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We synthesized silver nanoparticles using thirty Chinese plant extracts via a green synthetic strategy. UV–visible spectra showed that the silver nanoparticles have an absorbance at 450 nm. Among the thirty extracts, seven extracts (Cratoxylum formosum , Phoebe lanceolata , Scurrula parasitica , Ceratostigma minus , Mucuna birdwoodiana , Myrsine africana and Lindera strychnifolia) exhibited the successful synthesis of silver nanoparticles. These seven extracts showed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power than the other extracts. The silver nanoparticles synthesized using these seven extracts were mostly spherical with high colloidal stability. The cytotoxicity of these seven silver nanoparticle samples on human lung cancer cells (A549) was clearly higher than that of the extracts alone. Furthermore, the cytotoxicity was affected by the presence or absence of fetal bovine serum. Moreover, the cytotoxicity of the silver nanoparticles synthesized with Cratoxylum formosum and Mucuna birdwoodiana extracts resulted in apoptotic cell death in A549 cells. The wound healing activity observed by the cell scratch method on mouse fibroblast cells (NIH3T3) suggested that the Lindera strychnifolia extract produced silver nanoparticles with decent activity. These results provide ample and systematic information for researchers on the green synthesis of silver nanoparticles using plant extracts. Unlabelled Image • Thirty plant extracts are used for green synthesis of silver nanoparticles. • Synthetic process is totally green and eco-friendly. • Plant extracts play a role as a reducing and a stabilizing agent. • Silver nanoparticles exert biological activities. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) have gained importance in technological advances owing to their user friendly enhanced and efficient physical, chemical, and biological characteristics compared to their bulk counterparts. Biological synthesis of NPs by using a microorganism, enzymes, or plant extracts offers a greener and eco-friendly approach besides many advantages over physical or chemical approaches. This study reports the biosynthesis of silver nanoparticles (AgNPs) using Nostoc muscorum NCCU 442 aqueous extract as the reducing and capping agent for AgNPs synthesis. The synthesized nanoparticles were characterized by UV‐VIS spectrum, SEM, EDS, TEM, AFM, DLS and XRD. Results showed distinguishing polycrystalline nature of synthesized AgNPs with surface plasmon significant band in the size range of 6‐45nm with average 30 size nm. FT-IR study revealed the role of secondary metabolites present in aqueous extract for the synthesis of AgNPs. Biological activities of purified AgNPs as antioxidant and antibacterial potential showed the highest antibacterial activity against Staphylococcus aureus MTCC 902. Unlabelled Image • AgNP biosynthesis optimization and characterizations were done by using Nostoc musco-rum NCCU 442 aqueous extract. • Size, shape and purity of AgNP were characterized by SEM, EDS, TEM, AFM and DLS. • XRD pattern exhibited polycrystalline nature of the AgNP. • FT-IR study revealed that the secondary metabolites of extract were responsible for the synthesis of AgNP. • Biosynthesized AgNP showed significant antioxidant and antibacterial potential. [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]