Green synthesized ZnO nanosheets from banana peel extract possess anti- bacterial activity and anti-cancer activity

Recently, green synthesis of metal oxide nanoparticles has gained extensive attention because it is an environment-friendly and cost-effective approach. This study therefore focused on green synthesis of zinc oxide nanoparticles (ZnO NPs) by using waste material, banana peel crude extract, as reducing as well as capping agents in the reaction with zinc acetate. The synthesized ZnO NPs with the average electronic band gap similar to 3 eV were obtained and found to have rod-like or sheet-like structures depended on concentration of crude extract used in the reaction. By performing antibacterial activity assay, these green synthesized ZnO nanosheets inhibited growth of gram-positive bacteria, Bacillus subtilis, Staphylococcus epidermidis and gram-negative bacterium, Escherichia coli. Moreover, the synthesized ZnO nanosheets demonstrated potent anti-cancer activity against cell viability of skin cancer cell (A431), colorectal cancer cell (SW620) and liver cancer cell (HepG2) without affecting normal cell line (Vero). Therefore, these studies firstly reported potential usage of the green synthesized ZnO nanosheets for development of anti-bacterial substances or anticancer drugs. Moreover, this study showed the opportunity to increase values of agricultural waste.