silver ions, respectively. Because the polypeptide PC10ARGD was histidine-rich and biodegradable, the as-synthesized silver nanogels exhibited low toxicity and good biocompatibility. The in vitro antibacterial experiments showed that the silver nanogels presented excellent antibacterial activity against both Gram-negative and Gram-positive bacteria. Moreover, silver nanogels had a good effect as an antibacterial and wound healing agent in vivo. These findings provide a new strategy and theoretical basis for the synthesis and application of silver nanoparticles. [ABSTRACT FROM AUTHOR]

Using mulberry silkworm pupae as an alternative source of renewable raw materials, a water-soluble Bombyx mori chitosan derivative N-carboxymethylchitosan is synthesized. A method for the photochemical reduction of silver ions into silver nanoparticles in an N-carboxymethylchitosan matrix is developed. The presence of silver nanoparticles in a colloidal solution is confirmed by UV spectroscopy, and their shape and size are determined by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Magnetic MnFe 2 O 4 nanoparticles containing 0, 1 and 3 at.% silver, respectively were synthesized by one-pot sol-gel method for antibacterial applications in biomedical fields. Material characterizations indicate that MnFe 2 O 4 begins crystallization at 134 °C and oxidation at 450 °C, the grain size and agglomeration degree increase with the silver content and silver exists as metallic state for the particles. The saturation magnetization decreases with the sintering temperature and slightly increases with the silver content, with the maximum of 50.0 emu/g obtained. Antibacterial tests by plate counting and PI-Hoechst 33342 staining suggest that the antibacterial activity of Ag–MnFe 2 O 4 nanoparticles is silver content-dependent. Silver ions concentration measurement, β-galactosidase activity assay and transmission electron microscopic observation show that the antibacterial activity is dominated by the actions of the released silver ions, rather than the membrane cell impairment or reactive oxygen species-induced oxidative stress mechanism. MC3T3-E1 cell test demonstrates the best cytocompatibility of the nanoparticles with 3 at.% silver, which is likely related to the reduced cell endocytosis of the aggregated particles. The combination of magnetism, antibacterial activity and biocompatibility would make Ag–MnFe 2 O 4 nanoparticles a potential multi-functional material in various biomedical applications. [ABSTRACT FROM AUTHOR]

Herein, we described the modification of chitosan with cyanuric chloride as a mediator for preparation of chitosan-s-triazinyl-bis(2-aminomethylpyridine) and chitosan-s-triazinyl-bis(8-oxyquinoline) derivatives to be used as reagents for preparation of silver nanoparticles under ecofriendly conditions. These two reagents are convenient and effective for reduction of silver ions to silver nanoparticles with particle size less than 10 nm that might be suitable for industrial and medicinal applications. The formation and particle size of AgNPs are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray analysis (EDX). The antimicrobial activity of the two modified chitosan-s-triazine-AgNPs was evaluated against activities against Gram-positive bacteria (M. luteus ATCC 10240 and MRSA ATCC 43300), Gram-negative bacteria (E. coli ATCC 25922 and P. aeruginosa ATCC 75853), and C. albicans. The results showed that chitosan-s-triazinyl-bis(2-aminomethylpyridine) AgNPs showed high antimicrobial activities against all the tested microorganisms, while their analogous chitosan-s-triazinyl-bis(8-oxyquinoline) AgNPs showed moderate activities. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) have been wildly used in agriculture, cosmetics, medicine, and food conservation fields due to their excellent antibacterial activity. The growing use of AgNPs products results that they can be inevitably released into the environment. Additionally, silver (Ag+) can easily find its way to the environmental waters from AgNPs. To gain deep insight into the transformation between AgNPs and Ag+ in the organisms or environment, and evaluate the toxicity of AgNPs and Ag+, various speciation analysis methods are developed. This paper presents a brief and systemic review for the speciation analysis of AgNPs and Ag+ based on the recently developed separation techniques coupled with atomic spectroscopy, including extraction method, chromatographic method, cation exchange reaction (CER) and single particles (SP) detection. Future perspectives in this field are also discussed. [ABSTRACT FROM AUTHOR]

This study employed NMR metabolomics to characterize macrophage responses to subtoxic concentrations of silver nanoparticles (AgNPs ca. 30 nm) and ionic silver (Ag+), with a view to further elucidate their immunomodulatory activity at the cell metabolism level. Exposure to AgNPs caused RAW 264.7 macrophages to decrease intracellular glucose utilization, possibly due to interference with glycolytic enzymes, and to reprogram the TCA cycle towards anaplerotic fueling and production of anti‐inflammatory metabolites (e.g. itaconate and creatine). Moreover, AgNPs‐exposed cells were able to control the levels of reactive oxygen/nitrogen species (ROS/RNS), likely through upregulation of glutathione synthesis. On the other hand, macrophages exposed to Ag+ at equivalent subtoxic concentrations showed reduced metabolic activity, lower ability to counterbalance ROS/RNS and alterations in membrane‐related lipids. Overall, the metabolomics approach hereby employed provided novel insights into the differential effects of AgNPs and Ag+, which help explain the lower toxic potential of nanosilver than silver ions. [ABSTRACT FROM AUTHOR]

Hydrogels containing silver nanoparticles (AgNPs) were recently found to exhibit excellent antibacterial properties against both gram-negative/positive bacteria and fungi. In this study, we reported the synthesis of AgNPs-contained gelatin-polyethylene glycol-dopamine (AgNP-GPD) hydrogels via the in situ formation of AgNPs in GPD polypeptide solution, followed by an enzymatic cross-linking reaction to form hydrogels. The experimental results showed that the reducing reaction exerted by GPD polypeptides under physiological conditions can afford the formation of AgNPs in situ in the polypeptide solution without the need for additional reducing agents and/or processes such as UV or thermal treatments and then the hydrogelation of GPD polypeptide solution containing AgNPs were preceeded via enzymatic cross-linking reaction. It was found that the gelation time, hydrogel mechanical property, degree of swelling and degree of enzymatic degradation for both GPD and AgNP-GPD hydrogels can be tuned by varying enzyme/oxidative agent concentration, catechol content, and reducing reaction conditions such as reaction time and silver ion concentration. Importantly, AgNP-GPD hydrogels exhibit excellent antibacterial properties against gram-negative and gram-positive bacteria. This type of hydrogel is a promising biomaterial for biomedical applications including wound healing and tissue engineering. [ABSTRACT FROM AUTHOR]

Recently revised OECD inhalation toxicity testing guidelines require measurements of lung burden immediately after and for periods following exposure for nanomaterials. Lung burden is a function of pulmonary deposition and retention of nanoparticles. Using lung burden studies as per OECD guidelines, it may be possible to assess clearance mechanisms of nanoparticles. In this study, male rats were exposed to silver nanoparticle (AgNP) aerosols (18.1–19.6 nm) generated from a spark generator. Exposure groups consisted of (1) control (fresh air), (2) low (31.2 ± 8.5 µg/m3), (3) moderate (81.8 ± 11.4 µg/m3), and (4) high concentrations (115.6 ± 30.5 µg/m3). Rats were exposed for 6-h/day, 5-days/week for 4 weeks (28-days) based on the revised OECD test guideline 412. Bronchoalveolar lavage (BAL) fluids were collected on post-exposure observation (PEO)-1 and PEO-7 days and analyzed for inflammatory cells and inflammatory biomarkers. The lung burdens of Ag from AgNPs were measured on PEO-1, PEO-7, and PEO-28 days to obtain quantitative mass concentrations per lung. Differential counting of blood cells and inflammatory biomarkers in BAL fluid and histopathological evaluation of lung tissue indicated that exposure to the high concentrations of AgNP aerosol induced inflammation at PEO-1, slowly resolved at PEO-7 and completely resolved at PEO-28 days. Lung burden measurement suggested that Ag from AgNPs was cleared through two different modes; fast and slow clearance. The fast clearance component was concentration-dependent with half-times ranging from two to four days and clearance rates of 0.35–0.17/day−1 from low to high concentrations. The slow clearance had half-times of 100, 57, and 76 days and clearance rates of 0.009, 0.012, and 0.007/day−1 for the high, moderate and low concentration exposure. The exact mechanism of clearance is not known currently. The fast clearance component which was concentration-dependent could be dependent on the dissolution of AgNPs and the slow clearance would be due to slow clearance of the low dissolution AgNPs secondary particles originating from silver ions reacting with biogenic anions. These secondary AgNPs might be cleared by mechanisms other than dissolution such as mucociliary escalation, translocation to the lymphatic system or other organs. [ABSTRACT FROM AUTHOR]

By using the method of cyclic voltammetry, we study the anodic dissolution of silver in a sodium polyacrylate (NaPA) solution. The influence of the concentration of NaPA, temperature, and рН value of the solution on the electrochemical characteristics of silver in the process of its polarization in a solution is investigated. It is shown that, for E = 0.3–1 V, the dissolution currents of silver become much stronger as the polyacrylate concentration increases. The diffusion character of anodic currents within the temperature range 20–50°С is established. It is discovered that, under the conditions of cathodic polarization (E = 0.15 V), silver ions are reduced with the formation of nanoparticles (7–10 nm). We propose to use the procedure of anodic dissolution of silver in order to get polyacrylate complexes of silver, which are precursors for the synthesis of stabilized silver nanoparticles. [ABSTRACT FROM AUTHOR]

Non‐spherical Au/Ag nanoparticles can be generated by chemical reduction of silver ions in the presence of preformed gold nanoparticles. The process of particle formation can be controlled by concentrations of ligands and reducing agent. The formation of ellipsoidal, nanorod‐ and peanut‐shaped nanoparticles as well as of more complex fractal nanoassemblies can be explained by changes in particle surface state, electrochemical potential formation and particle‐internal self‐polarization effects. It is possible to create highly fractal nanoassemblies with sizes between the mid‐nanometer and the lower micrometer range. The assemblies are marked by high optical absorption and complex nano‐networks of very high surface‐to‐volume ratios and a granular base structure. [ABSTRACT FROM AUTHOR]

Currently, green nanotechnology-based approaches using waste materials from food have been accepted as an environmentally friendly and cost-effective approach with various biomedical applications. In the current study, AgNPs were synthesized using the outer peel extract of the fruit Ananas comosus (AC), which is a food waste material. Characterization was done using UV–visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. The formation of AgNPs has confirmed through UV–visible spectroscopy (at 485 nm) by the change of color owing to surface Plasmon resonance. Based on the XRD pattern, the crystalline property of AgNPs was established. The functional group existing in AC outer peel extract accountable for the reduction of Ag+ ion and the stabilization of AC-AgNPs was investigated through FT-IR. The morphological structures and elemental composition was determined by SEM and EDX analysis. With the growing application of AgNPs in biomedical perspectives, the biosynthesized AC-AgNPs were evaluated for their antioxidative, antidiabetic, and cytotoxic potential against HepG2 cells along with their antibacterial potential. The results showed that AC-AgNPs are extremely effective with high antidiabetic potential at a very low concentration as well as it exhibited higher cytotoxic activity against the HepG2 cancer cells in a dose-dependent manner. It also exhibited potential antioxidant activity and moderate antibacterial activity against the four tested foodborne pathogenic bacteria. Overall, the results highlight the effectiveness and potential applications of AC-AgNPs in biomedical fields such as in the treatment of acute illnesses as well as in drug formulation for treating various diseases such as cancer and diabetes. Further, it has applications in wound dressing or in treating bacterial related diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiO 2 nanotubes (TiO 2 NTs), were formed by anodization onto Ti surface. • Au or Ag nanoparticles were electrodeposited onto Ti/TiO 2 NTs from reline. • Nucleation and growth mechanism of these NPs and its corresponding kinetics were analyzed. • From this analysis the electroactive surface area of the Ti/TiO 2 NTs electrode was estimate. In this work it is reported, for the first time, the electrochemical modification of titanium dioxide (TiO 2) nanotubes (NTs), previously formed onto a titanium metal surface (Ti/TiO 2 NTs) by anodization in an aqueous solution containing glycerol and ammonium fluoride, NH 4 F, with gold (AuNPs) or silver (AgNPs) nanoparticles (NPs) electrodeposited from their respective metallic ions dissolved in reline deep eutectic solvent. The nucleation and growth mechanism of these NPs and its corresponding kinetics were assessed from analysis of experimental potentiostatic current transients (i-t plots). In both cases, it was found that formation of the metal nanoparticles, MeNPs, occurs by multiple three-dimensional nucleation with diffusion-controlled growth. The surface of the MeNPs modified Ti/TiO 2 NTs were characterized by XRD, SEM and XPS that allowed to demonstrate the formation of quasi spherical MeNPs formed by metallic gold or metallic silver, that in general depicted 100 nm average diameter. [ABSTRACT FROM AUTHOR]

Improved bone bonding ability and antibacterial activity are two critical requirements for implants. In this work, novel dual surface modifications of dealloying and polydopamine/silver coating on a NiTi alloy were conducted. Scanning electron microscopy (SEM) results show a porous layer with interconnected micro- and nano-pores on the dealloyed NiTi alloy. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results confirm the formation of a polydopamine/silver coating on the surface of the dealloyed NiTi alloy. The silver nanoparticles (58.9 nm, in the polydopamine/silver coating) on the dealloyed NiTi alloy surface are smaller when compared with pristine NiTi alloy (73.1 nm). Moreover, the dealloyed NiTi alloy with polydopamine/silver coating exhibits better antibacterial activity against Escherichia coli (99.7%) and Staphylococcus aureus (99.4%) than pristine NiTi alloy with the same coating (97.3% and 96.5%, respectively), due to the larger surface area, higher silver content, and smaller silver nanoparticles that trigger more silver ion release. The combined dealloying and coating method is an effective way of increasing antibacterial activity of NiTi alloys. The findings presented in this work may provide a new guidance for the surface modification of NiTi implant materials. [Display omitted] • Dual surface modifications of dealloying and polydopamine/silver coating were conducted on NiTi alloy. • The NiTi alloy was first dealloyed followed by coating antibacterial polydopamine/silver. • The dual-surface-modified NiTi alloy shows smaller silver nanoparticles and releases more silver ions. • The dual-surface-modified NiTi alloy exhibits better antibacterial activity than bare NiTi alloy. [ABSTRACT FROM AUTHOR]

Heavy metals released by anthropogenic activities are extremely toxic to animals and plants due to their bioaccumulative and persistent environmental presence. In the current study, silver nanoparticles (AgNPs) were synthesized utilizing eco-friendly processes, and their potential in colorimetric Hg2+ ion sensing in environmental samples was examined. An aqueous extract of Hemidesmus indicus root (Sarsaparilla Root, ISR) rapidly converts silver ions into AgNPs within 5 min of exposure to sunlight. Transmission electron microscopy confirms that ISR-AgNPs are spherical, ranging from 15 to 35 nm. Fourier-transform infrared spectroscopy revealed phytomolecules stabilized the NPs with hydroxyl and carbonyl substituents. The ISR-AgNPs detect Hg2+ ions by a colour change that can be seen with the naked eye within 1 min. The probe is interference-free and detects the presence of Hg2+ ions in sewage water. A method for fabricating ISR-AgNPs onto paper was disclosed, and this portable ISR-AgNPs embedded paper device was found to be good at sensing mercury present in the water. The findings show that environmentally friendly synthesized AgNPs can contribute to developing onsite colorimetric sensors. [Display omitted] • Rapid silver nanoparticles synthesis using sunlight and Hemidesmus indicus root extract. • Phytochemicals stabilize the AgNPs. • Paper fabricated with AgNPs sense mercury with good selectivity. • AgNPs disrupt bacterial membranes and kill them. [ABSTRACT FROM AUTHOR]

Recently the use of medicinal plants potential in the production of nanoparticles has received serious attention. Here, the main component of Camellia sinensis L. (green tea) extract was detected by spectroscopy and the optimal conditions were determined for their performance in green synthesis of silver nanoparticles at room temperature. Epigallocatechin gallate was identified as the dominant component in the extract as determined by spectroscopy, and it was established that its oxidation was a function of the solution pH. Transmission electron microscopy, dynamic light scattering, and visible absorption spectroscopy (UV‐Vis) confirmed the reduction in silver ions to silver nanoparticles (Ag NPs). Controlling over Ag NPs shape and narrow size distribution was achieved with 10 ml green tea leaf extract solution and in different reaction pH. Spherical colloidal Ag NPs with well‐defined hydrodynamic diameters (with average hydrodynamic size of 27.9–50.2 nm) were produced. Silver nitrate concentrations used in this study were lower than that of reported in similar works, and synthesis efficiency was also higher. Nanoparticles were perfectly spherical and their uniformity, compared to similar studies, was much higher. These NPs showed higher degree of stability and were aqueously stable for >10 months in dark glasses at 4°C. [ABSTRACT FROM AUTHOR]

Abstract Silver is used in different applications that result in contact with skin and mucosal surfaces (e.g., jewelry, wound dressings, or eye drops). Intact skin poses an effective barrier against the absorption of silver. Mucosal surfaces are observed to be less effective barriers and compromised skin is often a poor barrier. Silver can deposit as particles in the human body causing a blue-gray discoloration known as argyria. Urine and feces are reported pathways of excretion. Acute human mortality has been observed following an abortion procedure involving the intrauterine administration of 7 g silver nitrate (64 mg silver/kg body weight). Localized argyria has been reported with exposure to silver ions, metallic surfaces, and nanocrystalline silver. Generalized argyria was observed with ionic and nanocrystalline silver in humans at cumulative doses in the range of 70–1500 mg silver/kg body weight. Silver is observed to have a low potential for skin irritation. Eye irritation and some cases of allergic contact dermatitis have been reported. Silver may cause genotoxicity, but additional data are required to assess its carcinogenic potential. Other reported toxicities include hepatic, renal, neurological, and hematological effects. Highlights • Silver is an ingredient in certain dermal and mucosal medical applications. • Silver can deposit in the body as particles causing a discoloration called argyria. • Silver seems to have a low potential for skin irritation. Eye irritation and allergic contact dermatitis have been reported. • Silver may cause genotoxicity, but additional data on its carcinogenic potential are required. [ABSTRACT FROM AUTHOR]