Green synthesis of selenium nanoparticles using Acinetobacter sp. SW30: optimization, characterization and its anticancer activity in breast cancer cells.

The aim of this study was to synthesize selenium nanoparticles (SeNPs) using cell suspension and total cell protein of Acinetobacter sp. SW30 and optimize its synthesis by studying the influence of physiological and physicochemical parameters. Also, we aimed to compare its anticancer activity with that of chemically synthesized SeNPs in breast cancer cells. Cell suspension of Acinetobacter sp. SW30 was exposed to various physiological and physicochemical conditions in the presence of sodium selenite to study their effects on the synthesis and morphology of SeNPs. Breast cancer cells (4T1, MCF-7) and noncancer cells (NIH/3T3, HEK293) were exposed to different concentrations of SeNPs. The 18 h grown culture with 2.7×109 cfu/mL could synthesize amorphous nanospheres of size 78 nm at 1.5 mM and crystalline nanorods at above 2.0 mM Na2SeO3 concentration. Polygonal-shaped SeNPs of average size 79 nm were obtained in the supernatant of 4 mg/mL of total cell protein of Acinetobacter sp. SW30. Chemical SeNPs showed more anticancer activity than SeNPs synthesized by Acinetobacter sp. SW30 (BSeNPs), but they were found to be toxic to noncancer cells also. However, BSeNPs were selective against breast cancer cells than chemical ones. Results suggest that BSeNPs are a good choice of selection as anticancer agents.