Green synthesis of silver nanoparticles using Portulacaria afra plant extract: characterization and evaluation of its antibacterial, anticancer activities

Abstract

Applications of nanotechnology in different areas of research have expanded over the last years. Silver nanoparticles (AgNPs) have beneficial effects as antimicrobials, antioxidants and/or anticancer. Yet, one of the major limitations of their use was employing toxic chemicals as reducing agents. Biosynthesis was advantageous over the physical and chemical synthesis. The obtained nanoparticles were characterized using the High-Resolution Transmission Electron Microscope. Disc diffusion method was used to evaluate the antibacterial activity of AgNPs against Bacillus subtilis, Escherichia coli, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus faecalis. Cytotoxic activity of biosynthesized AgNPs was tested against humane breast cancer cell line (MCF-7). Results of characterization showed that AgNPs were irregular spherical in shape, with average diameter of 27.41nm, and width of 4.36nm. The antibacterial assay showed that Portulacaria afra extract had no inhibitory potential against the tested bacteria. However, both AgNO3 and AgNPs exhibited recognized inhibitory potency against all tested bacteria. AgNPs exhibited wider inhibition zones than AgNO3. Cytotoxicity test revealed that green synthesized AgNPs had inhibitory activity against cancer cell line (MCF-7) which was concentration dependent, with IC50 of 75.40 µmole. The aims of the present work were to study the possible green synthesis of AgNPs using P. afra aqueous leaf extract as a reducing agent; to characterize them, to investigate the antibacterial potency and cytotoxic potential of these biosynthesized AgNPs.

Keywords

• silver nanoparticles
• portulacaria afra
• biosynthesis
• antibacterial
• anticancer activity