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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]