Sodium borohydride mediated synthesis of nano-sized silver particles: Their characterization, anti-microbial and cytotoxicity studies

This work reports the one-step, fast, easy, simple and economical process for the synthesis of nano-sized and stable silver particles. AgNPs were synthesized at six (0.02 M, 0.04 M, 0.06 M, 0.08 M, 0.10 M and 1.00 M) different concentrations of metal precursor and reducing agent. Sodium borohydride was used as both reducing and stabilizing agent. Characterization studies revealed that all the silver nanoparticles (AgNPs) synthesized were in the range of 10 nm–50 nm, spherical shaped, crystalline nature and with high negative surface charge (−30 mV to −47 mV). Among the AgNPs evaluated for their anti-microbial activity through well diffusion method against Escherichia coli (Gram negative bacteria), Bacillus subtilis (Gram positive bacteria) and Candida albicans (fungi), AgNPs-1.00 showed maximum zone of inhibition with 11.5 mm, 18.5 mm and 10 mm at highest test concentration (100 mg/L), respectively. Cytotoxicity of the AgNPs was determined against MCF-7, PVA1 and Caco-2 cancer cell lines through standard MTT assay. AgNPs-0.08 showed highest mortality% with 90% and 80% against MCF-7 and PVA1 at maximum test concentration (100 mg/L), respectively. However, none of the AgNPs showed toxicity towards Caco-2 cancer cell line. Therefore, AgNPs can be used as anti-microbial agents in the biomedical applications.