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[Display omitted] Novel two-dimensional MXene with unique optical and electrical properties has become a new focus in the field of sensing. In particular, their metallic conductivity, good biocompatibility and high anchoring ability to biomaterials make them attractive candidates. Despite such remarkable properties, there are certain limitations, such as low oxidative stability. MXene-Metal interactions are an effective strategy to maintain the long-term stability of MXene, while also improving the electrochemical activity and optical properties. Herein, a series of MXene/Ag nanocomposites including Ti 3 C 2 /Ag, Nb 2 C/Ag and V 2 C/Ag were designed based on the surface chemistry characteristics of MXene, where MXene served as the substrate for in-situ growth of silver nanoparticles via self-reduction of Ag(NH 3) 2 +. The results showed that V 2 C MXene has the strongest self-reducing ability due to its multiple variable valence states, larger interlayer space and more reactive groups. Moreover, V 2 C/Ag exhibited unexpected oxygen reduction reaction catalytic activity and photothermal performance. In view of which, an electrochemiluminescence-photothermal (ECL-photothermal) immunosensor was developed using V 2 C/Ag as ECL anchor and photothermal reagent for ultrasensitive detection of Lipolysis stimulated lipoprotein receptor. This work not only provides a simple and effective synthesis method of MXene supported metal nanocomposites, but also provides more inspirations for exploring the efficient biosensing strategies. [ABSTRACT FROM AUTHOR]

[Display omitted] Plasmon-mediated chemical reaction (PMCR) is a highly attractive field of research. Here we report in situ surface-enhanced Raman spectroscopic (SERS) monitoring of plasmonic-mediated S S bond-forming reaction. The reaction is thought to be a self-coupling reaction proceeding by photoinduced aromatic S C bond arylation. Surprisingly, the S C arylation and S S coupling are found to be occurred on both partially oxidized silver and silver nanoparticles. The results demonstrated that silver oxide or hydroxide and small molecule donor sacrifice agent played a crucial role in the reaction. This work facilitates the in-situ manipulation and characterization of the active silver electrode interface in conjunction with electrochemistry, and also establishes a promising new guideline for surface plasmon resonance photocatalytic reactions on metal nanostructures with high efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] Efficient utilizing CO 2 is crucial approaches in achieving carbon neutralization. One of the challenges lies in the in-situ conversion of low concentration CO 2 found in waste gases. This study introduces a novel heterogeneous catalyst known as silver nanoparticles in porous N -heterocyclic carbene polymer (Ag@POP-NL-3). The catalyst is synthesized via a streamlined pre-coordination method. Ag@POP-NL-3 exhibits uniform distribution of silver nanoparticles, a porous structure and nitrogen activation groups. It demonstrates high efficiency and selectivity in absorbing and activating CO 2 and enabling the conversion of low concentration CO 2 (30 vol%) from lime kiln waste gas into cyclic carbonate under mild conditions. This catalytic system achieves both CO 2 capture and resource utilization of CO 2 simultaneously, effectively fixing low-concentration CO 2 from waste gases into C 2+ valuable chemicals. This approach elegantly addresses two goals in one solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanocomposites of ZIF-8, carbon nanodots and silver nanoparticles are prepared. • A novel fluorescent sensing strategy is developed for the detection of H 2 O 2 and glucose based on AgNP-CD-ZIF-8. • Excellent analytical performances are achieved, which might inspire future studies on MOF assembly. In this study, a novel fluorescent biosensor is developed for the detection of H 2 O 2 and glucose based on Zeolitic Imidazolate Framework-8 (ZIF-8) nanocomposites. ZIF-8 encapsulating carbon nanodot (CD) exhibits bright fluorescence emission. After further loading of AgNP, the fluorescence is quenched, which is mainly based on the excited electron transfer from CD to AgNP. Besides, the excitation wavelength of CD falls within the adsorption range of AgNP, which leads to efficient inhibition of the excitation energy. The as-prepared AgNP-CD-ZIF-8 nanocomposites can be utilized as a highly sensitive platform for the analysis of H 2 O 2 and glucose. In the presence of glucose, H 2 O 2 can be generated by the catalysis of glucose oxidase (GOD), which induces the etching of AgNP and subsequent recovery of CD-ZIF-8 fluorescence. This "turn on" biosensor can be applied for facile and convenient quantification of H 2 O 2. It can also be further extended to detect glucose in real samples after combining specific catalytic effect of GOD. The analytical performances are excellent, which demonstrates great potential for practical utility. [ABSTRACT FROM AUTHOR]

Nanostructured titanium substrates provide inherent antimicrobial activity against drug-resistant fungi and bacteria, mimicking structures on the surface of naturally antimicrobial organisms. The addition of silver nanoparticles onto the nanostructures provides a secondary chemical antimicrobial mechanism and increases the efficacy in the response for both microbial species via low concentrations of silver. [Display omitted] Titanium and its alloys are commonly used implant materials. Once inserted into the body, the interface of the biomaterials is the most likely site for the development of implant-associated infections. Imparting the titanium substrate with high-aspect-ratio nanostructures, which can be uniformly achieved using hydrothermal etching, enables a mechanical contact-killing (mechanoresponsive) mechanism of bacterial and fungal cells. Interaction between cells and the surface shows cellular inactivation via a physical mechanism meaning that careful engineering of the interface is needed to optimse the technology. This mechanism of action is only effective towards surface adsorbed microbes, thus any cells not directly in contact with the substrate will survive and limit the antimicrobial efficacy of the titanium nanostructures. Therefore, we propose that a dual-action mechanoresponsive and chemical–surface approach must be utilised to improve antimicrobial activity. The addition of antimicrobial silver nanoparticles will provide a secondary, chemical mechanism to escalate the microbial response in tandem with the physical puncture of the cells. Hydrothermal etching is used as a facile method to impart variant nanostrucutres on the titanium substrate to increase the antimicrobial response. Increasing concentrations (0.25 M, 0.50 M, 1.0 M, 2.0 M) of sodium hydroxide etching solution were used to provide differing degrees of nanostructured morphology on the surface after 3 h of heating at 150 °C. This produced titanium nanospikes, nanoblades, and nanowires, respectively, as a function of etchant concentration. These substrates then provided an interface for the deposition of silver nanoparticles via a reduction pathway. Methicillin-resistant Staphylococcous aureus (MRSA) and Candida auris (C. auris) were used as model bacteria and fungi, respectively, to test the effectiveness of the nanostructured titanium with and without silver nanoparticles, and the bio-interactions at the interface. The presence of nanostructure increased the bactericidal response of titanium against MRSA from ∼ 10 % on commercially pure titanium to a maximum of ∼ 60 % and increased the fungicidal response from ∼ 10 % to ∼ 70 % in C. auris. Introducing silver nanoparticles increased the microbiocidal response to ∼ 99 % towards both bacteria and fungi. Importantly, this study highlights that nanostructure alone is not sufficient to develop a highly antimicrobial titanium substrate. A dual-action, physical and chemical antimicrobial approach is better suited to produce highly effective antibacterial and antifungal surface technologies. [ABSTRACT FROM AUTHOR]

Nanostructured titanium substrates provide inherent antimicrobial activity against drug-resistant fungi and bacteria, mimicking structures on the surface of naturally antimicrobial organisms. The addition of silver nanoparticles onto the nanostructures provides a secondary chemical antimicrobial mechanism and increases the efficacy in the response for both microbial species via low concentrations of silver. [Display omitted] Titanium and its alloys are commonly used implant materials. Once inserted into the body, the interface of the biomaterials is the most likely site for the development of implant-associated infections. Imparting the titanium substrate with high-aspect-ratio nanostructures, which can be uniformly achieved using hydrothermal etching, enables a mechanical contact-killing (mechanoresponsive) mechanism of bacterial and fungal cells. Interaction between cells and the surface shows cellular inactivation via a physical mechanism meaning that careful engineering of the interface is needed to optimse the technology. This mechanism of action is only effective towards surface adsorbed microbes, thus any cells not directly in contact with the substrate will survive and limit the antimicrobial efficacy of the titanium nanostructures. Therefore, we propose that a dual-action mechanoresponsive and chemical–surface approach must be utilised to improve antimicrobial activity. The addition of antimicrobial silver nanoparticles will provide a secondary, chemical mechanism to escalate the microbial response in tandem with the physical puncture of the cells. Hydrothermal etching is used as a facile method to impart variant nanostrucutres on the titanium substrate to increase the antimicrobial response. Increasing concentrations (0.25 M, 0.50 M, 1.0 M, 2.0 M) of sodium hydroxide etching solution were used to provide differing degrees of nanostructured morphology on the surface after 3 h of heating at 150 °C. This produced titanium nanospikes, nanoblades, and nanowires, respectively, as a function of etchant concentration. These substrates then provided an interface for the deposition of silver nanoparticles via a reduction pathway. Methicillin-resistant Staphylococcous aureus (MRSA) and Candida auris (C. auris) were used as model bacteria and fungi, respectively, to test the effectiveness of the nanostructured titanium with and without silver nanoparticles, and the bio-interactions at the interface. The presence of nanostructure increased the bactericidal response of titanium against MRSA from ∼ 10 % on commercially pure titanium to a maximum of ∼ 60 % and increased the fungicidal response from ∼ 10 % to ∼ 70 % in C. auris. Introducing silver nanoparticles increased the microbiocidal response to ∼ 99 % towards both bacteria and fungi. Importantly, this study highlights that nanostructure alone is not sufficient to develop a highly antimicrobial titanium substrate. A dual-action, physical and chemical antimicrobial approach is better suited to produce highly effective antibacterial and antifungal surface technologies. [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]

A complex nanostructure composed of silver nanocrystals randomly immobilized carbon nanoparticles randomly immobilized carbon nanoparticles was in situ synthesized by one-step solvothermal method using Toluene as carbon sources. [Display omitted] Silver nanoparticles (Ag NPs) have attracted extensive research interest in bioimaging and biosensing due to their unique surface plasmon resonance. However, the potential aggregation and security anxiety of Ag NPs hinder their further application in biomedical field due to their high surface energy and the possible ionization. Here, binary heterogeneous nanocomplexes constructed from silver nanoparticles and carbon nanomaterials (termed as C-Ag NPs) were reported. The C-Ag NPs with multiple yolk structure were synthesized via a one-step solvothermal route using toluene as carbon precursor and dispersant. The hydrophilic functional groups on the carbon layer endowed the C-Ag NPs excellent chemical stability and water-dispersity. Results showed that C-Ag NPs demonstrated excellent safety profile and excellent biocompatibility, which could be used as an intracellular imaging agent. Moreover, the C-Ag NPs responded specifically to hydroxyl radicals and were expected to serve as a flexible sensor to efficiently detect diseases related to the expression of hydroxyl radicals in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] Metallic nanoparticles of various shapes and sizes can be synthesised through a diversity of bottom-up pathways, such as precipitation induced by chemical reduction. Varying composition, by adjusting concentrations or adding/replacing species, is the predominant strategy to tune nanoparticles structures. However, controlling time down to the onset of precipitation, nucleation, should also provide a powerful means to control nanostructuration. We perform sequential reagent additions with a time resolution down to the millisecond. We use a millifluidic continuous flow setup consisting of tangential mixers in series, which allows flow rates up to dozens of litres per hour. We systematically vary both addition order and delay for each reagent involved in the synthesis of silver nanoplates. The resulting dispersions are compared using UV–visible spectroscopy, transmission electron microscopy and small-angle X-ray scattering. We show that synthesis pathways differing only in the order of sub-second additions lead to drastically different synthetic outcomes. Silver nanoparticles of different shapes and sizes, displaying an array of plasmonic colours, are synthesised at the same final composition by tuning the composition pathways along time. Our results unlock a previously inaccessible portion of the space of parameters, which will lead to an enhanced structural diversity, control and understanding of nanoparticles syntheses. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metallic silver clusters were the active sites for NO oxidation to yield nitrates. • The reduction of silver nitrates was the rate-determining step. • H 2 dissociated on the metallic silver clusters with a moderate energy barrier. • NO x reduction was dependent on silver loading, H 2 concentration, and reaction temperature. The role of silver species in the H 2 -assisted NH 3 selective catalytic reduction of NO x (H 2 -NH 3 -SCR) over Ag/Al 2 O 3 catalysts was investigated by operando spectroscopy (DRIFTS-MS and DR-UV–Vis) and Density Functional Theory (DFT) calculation. UV–Vis analysis showed that several kinds of silver species were present on the Ag/Al 2 O 3 , including dispersed silver cations, partially oxidized silver clusters, metallic silver clusters, and silver nanoparticles. Operando DRIFTS-MS experiments showed that the reduction of NO x was dependent on the formation rate of nitrates, which was closely related to the silver content, H 2 concentration, and reaction temperature. Notably, operando DR-UV–Vis experiments unambiguously confirmed that the metallic silver clusters were the active sites for nitrates formation, and the reduction of silver nitrates was much slower than NO oxidation. DFT calculations further revealed that reducing silver nitrates required higher energy barriers than NO oxidation, while H 2 dissociation could occur on metallic silver clusters with a moderate energy barrier. In conclusion, metallic silver clusters contributed to the formation of nitrates and H 2 dissociation, and the reduction of silver nitrates was the rate-determining step in the overall H 2 -NH 3 -SCR reaction. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are widespread in the environment due to the increase in their application e.g. in medicine as part of hard-to-heal wound dressings. Many studies have revealed easy diffusion of AgNPs into deep skin layers through damaged epidermis and contact with e.g. fibroblasts. Therefore, the aim of this study was to evaluate the impact of small-size AgNPs (10 nm) in ppm concentrations on the adipogenesis process in mouse embryo fibroblasts (3T3-L1). The results showed a decrease in the metabolic activity, followed by an increase in the reactive oxygen species (ROS) level in a dose- and time-dependent manner (0–20 ppm). The increased caspase-3 activity was observed only at the highest concentration (20 ppm) of AgNPs. Further analysis showed the ability of the tested NPs to increase the lipid accumulation in adipocytes, similar to ROSI [peroxisome proliferator-activated receptor gamma (PPARγ) agonist], measured by Oil-Red-O staining. Moreover, the analyses evidenced the ability of AgNPs to increase the lipoxygenase activity and malondialdehyde levels, which is probably based on ROS-dependent enhancement of lipid hydroperoxidation. Lastly, a significant increase in the PPARγ, Adiponectin, Resistin, Vegf , and Serpine mRNA expression was shown 6 h after the induction of the differentiation process. Based on the obtained results, it can be concluded that small-size AgNPs increase adipogenesis via ROS- and PPARγ-based mechanisms with potential engagement of crosstalk with the aryl hydrocarbon receptor, which is important due to the widespread application of AgNPs in medicine. However, more studies are needed to elucidate the full mechanism of these NPs in the tested cell model in depth. [Display omitted] • AgNPs cause increased accumulation of lipids during adipogenesis. • Lipoxygenase activity and malondialdehyde levels are significantly increased during adipogenesis. • The increase in the SFA content induced by AgNPs and ROS is a trigger factor of PPARγ. • AgNPs induce a characteristic mRNA expression pattern during adipogenesis in 3T3-L1. [ABSTRACT FROM AUTHOR]

Three step synthesis route to forming silver coated silica nanoparticles with citrate as a key ingredient to achieving morphological control. We describe the use of citrate to control the electroless plating of silver metal on silica nanoparticles. We find that the incorporation of relatively small amounts of citrate during the reduction of the Tollens' reagent in the presence of sensitized silica nanoparticles induces a continuous transition from conformal to raspberry particle coatings. This transition is dependent on both the citrate concentration and the silver precursor concentration. We characterize this transition using electron microscopy and spectroscopy and use these results to confirm citrate's ability to cap and restrict silver growth. We compliment these structural measurements with in-situ quartz crystal microbalance experiments to quantify citrate's role as a complexing agent to slow silver reduction kinetics. These results confirm citrate's dual role in controlling the morphology of silver deposits produced in this work. [ABSTRACT FROM AUTHOR]

Silver supported on lab-made CeO 2 nanoparticles (NPs) was an efficient catalyst for formaldehyde removal at low temperature. The hydroxyl groups on lab-made CeO 2 NPs stabilized HCHO molecules, and the large surface area of small Ag particles promoted the oxidation activity by readily adsorbing oxygen molecules and generating surface-active oxygen species. • Ag/CeO 2 with proper pretreatment exhibits high catalytic activity in HCHO removal. • Ag/CeO 2 calcined at 573 K and then reduced at 473 K exhibits the highest catalytic activity. • Nearly 100% conversion of 400 ppm HCHO is achieved at 333 K at high space velocity. • Surface hydroxyl groups on lab-made CeO 2 is favorable in stabilizing adsorbed HCHO molecules. • Small Ag particles readily adsorbing oxygen and generating surface-active oxygen species. Silver supported on CeO 2 nanoparticles (Ag/CeO 2) was found to be an efficient catalyst for formaldehyde removal at low temperature. The activity of Ag/CeO 2 catalysts in HCHO oxidation was markedly influenced by pretreatment at different calcination temperatures and H 2 reduction. A 6 wt%Ag/CeO 2 catalyst calcined at 573 K and then reduced at 473 K with 10% H 2 /N 2 showed 100% conversion of 400 ppm formaldehyde at 333 K with high gas hourly space velocity (GHSV = 24,400 h−1). The catalysts were characterized by various techniques, including N 2 adsorption–desorption, inductively coupled plasma mass spectrometry, X-ray diffraction, X-ray absorption near-edge structures, X-ray photoelectron spectroscopy, scanning transmission electron microscopy/energy dispersive spectroscopy, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy, temperature-programmed reduction with hydrogen, and in situ diffuse reflectance infrared Fourier transform spectrometry. The catalytic activity was correlated with the oxidation state and particle size of silver. Metallic Ag particles well dispersed on CeO 2 NPs could adsorb oxygen readily and generate surface-active oxygen species, which contributed to the oxidation of HCHO at low temperatures. The retention of surface hydroxyl groups on the surfaces of CeO 2 NPs also promoted catalytic performance for HCHO oxidation, probably by stabilizing the adsorbed HCHO molecules and removing protons from surface intermediates. [ABSTRACT FROM AUTHOR]

Ultrasmall silver nanoclusters (Ag NCs) are one of the emerging and highly efficient antibacterial agents, owing to the unique features of sub-2 nm particle size and the high abundance of the active Ag+ species. However, practical applications of Ag NCs in biological environment are often hampered by silver oxidization, which results in particle aggregation and loss of antibacterial activity. In this study, for the first time, we develop a facile method to synthesize highly dispersed Ag NCs decorated mesoporous silica nanoparticles (Ag NC-MSNs) capable of long-term and efficient release of Ag+ ions. This novel Ag NC-MSNs nanocomposite was demonstrated as an effective antibacterial agent against both Gram-positive and Gram-negative pathogenic bacteria. Compared with the counterparts Ag NCs and silver nanoparticles decorated mesoporous silica nanoparticles (Ag NP-MSNs), Ag NC-MSNs exhibit 17-fold and 27-fold enhancement in antibacterial potency, respectively. The homogeneous distribution of ultrasmall Ag NCs in the mesoporous architecture of supporting MSNs matrix is crucial for the controlled release of Ag+ ions, leading to the superior broad-spectrum antimicrobial activity. Moreover, the cytotoxicity assay indicated that the effective antibacterial concentration of Ag NC-MSNs shows minimum toxicity on mammalian cells. This new Ag nanocomposite developed in this work is promising for practical applications against various microbial infections. [ABSTRACT FROM AUTHOR]

This work deals with the removal of arsenic by nanoadsorbent from aqueous environment that is subsequently applied to the biological system for the evaluation of its efficiency. We started our aspiration by the modification of carboxylate functionalized silver nanoparticle (nanoadsorbent) fabrication process. Batch mode arsenic uptake study by the nanoadsorbent was conducted considering several altering parameters and the reactants in addition to products were evaluated by several analytical techniques for the interpretation of the interaction mechanism. It was found nanoadsorbent, Ag@MSA is an efficient system for the exclusion of arsenic (III) from the aqueous system and due to the alteration in the ratio of silver content and protective agent, the characteristic profile of silver nanoparticles with an average diameter of 15 nm also became changed in respect of reported results. Here the low pH range (4–6) favors the interaction between nanoparticle and arsenic and it was found that the interaction was chemical in nature through adsorption or complex formation with surface carboxylate groups of the protecting agent (MSA). Following the interaction, a successful removal of arsenic (III) was achieved at a percentage of 94.16 with an initial concentration of 45 mg/L and equilibrium time of 60 min. Hence nanoparticles were executed against the toxic effect of arsenic in E. coli, an important gut microbe of higher animals, for the restoration of bacterial growth in arsenic pre-removed media. In this context the validation of this removal efficiency against arsenic induced toxicity was proved through several morphological studies, degree of oxidative damages and other biochemical attributes. Image 1 • Carboxylate functionalized silver nanoparticle. • Interaction between Ag@MSA-arsenic in aqueous environment. • Arsenic (III) removal by monolayer protected silver nanoadsorbent. • Oxidative damages due to arsenic (III) exposure. [ABSTRACT FROM AUTHOR]

In this study, we synthesized silver nanoparticle-loaded cashew nut shell activated carbon (Ag/CNSAC). The synthesized samples were characterized by XRD, XPS, SEM with EDS, FT-IR, and BET analysis. The XRD, XPS, and EDS data provided convincing proof that Ag loaded on CNSAC is formed. The energy dispersive spectrum analysis and X-ray diffraction pattern both supported the face-centered cubic and amorphous structures of Ag/CNSAC. The SEM micrographs showed the inner surface development of Ag NPs and many tiny pores in CNSAC. The photodegradation of methylene blue (MB) dye by the Ag/CNSAC photocatalyst was investigated. This effective degradation of MB dye by Ag/CNSAC is attributed to the cooperative action of Ag as a photocatalyst and CNSAC as a catalytic support and adsorbent. In tests with gram-positive and negative bacteria including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) , the as-synthesized Ag/CNSAC showed outstanding antibacterial efficiency. Additionally, this study demonstrates a workable procedure for creating an affordable and efficient Ag/CNSAC for the photocatalytic eradication of organic contaminants. • Silver loaded cashew nut shell activated carbon (Ag/CNSAC) was synthesized from waste cashew nut shell. • The specific surface area of Ag/CNSAC was determined as 271.5 m2/g by BET analysis. • The photodegradation efficiency of Ag/CNSAC is improved (98.3%) compared to the CNSAC sample. • The produced Ag/CNSAC showed antibacterial activity against both of E. coli and S. aureus bacteria. [ABSTRACT FROM AUTHOR]

The alarming impact of antibiotic resistance sparked the quest for complementary treatments to overcome the confrontation over resistant pathogens. Metallic nanoparticles, especially silver nanoparticles (Ag NPs) have gained a much attention because of their remarkable biological characteristics. Moreover, their medicinal properties can be enhanced by preparing the composites with other materials. This article delves a comprehensive review of biosynthesis route for Ag NPs and their nanocomposites (NCs) with in-depth mechanism, methods and favorable experimental parameters. Comprehensive biological features Ag NPs such as antibacterial, antiviral, antifungal have been examined, with a focus on their potential uses in biomedicine and diagnostics has also been discussed. Additionally, we have also explored the hitches and potential outcomes of biosynthesis of Ag NPs in biomedical filed. [Display omitted] • Delves a comprehensive review of biosynthesis route for Ag NPs and their nanocomposites (NCs) with in-depth mechanism. • Various biological applications such as antibacterial, antiviral, antifungal, anticancer has been discussed. • Explored potential challenges and outcomes of biosynthesis of Ag NPs in biomedical filed. [ABSTRACT FROM AUTHOR]

Nanomaterials have been produced with the use of bio-nanotechnology, which is a low-cost approach. Currently, research is being conducted to determine whether actinomycetes isolated from Egyptian soil can biosynthesize Ag nanoparticles (Ag NPs) and characterized by using the following techniques: Transmission electron microscopy (TEM), Dynamic light scattering (DLS), Fourier transforms infrared (FT-IR), Energy-dispersive X-ray spectroscopy (EDX), UV–Vis spectroscopy and X-ray diffraction (XRD). The most promising actinomycetes isolate were identified, morphologically, biochemically, and molecularly. Streptomyces avermitilis Azhar A.4 was found to be able to reduce silver metal nanoparticles from silver nitrate in nine isolates collected from Egyptian soil. Toxicity of biosynthesized against 2nd and 4th larval instar of Agrotis ipsilon (Hufn.) (Lepidoptera: Noctuidae) was estimated. In addition, activity of certain vital antioxidant and detoxifying enzymes as well as midgut histology of treated larvae were also investigated. The results showed appositive correlations between larval mortality percentage (y) and bio-AgNPs concentrations (x) with excellent (R2). The 4th larval instar was more susceptible than 2nd larval instar with LC 50 (with 95% confirmed limits) =8.61 (2.76–13.89) and 26.44(13.25–35.58) ppml−1, respectively of 5 days from treatment. The initial stages of biosynthesized AgNps exposure showed significant increases in carboxylesterase (CarE) and peroxidases (PODs) activity followed by significant suppression after 5 days pos-exposure. While protease activity was significantly decreased by increasing time post-exposure. Midgut histology showed abnormality and progressive damage by increasing time post exposure leading to complete destruction of midgut cells after 5 days from exposure. These results make biosynthesized AgNPs an appropriate alternative to chemical insecticide in A. ipsilon management. [Display omitted] • Isolation and identification of actinomycetes strain from soil samples and examination their potential as biosynthesis. • Study the toxicity impact of Ag nanoparticles on the black cutworm A. ipsilon larvae. • Determination of physiological changes in some antioxidant and detoxification enzymes of black cutworm A. ipsilon. • Finally, investigation of the changes in midgut histology of the black cutworm after its exposure to Ag nanoparticles. [ABSTRACT FROM AUTHOR]

The current investigation aimed at bimetallic gold-silver nanoparticles (Au/Ag NPs), here called BM-GS NPs, synthesis using sericin protein as the reducing agent in an easy, cost-effective, and sustainable way. The obtained BM-GS NPs were characterized by UV–Visible spectroscopy, Transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS), atomic force microscopy (AFM), Dynamic light scattering (DLS) and Zeta potential, X-ray Powder Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and Thermogravimetric analysis followed by evaluation of its multitherapeutic and photocatalytic degradation potentials. The TEM analysis revealed its spherical nature and the EDS result displayed the presence of both Ag and Au elements, confirming the synthesis of BM-GS NPs. The XRD pattern verified the crystalline nature of the nanoparticles (NPs). The DLS analysis showed an average size of 86.08 d nm and the zeta potential showed a highly negative value (−26.3 mV) which specifies that the generated bimetallic NPs are stable. The BM-GS NPs exhibited positive wound healing potential (with 63.38% of wound closure rate at 25 μg/ml, as compared to 54.42% by the untreated control) with very negligible toxicity effect on the cell viability of the normal keratinocyte cells. It also demonstrated promising antioxidant properties with 65.00%, 69.23%, and 63.03% activity at 100 μg/ml concentration for ABTS (2, 2-azinobis) (3-ethylbenzothiazoline-6-sulfonic acid)), DPPH (1, 1 diphenyl-2-picrylhydrazyl) and SOD (superoxide dismutase enzyme) assays respectively, antidiabetic potential (with a significantly high α-glucosidase inhibition potential of 99.69% at 10μg/ml concentration and 62.11% of α-amylase enzyme inhibition at 100 μg/ml concentration) and moderate tyrosinase inhibitory potential (with 17.09% at 100 μg/ml concentration). Besides, it displayed reasonable antibacterial potential with the diameter of zone of inhibition ranging between 10.89 and 12.39 mm. Further, its antibacterial mode of action reveals that its effects could be due to being very smaller, the NPs could have penetrated inside the cellular membrane thereby causing rupture and damage to the interior materials leading to cellular lysis. The photocatalytic evaluation showed that synthesized BM-GS NPs have the efficiency of degrading methylene blue dye by 34.70% within 3 h of treatment. The above findings revealed the multi-therapeutic efficacy of the sericin globular protein-mediated BM-GS NPs and its potential future applications in the cosmetics and food sector and environmental contamination management industries. • Synthesis of sericin protein mediated bimetallic gold/silver nanoparticles (BM-GS NPs). • Structural and functional characterization of the BM-GS NPs. • The size of BM-GS NPs was found out to be 86.08 d nm and Zeta potential is −26.3 mV. • Displayed wound healing, tyrosinase inhibitory, antioxidant, antidiabetic & antibacterial potential. • Showed promising photocatalytic degradation of methylene blue dye. [ABSTRACT FROM AUTHOR]

• Nonabsorbable silk sutures were impregnated with biosynthesized silver nanoparticles. • Biogenic silver nanoparticle coated sutures exhibited potential antimicrobial activity against common pathogenic strain. • Biogenic silver nanoparticle coated sutures did not significantly effected the cell viability of NIH-3T3 fibroblasts. • Coating the sutures with green nanotechnology may help to fight against surgical site infections. Surgical sutures play important role during the wound healing of the surgical sites which are known to be sensitive to microbial infections. Silver nanoparticles (AgNPs) have been recently used as promising agents against multiple-drug resistant microorganisms. This study was designed to coat the sutures with silver nanoparticles obtained via a green synthesis approach. Microbial-mediated biological synthesis of AgNPs were carried out ecofriendly using Streptomyces sp. AU2 cell-free extract and deposited on silk sutures through an in situ process. Sutures coated with biosyntehsized AgNP (bio-AgNP coated sutures) were characterized using Scanning Electron Microscopy (SEM) and elemantal analysis were carried out using Energy Dispersive X-ray Spectroscopy (EDS). The silver amount released by the bio-AgNP coated sutures was calculated by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) throughout a degradation process. Antimicrobial potential of the bio-AgNP coated sutures was determined against common pathogenic microorganisms Candida albicans , Escherichia coli and Staphylococcus aureus. To determine the biocompatibility/cytotoxicty of the bio-AgNP coated sutures, the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) assay was used through an indirect test method; that the elutions obtained by the extraction of the sutures at 1, 4, 8 and 10. days and were placed in contact with 3T3 fibroblast cell culture. To best of our knowledge, this is the first report about coating of the nonabsorbable silk sutures with silver nanoparticles biosynthesized using a microbial extract. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • High-temperature annealing in air conferred CeO 2 nanorods abundant lattice oxygen. • O 3 activation enriched the active oxygen (O x −) on CeO 2 at cost of vacancy depletion. • CO oxidation relied crucially on the participation of pre-existing oxygen vacancies. • O x − (especially O 2 −) on CeO 2 affected the oxidation of soot and NO directly. • Aged CeO 2 nanorods impregnated with Ag exhibited superior oxidation activities. Abstract Though the catalytic oxidation of CO, NO and soot over CeO 2 could be understood within a similar Mars-van Krevelen-type mechanism, these reactions were likely to be driven by different active phases. In this work, several CeO 2 and Ag/CeO 2 nanorods with different contents of surface oxygen vacancies (V O-s) and active oxygen species (O x −) were designed as model catalysts. Their catalytic performance indicated that, CO oxidation was determined by pre-existing ceria V O-s , while O x − participated in NO and soot oxidation directly. Besides, by loading silver onto the high-temperature aged CeO 2 nanorods, Ag/CeO 2 catalysts with high availability of ceria lattice oxygen were obtained, whose low-temperature oxidation activity was proven comparable to that of the platinum catalysts. In this sense, the model designing in this work not only provided methods to find out proper reactivity descriptors, but also conferred low-cost catalysts with high practical potential. [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]

Durable Ag-Fe 3 O 4 /Fe superhydrophobic surface (SHS) with dendritic structures on the galvanic sheet was obtained by chemical etching, deposition and following annealing process. The promising SHS showed fine superhydrophobicity having the water contact angle of 165° and dynamic sliding angle of 2°. Experimental results showed that the obtained SHS sample has excellent properties of anti-corrosion, catalysis, anti-icing, rolling-off and self-cleaning. The conditions of etching, chemical immersion, and annealing to obtain SHS were investigated. Chemical stability and durability of SHS were investigated via storage in air for ten months. The SHS as a catalyst showed long-term stability, catalytic activity, and reusability, as compared to the substrate of the un-annealed surface. It is an effortless and cheap method to fabricate SHS on the galvanic sheet for industrial applications. The SHS has a potential utilization in a diverse range of bio-medicines, chemistry, microfluidics fields, and electronics. [ABSTRACT FROM AUTHOR]

In this study, we have prepared silver nanoparticles deposited cellulose microfibers (Ag-CMFs) with excellent catalytic property. The cellulose microfibers with a mean diameter of approximately 270 nm are regenerated by deacetylation of cellulose acetate microfibers. Silver nanoparticles are deposited onto the surface of the cellulose microfibers by a simple wet reduction of silver precursor using glucose as reducing agent. The morphology, thermal stability and catalytic activities of the samples have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and UV–vis spectrophotometer. The average size of Ag nanoparticles deposited on the fibers is approximately 10 ± 5 nm, and the deposition of the Ag nanoparticles does not change the morphology of the cellulose microfibers. The obtained Ag-CMFs exhibit excellent catalytic activity and reusable character for the reduction of p -nitrophenol by sodium borohydride. Therefore, the Ag-CMFs prepared by the facile method is expected to be an effective and promising catalytic material. [ABSTRACT FROM AUTHOR]

In an effort to verify a previous striking report that ethanol could be oxidized selectively to ethylene oxide, ethanol oxidation on Ag, Cu, or Au nanoparticles supported on Li 2 O/γ-Al 2 O 3 or γ-Al 2 O 3 was examined between 100 and 400 °C. Ag and Cu catalysts were found to be highly selective to acetaldehyde (>95% on Ag below 325 °C and on Cu below 250 °C). On Au, selectivities to acetaldehyde were lower, with higher selectivity to ethyl acetate and acetic acid. No ethylene oxide was observed under any conditions. Our results, including selectivity variations among these metals, are consistent with previous studies of ethanol oxidation over coinage metals supported on γ-Al 2 O 3 , with no changes in primary product identity and minor changes in selectivity upon addition of Li 2 O. Unfortunately, these results are in direct contradiction to previous work reporting the desirable direct conversion of ethanol to ethylene oxide on Ag, Cu, and Au on Li 2 O/γ-Al 2 O 3 . [ABSTRACT FROM AUTHOR]

Development of new functional coatings in the field of health care, as antibacterial applications, deals with a straight control of the diffusive properties that rules the releasing of the active component. In this work, the development of a silver-rich nanocomposite thin coating, loaded with organically modified clay nanoparticles, is presented. The synthesis process included an environment-friendly silanization process of clay nanoparticles (Laponite® S482) with (3-glycidoxypropyl)trimethoxysilane (GPTMS) and the further hydrolytic condensation with tetraethoxysilane (TEOS). Silanization process and the obtained coatings were analysed by Fourier transformed infrared spectroscopy, UV–visible spectroscopy, X-ray diffraction, thermogravimetric curves and scanning electron microscopy. The silanization process of clay nanoparticles with the organically reactive alkyl alkoxysilane, allowed to stabilize and exfoliate the clay nanosheets within a hybrid organic-inorganic sol-gel material. Ring opening of grafted epoxy groups carried to an increasing of the basal spacing, of intercalated clay nanosheets, from 1.3 to 1.8 nm. Moreover, incorporation of organically modified clay nanosheets introduced a significant stabilization on the development of silver nanoparticles inside the structure of the nanocomposite coating, retaining the silver inside the coating material and restricting the growing of silver nanoparticles on the surface of the coating. Antibacterial behaviour, against E . coli cultures, performed through agar diffusion tests, provided promising results that allow assuming that the studied nanocomposite coating serves as a reservoir of ionic silver, permitting the antibacterial effect. [ABSTRACT FROM AUTHOR]

Hypothesis Bimetallic nanoparticles made of iron oxide and Ag could be fabricated by pulsed laser ablation of iron and silver targets in pure water by a two-step route. These nanoparticles could exhibit both magnetic and plasmonic properties. Experiments Bimetallic nanoparticles were fabricated by using a focused Nd:YAG nanosecond laser source emitting a 1064 nm wavelength radiation and characterized with ζ-potential, Dynamic Light Scattering (DLS), UV–vis absorption, Transmission Electron Microscopy (TEM), High Resolution TEM (HRTEM), Energy Dispersive X-ray Spectrometry (EDX), and Selected Area Electron Diffraction (SAED). The magnetic character of the nanoparticles was ascertained by observing attraction by a magnet and complete removing from the water environment, while their SERS (surface-enhanced Raman scattering) response was checked by decorating them with 2,2′-bipyridine as molecular reporter and performing Raman tests with green (514.5 nm) and far-red (785 nm) excitation wavelengths. Findings The observed magnetic attraction was due to magnetite (Fe 3 O 4 ), the only ferromagnetic iron oxide form evidenced by the characterization tests in the aqueous colloidal system, where silver nanoparticles were also embedded. UV–vis and SERS spectra confirmed the presence of nanostructured silver as plasmonic constituent of the fabricated metal nanoparticles. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication of melamine sponge decorated with silver nanoparticles-modified graphene (G/AgNPs-MS) for water disinfection. The G/AgNPs-MS composites with the high porosity and elasticity were used in an antibacterial process in which the composite was first immersed in bacterial suspension, and subsequently squeezed via hand compression. G/AgNPs-MS exhibited more excellent bactericidal activity against Escherichia coli and Staphylococcus aureus bacteria compared with melamine sponge (MS), melamine sponge decorated with graphene (G-MS), and melamine sponge decorated with silver nanoparticles (AgNPs-MS). The superior antibacterial effect was possibly ascribed to the coordination of graphene oxide (GO) and silver nanoparticles (Ag NPs). Compared to AgNPs-MS, G/AgNPs-MS displayed better stability with fewer Ag + release. G/AgNPs-MS composites were highly reusable with no significant differences in the loss of bacterial viability over 12 operational cycles. The possible antibacterial mechanism of G/AgNPs-MS was also investigated. It was found that the destruction of bacterial membrane by G/AgNPs-MS played an important role in the bactericidal activity. The generation of intercellular ROS and scavenging assays confirmed the involvement of Ag + and ROS in the antibacterial process of G/AgNPs-MS. All the results demonstrated that the prepared G/AgNPs-MS composites, as innovative antibacterial materials, showed a great potential for water disinfection. [ABSTRACT FROM AUTHOR]

In this work, the efficiency of the ubiquitous fungus Penicillium sp. 8L2 to remove Ag(I) ions from synthetic solutions and its potential to synthesize silver nanoparticles (AgNPs) was evaluated. Using a Rotatable Central Composite Design pH and biomass concentration were optimized. Maximum biosorption capacity 51.53 mg/g, by Langmuir model, comparing favourably with other reports. The fungal biomass was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and analyzed before and after the biosorption process by different techniques: X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Ultra-High Resolution Transmission Electron Microscopy and Energy Dispersive X-ray (HR-TEM-EDX) and Ultraviolet–Visible Spectrophotometry (UV–vis). The results showed that the fungus applied several mechanisms to remove Ag(I) ions from the solution and that some of them induced the synthesis of AgNPs. This fact could be verified in the synthesis tests from the cell extract in which aqueous suspensions with high concentrations of AgNPs were obtained. These nanoparticles had diameters between 2 and 9 nm and therefore a high potential for their use as biocidal agents. The results indicated that the synthesis of nanoparticles could be an added value to the heavy metal biosorption process. • The ubiquitous fungus Penicillium sp. 8L2 is effective biosorbent for Ag(I). • Both the fungus and its cell extract are capable of synthesizing AgNPs as added value. • Nanoparticles are easily recovered and have very small sizes (<10 nm). • The recovered nanoparticles can be applied in other biotechnological areas. • FT-IR, UV–vis, XRD, TEM and FESEM-EDX techniques were used. [ABSTRACT FROM AUTHOR]

An electrostatically-assisted strategy for fabrication of thin film composite capacitors with controllable dielectric constant ( k ) has been developed. The capacitor is composed of metal–dielectric core/shell nanoparticle (silver/silica, Ag@SiO 2 ) multilayer films, and a backfilling polymer. Compared with the simple metal particle-polymer mixtures where the metal nanoparticles (NP) are randomly dispersed in the polymer matrix, the metal volume fraction in our capacitor was significantly increased, owing to the densely packed NP multilayers formed by the electrostatically assisted assembly process. Moreover, the insulating layer of silica shell provides a potential barrier that reduces the tunneling current between neighboring Ag cores, endowing the core/shell nanocomposites with a stable and relatively high dielectric constant ( k ) and low dielectric loss ( D ). Our work also shows that the thickness of the SiO 2 shell plays a dominant role in controlling the dielectric properties of the nanocomposites. Control over metal NP separation distance was realized not only by variation the shell thickness of the core/shell NPs but also by introducing a high k nanoparticle, barium strontium titanate (BST) of relatively smaller size (∼8 nm) compared to 80–160 nm of the core/shell Ag@SiO 2 NPs. The BST assemble between the Ag@SiO 2 and fill the void space between the closely packed core/shell NPs leading to significant enhancement of the dielectric constant. This electrostatically assisted assembly method is promising for generating multilayer films of a large variety of NPs over large areas at low cost. [ABSTRACT FROM AUTHOR]

We synthesized hollow core–satellite nanoassemblies comprised of hollow zinc sulfide (ZnS) shells decorated with silver nanoparticles (Ag NPs). This was achieved by solution-phase attachment of Ag NPs to hollow ZnS nanospheres (NSs) prepared by spray pyrolysis. This produces an aqueous dispersion of ZnS–Ag hybrid structures, 50–500 nm in overall diameter. We characterized the nanostructures by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX) to elucidate the ZnS (core)–Ag (satellite) morphology and optimize conditions for producing such structures. Optical spectroscopy showed that photoluminescence of ZnS was quenched by Ag while absorbance was enhanced. This work provides a simple and general means of producing hollow core–satellite structures that could be of broad applicability. [ABSTRACT FROM AUTHOR]

This study investigated the effects of dissolved organic matter (DOM) and various electrolytes commonly found in environmental aqueous matrices on the physicochemical properties and bactericidal efficacy of silver nanoparticles (AgNPs), which are immobilized on cryogels (or PSA/AgNP cryogel). The AgNPs in the PSA/AgNP cryogel that were exposed to different media underwent morphological transformation in terms of particle size and structure. In addition, the presence of DOM and electrolytes increased the release of dissolved Ag. The biological uptake of Ag species (determined as the total Ag in exposed cells) increased in the presence of DOM, but decreased in the presence of electrolytes. The presence of electrolytes did not result in any significant reduction in the bactericidal activity. Although an initial increase of the DOM to 2.5 mg-C L −1 attenuated the bactericidal efficacy of the immobilized AgNPs, an increase in the DOM concentration beyond 5 mg-C L −1 enhanced the bactericidal efficacy. This study found that the bactericidal activity of the immobilized AgNPs is less sensitive to the solution chemistry relative to the free AgNPs. This suggests that immobilizing the AgNPs in a supporting material is a good strategy to preserve their efficacy for disinfection in various aqueous matrices. [ABSTRACT FROM AUTHOR]

The common household material, egg shell of Anas platyrhynchos is utilized for the synthesis of Silver and Gold–Silver core shell nanoparticles using greener, environment friendly and economic way. The egg shell extracts were acting as a stabilizing and reducing agents. This method avoids the use of external reducing and stabilizing agents, templates and solvents. The effects of various reaction parameters, such as reaction temperature, concentration in the formation of nanoparticles have also been investigated. The compositional abundance of gelatin may be envisaged for the effective reductive as well as stabilizing potency. The mechanisms for the formation of NPs have also been presented. The synthesized Ag NPs formed were predominantly spherical in nature with an average size of particles in the range of 6–26 nm. While, Au–Ag core shell nanoparticles formed were spherical and oval shaped, within a narrow size spectrum of 9–18 nm. Both the Ag NPs Au-and Ag core shell nanoparticles showed characteristic Bragg’s reflection planes of fcc structure and surface plasmon resonance at 430 nm and 365 nm, respectively. The NPs were utilized for the removal of toxic and hazardous dyes, such as Rose Bengal, Methyl Violet 6 B and Methylene Blue from aqueous phase. Approximately 98.2%, 98.4% and 97% degradations of Rose Bengal, Methyl Violet 6 B, and Methylene Blue were observed with Ag NPs, while the percentage degradation of these dyes was 97.3%, 97.6% and 96% with Au–Ag NPs, respectively. Therefore, the present study has opened up an innovative way for synthesizing Ag NPs and Au–Ag bimetallic nanostructures of different morphologies and sizes involving the utilization of egg shell extract. The high efficiency of the NPs as photocatalysts has opened a promising application for the removal of hazardous dyes from the industrial effluents. [ABSTRACT FROM AUTHOR]

Films of silver nanoparticles have optical properties that are useful for applications such as plasmonic light trapping in solar cells. We report on the simple fabrication of Ag nanoparticle films via thermal evaporation, with and without subsequent annealing. These films result in a random array of particles of various shapes and sizes. The modeling of such a vast collection of particles is still beyond reach of the modern computers. We show that it is possible to represent the silver island films by the Bergman effective mediums with the same optical properties. The effective medium method provides us with deep insight about the shape, the size and the distribution of nanoparticles. The far field simulations of solar cells, in which the silver island film is replaced with an effective medium layer, show a reduction in the absorption of active layer. Besides, the near field simulations based on finite-difference time-domain technique demonstrate that the near field effects on active layer absorption are negligible and this method highlights the importance of nanoparticles shapes. The PCPDTBT:PCBM solar cells with embedded silver island films are fabricated, and it is found that their performances show the similar trend. This insight can be used for the optical analysis of thermally evaporated Ag nanoparticle films for the improvement of organic solar cells. [ABSTRACT FROM AUTHOR]

Microplastics are frequently detected in natural aquatic systems proximate to populated areas, such as urban rivers and lakes, and can be rapidly colonized by microbial communities. Microplastics and silver nanoparticles (AgNPs) share similar pathways into natural waters and tend to form heteroaggregations. However, very little is known about the long-term impacts on the structure and function of microplastic biofilms when chronically exposed to silver nanoparticles. Thus, the present study assessed the accumulation property of AgNPs on polymethyl methacrylate (PMMA) microplastics via adsorption tests and studied the chronic effects of AgNPs on the structure and function of microplastic biofilms via 30-day microcosmic experiments in eutrophic water. The adsorption tests showed that the biofilms-colonized PMMA microplastics presented the highest adsorption of 0.98 mg/g in the 1 mg/L AgNPs microcosms. After the 30-day exposure, lactic dehydrogenase release and reactive oxygen species generation of PMMA biofilms increased by 33.23% and 23.98% compared to the MPs-control group with no-AgNPs, indicating that the number of dead cells colonizing microplastics significantly increased. Network analysis suggested that the stabilization of the bacterial community declined with the long-term exposure to AgNPs through the reduction of the modularity and average path length of the network. Compared to the MPs-control group, long-term exposure to AgNPs caused cumulatively inhibitory effects on the nitrogen removal and the N 2 O emissions in eutrophic water. The isotopomer analysis revealed that the contribution rate of NO 2 − reduction to N 2 O emissions was gradually increasing with the AgNPs exposure. Real-time PCR analysis showed that denitrification genes were less sensitive to AgNPs than the nitrification genes, with gene nos Z performed the most negligible response. Overall, our results revealed that long-term exposure to AgNPs could alter biogeochemical cycling involved by microplastic biofilms and cumulatively reduce the self-recovery of the eutrophic ecosystem. [Display omitted] • Biofilms could facilitate AgNPs accumulation onto PMMA microplastics. • Stability of bacterial community structure on MPs reduced with the exposure of AgNPs. • AgNPs caused cumulatively inhibitory effects on nitrogen removal. • Nitrification genes on MPs were more sensitive to AgNPs than denitrification genes. • AgNPs increased contribution rate of NO2- reduction to N 2 O emissions on MP biofilm. [ABSTRACT FROM AUTHOR]

Hypothesis The reproducible surface enhanced Raman scattering (SERS)-based sensing of an analyte relies on high quality SERS substrates that offer uniformity over large areas. Uniform ZnO nanoarrays are expected to offer an appropriate platform for SERS sensing. Moreover, since ZnO has good photocatalytic properties, controllable decoration of silver nanoparticles on ZnO nanoarrays may offer an additional opportunity to clean up SERS substrates after each sensing event. Experiments This study employs a facile soft chemical synthesis strategy to fabricate Raman-active and recyclable ZnO/Ag nanorod arrays as reproducible SERS substrates. Arrays of ZnO nanorods were synthesized using hydrothermal method, which was followed by controllable decoration of ZnO with silver nanoparticles (AgNPs) using an electroless plating technique. Findings The uniform density of SERS-active ‘hot-spots’ on ZnO nanoarrays could be controlled on a large 1 × 1 cm 2 substrate. These ZnO/Ag nanoarrays showed high reproducibility (0.132 RSD) towards acquiring SERS spectra of rhodamine B (RB) at 30 random locations on a single substrate. The photocatalytic nature of ZnO/Ag semiconductor/metal hybrid endowed these substrates with reusability characteristics. By controlling metal loading on a semiconductor surface, photocatalytic activity and high SERS performance can be integrated within a single package to obtain high quality, reproducible, stable and recyclable SERS substrates. [ABSTRACT FROM AUTHOR]

In this study a synthetic approach for the stable, mono-dispersed high yielding bimetallic (Ag-Se) nanoparticles by quercetin and gallic acid is described. The bimetallic nanoparticles were synthesized at room temperature. Different reaction parameters (concentration of quercetin, gallic acid and Ag/Se salt, pH, temperature and reaction time) were optimized to control the properties of nanoparticles. The nanoparticles were characterized by various analytical techniques and their size was determined to be 30-35 nm. Our findings suggest that both the reduction as well as stabilization of nanoparticles were achieved by the flavonoids and phenolics. This study describes the efficacy of quercetin and gallic acid mediated synthesis of bimetallic (Ag-Se) nanoparticles and their in vitro antioxidant, antimicrobial (Gram-positive and Gram-negative bacteria) and antitumor potentials. The synthesized Ag-Se nanoparticles were used as anticancer agents for Dalton lymphoma (DL) cells and in in vitro 80% of its viability was reduced at 50 μg/mL. [ABSTRACT FROM AUTHOR]

The science world advancing day by day contributes to living systems in many areas with the development of nanotechnology. Besides being easily obtained from plants, the advantages it brings increase the importance of nanotechnology. Environmentally friendly, economical, and compatible with plants are just a few of the advantages it brings. Silver metal is one of the most preferred active ingredients in nanoparticle synthesis. Arum italicum is used in the treatment of various diseases in the health sector due to the structures it contains. In our study, nanoparticle synthesis was made by using Ag metal with Arum italicum plant. Then, the antimicrobial, DNA damage prevention and DPPH radical quenching activity of Ag NPs/Ai nanoparticles were investigated. The interaction of the plant with Ag, analysis by X-ray diffraction (XRD), UV visible spectrophotometer (UV–vis), scanning electron microscope and energy dispersive X-ray (SEM-EDX), Fourier-converted infrared spectroscopy (FT-IR) methods has been done. It has been observed that Ag NPs/Ai clusters formed by Arum italicum with Ag have an antibacterial effect against Bacillus subtilis, Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli pathogens. However, an antifungal effect hasn't been observed against Candida albicans fungus. Pseudomonas aeruginosa bacteria exerted a stronger effect than an antibiotic. It is seen that Ag NPs/Ai has a protective and anti-damage effect against DNA damage. The antioxidant effect of Ag NPs/Ai is remarkable when DPPH radical quenching activity is compared to positive control BHA and BHT. • Ag NPs/Ai's showed a stronger effect against Pseudomonas aeruginosa than the antibiotic. • It was observed that Ag NPs/Ai had an anti-damage effect on pBR322 plasmid DNA. • Ag NPs/Ai were found to have antioxidant properties (86.36% at 100 μg/ml). • It is thought that Ag NPs/Ai bioagents can be used in the treatment of cancer and bacterial diseases. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sol–gel ZnO:Ag films deposited by spin coating and annealed at 500–800°C range in nitrogen and oxygen ambients. [•] The formation of silver nanoparticles is proved by XRD study. [•] No silver oxide phases are traced by XRD and FTIR analyses. [•] ZnO:Ag films reveal plasmonic absorption features. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monodisperse PGMA particles carrying COOH or NH2 groups were developed. [•] Electrophoretic mobilities and ζ potential values of the particles were determined. [•] Poly(glycidyl methacrylate)/Ag nanocomposite microspheres were prepared. [•] The composite microspheres were used as efficient radioiodine scavenger. [Copyright &y& Elsevier]

Highlights: [•] We review the oral toxicity of ionic, nanoparticulate and colloidal silver. [•] Effects of silver formulations on different organ systems are described. [•] We report dose levels responsible for the effects. [•] We discuss whether effects of silver nanoparticles are mediated by released ions. [•] We report a Margin of Safety of at least 5 before a level of concern is reached. [Copyright &y& Elsevier]

Highlights: [•] Biosynthesis of silver nanoparticles (AgNPs). [•] Characterization on AgNPs using various techniques. [•] Plausible mechanism of silver nanoparticle synthesis. [•] Evaluation of AgNPs as antioxidant and anticancer agent. [Copyright &y& Elsevier]

The development of environmentally friendly new procedures for the synthesis of metallic nanoparticles is one of the main goals of nanotechnology. Proteins and enzymes from plants, filamentous fungi, yeast, and bacteria to produce nanoparticles are both valuable and viable alternatives to conventional synthesis of nanomaterials due to their high efficiency and the low cost to scale up and generate large quantities. The aim of this work is to compare biogenic silver nanoparticles (AgNPs) obtained from cell-free filtrates from the fungus Macrophomina phaseolina to conventional chemical AgNPs, in biocidal activity and toxicity. Our results show that bio-AgNPs displayed similar bactericidal activity than chemical AgNPs, but less toxicity in the model organism Caenorhabditis elegans. We employed biochemical and proteomic techniques to profile the unique surface chemistry of the capping in the bio-AgNPs and therefore to identify the proteins involved in their synthesis and stability. These results not only suggest that the proteins involved in the synthesis of the nanoparticles and corona formation in the bio-AgNPs are responsible for keeping the silver core preserved making them more stable in time, but also masking and protecting eukaryotic cells from metal toxicity. [Display omitted] • Bio-AgNPs presented similar bactericidal activity to conventional chemical AgNPs. • Most proteins involved in the bio-AgNPs synthesis process were oxidoreductases. • Secreted fungal proteins were part of the NPs corona architecture. • Protein corona kept the NP metallic core preserved, leading to higher stability. • Corona in bio-AgNPs masked the metal core, rendering low toxicity in eukaryotes. [ABSTRACT FROM AUTHOR]

Abstract: Titanium dioxide (TiO2) is a well-studied photocatalyst that is known to break down organic molecules upon ultraviolet (UV) irradiation. Cellulose nanofibers (CNFs) act as an attractive matrix material for the suspension of photocatalytic particles due to their desirable mechanical and optical properties. In this work, TiO2–CNF composite films were fabricated and evaluated for photocatalytic activity under UV light and their potential to remove organic compounds from water. Subsequently, gold (Au) and silver (Ag) nanoclusters were formed on the film surfaces using simple reduction techniques. Au and Ag doped TiO2 films showed a wider spectral range for photocatalysis and enhanced mechanical properties. Scanning electron microscopy imaging and energy dispersive X-ray spectroscopy mapping were used to evaluate changes in microstructure of the films and monitor the dispersion of the TiO2, Au, and Ag particles. The ability of the films to degrade methylene blue (a model organic dye) in simulated sunlight has been demonstrated using UV–visible spectroscopy. Reusability and mechanical integrity of the films were also investigated. [Copyright &y& Elsevier]

Abstract: Block copolymer (BCP) micelles formed by polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) were used as nanoreactors for preparing stable bimetallic AuAg nanoparticles (NPs) with finely tunable composition and diameters. Micelles loaded with NPs were then deposited onto TiO2 and Al2O3 in order to investigate the catalytic properties of the NPs with respect to CO oxidation. The polymer matrix could be removed by thermal treatment at 400°C under H2 or O2. Different parameters, such as support, particle size, and metal composition were varied independently, so that their influence on the catalytic activity for CO oxidation could be separated. The atomic Au/Ag ratio was varied from 1:2 to 2:1, and the highest activity was obtained for an Au/Ag ratio of 1, showing synergy effects of both metals for catalyzing CO oxidation. Using nanosized TiO2 as support and an Au/Ag ratio of 1, the nanoparticle diameter was varied between ∼3 and ∼20nm which led to a variation of activity by a factor of ∼7 (in a continuous flow reactor at 70°C) with the smallest particles showing the highest turnover frequencies (TOFs). In comparison, regular TiO2 as catalyst carrier showed significantly lower performance than nanostructured TiO2 while no activity was found on non-reducible γ-Al2O3. Independently, all three parameters (metal particle size, Au/Ag atomic ratio, and the support) showed significant effects on the catalytic activity. [Copyright &y& Elsevier]

Abstract: Chitosan, associated with cellulose fibers, can be used for elaborating sponge-like structures (membranes, foams) for the binding of silver ions. The composite material has very promising antibacterial properties versus Pseudomonas aeruginosa (Gram−)≫ Escherichia coli (Gram−)> Staphylococcus hominis (Gram+)≫ Staphylococcus aureus (Gram+). The amount of silver required for bactericidal effect is quite low (below 0.1mg per disk, this means less than 6mgAgg−1) in antibiogram-type test but also for the treatment of water suspensions (in dynamic mode with water recycling). The presence of cellulose fibers improves the efficiency of metal binding, due to chitosan dispersion and enhancement of the availability and accessibility of amine groups. Silver nanoparticles (about 100nm) were observed by scanning electron microscopy. The photo-reduction (exposure to sun light or UV lamp) leaded to the partial aggregation of silver nanoparticles: metal ions that were released tended to aggregate at the surface of the material. [Copyright &y& Elsevier]

Abstract: Cellulose fabrics were coated with polypyrrole–silver (PPy/Ag) nanocomposite films via one pot photopolymerization in aqueous media. This process was optimized for various concentrations of pyrrole/textile weight ratios with fixed molar ratio of [pyrrole]/[AgNO3] as 2.5. Simple weight measurements of the fabrics indicated progressive coating of PPy/Ag versus initial pyrrole/fabric weight ratio and photopolymerization time. X-ray diffraction (XRD) data confirm the nano-size (10–30nm) and metallic state of Ag crystallites. The metallic state of silver particles was also confirmed by X-ray photoelectron spectroscopy (XPS). We demonstrate that UV-induced polymerization of pyrrole in the presence of AgNO3 is simple and fast compared to chemical oxidative polymerization in the absence of UV light. More importantly, it permits to coat cellulose fabrics in one pot by polypyrrole/Ag nanocomposites films in environmentally friendly aqueous solutions at room temperature. [Copyright &y& Elsevier]

Abstract: Silver nano-shells (SNSs) were synthesized via a two-step seeds-mediated method. Polymer cores were composed of ultrafine gold nanoparticles (NPs) modified chitosan–poly(acrylic acid) nanoparticles (CS–PAA NPs). Then, deposition of silver upon gold nucleus leads to the seed enlargement and finally forms silver shell on the surface of CS–PAA NPs to get SNSs. Transmission electron microscope (TEM) showed SNSs had a discrete silver shell plus some pores and gaps, which could acted as “hot spots” and provided the great potential of these SNSs to be used as SERS substrates with wavelength ranging from visible to infrared region (700–1000nm) by tuning shell coverage of silver. SERS experiments with dibenzyl disulphide (DBDS) as the indicator showed that the resulting SNSs allowed the production of highly consistent enhancement of the Raman signals down to nM concentrations of DBDS. Considering the excellent biocompatibility of polymer core and their small size, these SNSs are highly desirable candidates as the enhancers for high performance SERS analysis and as SERS optical labels in biomedical imaging. [Copyright &y& Elsevier]

Abstract: In the present work, electrochemical anodization has been used to prepare uniform TiO2 nanotube array photoelectrode. The average internal diameter, tube length and wall thickness of the optimized morphology is ∼180nm, 14μm and 10nm, respectively. It was found that the tube diameter increases with the anodization voltage. Diffraction data reveals that the nanotubes consist solely of anatase phase. Back illuminated geometry of dye-sensitized solar cell (DSSC), with nanotubes grown at 60V for 2h, gave a cell performance of 4.5%. TiO2 nanotubes are loaded with silver (Ag) nanoparticles synthesized by a hydrothermal route. The Ag particle size is controlled resulting in solar conversion efficiency to increase by 22%. The DSSC based on TiO2 nanotube with Ag nanoparticles shows power conversion efficiency of 5.5%. Detailed characterization are performed, presented and discussed. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles (nano-Ag) have been widely used in various commercial products including textiles, electronic appliances and biomedical products. However, there remains insufficient information on the potential risk of nano-Ag to human health and environment. In the current study, we have investigated the role of NF-E2-related factor 2 (Nrf2) transcription factor in nano-Ag-induced cytotoxicity. When Nrf2 expression was blocked using interring RNA expression in ovarian carcinoma cell line, nano-Ag treatment showed a substantial decrease in cell viability with concomitant increases in apoptosis and DNA damage compared to the control cells. Target gene analysis revealed that the expression of heme oxygenase-1 (HO-1) was highly elevated by nano-Ag in nonspecific shRNA expressing cells, while Nrf2 knockdown cells (NRF2i) did not increase HO-1 expression. The role of HO-1 in cytoprotection against nano-Ag was reinforced by results using pharmacological inducer of HO-1: cobalt protoporphyrin-mediated HO-1 activation in the NRF2i cells prevented nano-Ag-mediated cell death. Similarly, pharmacological or genetic inhibition of HO-1 in nonspecific control cells exacerbated nano-Ag toxicity. As the upstream signaling mechanism, nano-Ag required the phosphoinositide 3-kinase (PI3K) and p38MAPK signaling cascades for HO-1 induction. The treatment with either PI3K inhibitor or p38MAPK inhibitor suppressed HO-1 induction and intensified nano-Ag-induced cell death. Taken together, these results suggest that Nrf2-dependent HO-1 up-regulation plays a protective role in nano-Ag-induced DNA damage and consequent cell death. In addition, nano-Ag-mediated HO-1 induction is associated with the PI3K and p38MAPK signaling pathways. [Copyright &y& Elsevier]