Rapid and size-controlled biosynthesis of cytocompatible selenium nanoparticles by Azadirachta indica leaves extract for antibacterial activity

Abstract Biosynthesized selenium nanoparticles (SeNPs) have achieved considerable importance in biomedical applications owing to their biocompatibility and low toxicity. In this study, rapid and size-controlled biosynthesis of SeNPs by aqueous leaves extract of Azadirachta indica is reported. SeNPs were synthesized by reduction of Se+ ions of sodium selenite salt to elemental selenium. Biosynthesized SeNPs were crystalline in nature and spherical in shape with a smooth surface. The size of these SeNPs was controlled by adjusting the time of reduction reaction. Accordingly, SeNPs of size range 142 to 168 nm and 221 to 328 nm were synthesized after 5 and 10 min of reaction respectively with 10 mM initial concentration of sodium selenite. Fourier Transform- Infra Red (FT-IR) analysis revealed the presence of plant extract molecules on the surface of SeNPs acting as reducing agent and capping molecules. These biosynthesized SeNPs were found to be cytocompatible in nature when tested in-vitro against the L929 cell line by MTT assay. In addition, these biosynthesized SeNPs showed promising antibacterial activity against selected Gram-positive and Gram-negative bacterial strains.