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[Display omitted] The size of silver nanoparticles (Ag NPs) and loading amount of Ag NPs onto their substrate/carrier are two key factors for their efficient applications. Herein, we present a facile method for in situ synthesizing ultrafine and highly loaded Ag NPs on the surface of tannin-coated catechol-formaldehyde resin (TA-CFR) nanospheres. TA-CFR nanospheres act as green and highly efficient reducing agents for converting silver ions (Ag+) into Ag NPs, and the size of resultant Ag NPs is only ∼ 7.5 nm, and the Ag NPs loading capacity of TA-CFR is as high as 61.5 wt%, both of which contribute to the very high specific surface area of Ag NPs. Consequently, the as-synthesized TA-CFR@Ag composites show high catalytic performance, and the catalytic rate for the reduction of 4-nitrophenol is almost 10 times higher than that of the control. Meanwhile, TA-CFR@Ag composites also possess high antibacterial activity, efficiently inhibiting the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, tannin coating (thickness: ∼ 15 nm) minimizes the aggregation of Ag NPs, and enhances the reusability and stability of resultant Ag NPs, because of their high surface charges (the zeta potential is up to −65.5 ± 1.9 mV) and strong coordination capability with Ag NPs. This work provides a new frontier to develop multifunctional nanomaterials focusing on the green catalyst synthesis and environmental-remedy applications. [ABSTRACT FROM AUTHOR]

Silver nanoparticles with vanadium oxide nanowires were obtained using the vanadium oxide quantum dots as both reductants and stabilizers. It was loaded into electrospun dressing for efficient bacteria-infected wound healing as confirmed by both in vitro and in vivo tests. [Display omitted] Silver nanoparticles (AgNPs) have been widely recognised as effective antibacterial materials in textiles for enhancing wound healing. However, high loadings of AgNPs are toxic and expensive. Thus, it is ideal to prepare AgNPs in a favourable nanostructure for stable and effective conjugation with the textile carrier by selecting a reductant and stabiliser that contributes to the antibacterial effect. Here, silver nanoparticles/vanadium oxide nanowires (Ag/VO x NWs) were prepared via a one-step reduction strategy using vanadium oxide quantum dots (VO x QDs) as both the reductant and stabiliser. VO x QDs possess antibacterial properties, which aid in minimising the applied silver content while enhancing bactericidal performance. Silver can self-aggregate into nanoparticles as well as promote the formation of vanadium oxide nanowires (VO x NWs). Accordingly, the Ag/VO x NWs exhibited remarkable antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The nanowire structure of the Ag/VO x NWs was favourable for effective loading into a sodium alginate (SA) gel fabric to form a wound dressing. The effective loading of Ag/VO x NWs on SA was conducive to the complete dispersion of the bacteriostatic agent and enhanced the antibacterial activity of AgNPs. The wound dressing efficiently suppressed the growth of wound bacteria and promoted wound healing in vivo. [ABSTRACT FROM AUTHOR]

Highlights: [•] The additive anions were found to be of significant importance in determining the final products. [•] A new pathway was proposed for the formation of Ag0 that AgxAy act as the oxidant. [•] The formation mechanism was analyzed from the viewpoint of standard reduction potential. [•] The obtained AgNWs showed excellent and long-lasting bactericidal efficiency for both Staphylococcus aureus and Escherichia coli. [Copyright &y& Elsevier]

Abstract: A two-step, easy synthetic strategy in solution has been optimized to prepare authentic monolayers of silver nanoparticles (NP) on MPTS-modified glass surfaces, that were investigated by AFM imaging and by quantitative silver determination techniques. NP in the monolayers remain firmly grafted (i.e. not released) when the surfaces are exposed to air, water or in the physiological conditions mimicked by phosphate saline buffer, as UV–Vis spectroscopy and AFM studies demonstrate. About 15% silver release as Ag+ ions has been found after 15days when the surfaces are exposed to water. The released silver cations are responsible of an efficient local microbicidal activity against Escherichia coli and Staphylococcus aureus bacterial strains. [ABSTRACT FROM AUTHOR]

Abstract: Photodegradation of Escherichia coli bacteria in presence of Ag–TiO2/Ag/a-TiO2 nanocomposite film with an effective storage of silver nanoparticles was investigated in the visible and the solar light irradiations. The nanocomposite film was synthesized by sol–gel deposition of 30nm Ag–TiO2 layer on ∼200nm anatase(a-)TiO2 film previously doped by silver nanoparticles. Both Ag/a-TiO2 and Ag–TiO2/Ag/a-TiO2 films were transparent with a SPR absorption band at 412nm. Depth profile X-ray photoelectron spectroscopy showed metallic silver nanoparticles with diameter of 30nm and fcc crystalline structure were self-accumulated on the film surface at depth of 5nm of the TiO2 layer and also at the interface of the Ag–TiO2 and a-TiO2 films (at depth of 30nm). Both OH− bounds and H2O contents were concentrated on the film surface and at the interface, as a profit in releasing more ionic (not metallic) silver nanoparticles. Antibacterial activity of the nanocomposite film against E. coli bacteria was 5.1 times stronger than activity of the a-TiO2, in dark. Photo-antibacterial activity of the nanocomposite film exposed by the solar light was measured 1.35 and 6.90 times better than activity of the Ag/a-TiO2 and a-TiO2, respectively. The main mechanism for silver ion releasing was inter-diffusion of water and silver nanoparticles through pores of the TiO2 layer. Durability of the nanocomposite film was at least 11 times higher than the Ag/a-TiO2 film. Therefore, the Ag–TiO2/Ag/a-TiO2 photocatalyst can be nominated as one of the effective and long-lasting antibacterial nanocomposite materials. [Copyright &y& Elsevier]