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

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