Facile biofabrication, characterization, evaluation of photocatalytic, antipathogenic activity and in vitro cytotoxicity of zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO NPs) are gaining interest due to their multifunctional properties and desirable biological activities. The present study reports the formulation and characterization of ZnO NPs using an aqueous extract of dry onion peels (Allium cepa L) and further investigates their photocatalytic, in vitro antipathogenic activity and cytotoxicity against human lung cancer A549 cell line. The results of XRD analysis showed the presence of nine intense peaks indicating the crystallized hexagonal phase of ZnO NPs with a size of about 35 nm. Field-emission scanning electron micrographs and the results of EDS showed the hexagonal morphological feature, and the presence of zinc and oxygen in phytogenically synthesized ZnO NPs. The synthesized ZnO NPs showed potent catalytic activity in the degradation of organic dyes (crystal violet and methylene blue). The formulated ZnO NPs indicated a significant bactericidal activity against Bacillus sp., Escherichia coli, Staphylococcus aureus, Vibrio cholerea, Corynebacterium sp., and Salmonella sp. that are common foodborne pathogens. In this study, the obtained IC50 concentration of 51.25 mu g/mL exhibits significant anticancer activity against A549 cells than other tested concentrations because of the release of zinc ions, which induce the cell apoptosis. Furthermore, studies on cell cycle validate that ZnO NPs arrest the cell cycle at the sub-G(1) phase of A549 cells. These results suggest the utility of phytogenic ZnO NPs for various biomedical applications.