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Silver nanoparticle has been widely applied to a variety of fields for its outstanding antimicrobial activity. However, the stability of silver nanoparticle limits its application under certain conditions. Thus, improving the stability of silver nanoparticle via biosynthesis is a promising shortcut to expand its application. Sericin from silkworm cocoon has good hydrophilicity, reaction activity, biocompatibility and biodegradability. In this study, we developed a novel, simple, one-step biosynthesis method to prepare sericin-silver nanoparticle composite in situ in solution. Sericin served as the reductant of silver ion, the dispersant and stabilizer of the prepared sericin-silver nanoparticle composite. Natural light was the only power source used to catalyze the synthesis of silver nanoparticle in situ in solution. The novel sericin-silver nanoparticle composite was characterized by ultraviolet-visible and fluorescence spectroscopy, X-ray diffraction, transmission electron microscopy and fourier transform infrared spectroscopy. The results showed silver nanoparticle could be synthesized through the reduction of AgNO 3 by the phenolic hydroxyl group of tyrosine residues of sericin under the catalysis of natural light. The synthesized silver nanoparticle had good crystalline, size distribution and long-term stability at room temperature. Light irradiation was essential for the preparation of sericin-silver nanoparticle composite. The antibacterial activity assay showed 25 mg/L and 100 mg/L were the minimum concentrations of sericin-silver nanoparticle composite required to inhibit the growth of Staphylococcus aureus and kill this bacterium, respectively. The cytotoxicity assay showed cell viability and cell growth were almost not affected by sericin-silver nanoparticle composite under the concentration of 25 mg/L. Our study suggested the preparation of sericin-silver nanoparticle composite was environmentally friendly and energy conservation, and the prepared sericin-silver nanoparticle composite had long-term stability, effective antibacterial activity and good biocompatibility. This novel sericin-silver nanoparticle composite has shown great potentials for biomedical application such as antibacterial agent and wound care. [ABSTRACT FROM AUTHOR]

Biosynthesis of metal nanoparticles is expected as a cost efficient and ecofriendly option in the research study. Therefore, the aqueous extracts made from leaf of Aesculus hippocastanum (horse chestnut) were used as the reducing factors to synthesize silver nanoparticles (AgNPs) and their antioxidant, antibacterial and the application of resveratrol combined AgNPs as efficient delivery vehicles have also been evaluated. The biosynthesized AgNPs were characterized by UV–Visible Spectroscopy, Fourier-Transform Infrared Spectroscopy (FTIR), X Ray Diffraction (XRD), Zeta potential, and Scanning Electron Microscopy (SEM). The AgNPs were found to be stable at −29.1 mV through zeta potential study. According to the UV-Vis measurements, AgNP formation was observed at a wavelength range of 420–470 nm. The Ag NPs were spherical with a size of 50 ± 5 nm. AgNPs exhibited strong antibacterial activity against all tested bacterial species but have no effect against fungal strains. AgNPs showed an important inhibitive activity counter the DPPH radical and thereby indicate a source for antioxidants. The free radical scavenging activity of AgNP was calculated as 54.72% at the highest concentration (100 ppm). The superoxide radical scavenging activity of AgNPs was found to be increased with increasing concentrations and the average inhibition was about 62.9% as compared to the activity of plant extract. In vitro investigations on the drug delivery from AgNPs exhibited pH dependency; the release was significant (45.6%) below acidic terms (pH 5.2) when in proportion to physiological terms (pH7.4). It was observed that the resveratrol-combined to AgNPs stays on the nanoparticle surface for a lengthy time in the plasma at physiological pH (7.4), so very reducing the flank influence on the normal tissues. It can be concluded that horse chestnut leaves has reduction potential as well as being a capping agent to produce well-defined nanoscale silver particles. Our biosynthesized Ag NPs can be used antibacterial, antioxidant agent and also for as effective delivery vehicles in the near future. • Green synthesis of AgNPs using Aesculum hippocastanum leaf extract. • The synthesized nanoparticles were analyzed by FT-IR, XRD, Zeta Potantial and SEM. • Obtained AgNPs showed significant antioxidant and antimicrobial activities. • In vitro observations on the drug release from AgNPs exhibited pH dependency. [ABSTRACT FROM AUTHOR]