سید مجید هاشمی

In order to develop alternative drugs against resistant pathogens, capped ZnO nanoparticles (NPs) were prepared using Terminalia catappa leaf extract. By changes in pH and aging time, cauliflower-like, sheet-like, and hierarchical morphologies for ZnO NPs were obtained. Their antibacterial activities against Staphylococcus aureus and Escherichia coli were investigated. The results demonstrated that the green synthesized ZnO NPs exhibit higher antibacterial activity than chemically prepared ZnO NPs. The antibacterial activity of hierarchical ZnO NPs was greater than that of the other morphologies, which was attributed to the higher oxygen vacancy in ZnO NPs leading to enhanced reactive oxygen species (ROS) generation. The mechanism of the formation of ZnO nanocrystals was also discussed.