Antibacterial activities of zinc oxide nanoparticles: a mini review

Abstract

Highly reactive oxygen species (ROS) are released from the surface of zinc oxide nanoparticles (ZnO NPs) which cause damage to the microorganisms. ROS may break down the cell wall and cell membrane of the bacteria leading to the leakage of cell contents causing their death. Antibacterial effect of ZnO NPs synthesized from plants’ extracts has been seen against several grampositive (Bacillus coagulans, Staphylococcus aureus, Bacillus subtilis) and gramnegative bacteria (Shigella dysenteriae, Sphingomonas paucimobilis, Salmonella typhimurium, Escherichia coli, Bacillus pumilus, Salmonella typhi). Zinc ions (Zn2+) freed from ZnO NPs may attack DNA and proteins of the cell, thus hindering the growth of the bacteria. The negative charge on the surface of some bacteria (E. coli, S. typhi) interacts with positively charged particles in ZnO NPs inhibiting the growth of these bacteria. The rate of antibiotic activity of ZnO NPs depends on size, the concentration of ZnO NPs, and the type of surfactant used in the synthesis of these ZnO NPs. Due to their antibiotic property, ZnO NPs can be used as antibacterial coating of inner surfaces of refrigerators and dishwashers, plastic food containers, in the lining of food cans used for packaging and preservation of food to prevent their spoilage.