Effect of Zn salts and hydrolyzing agents on the morphology and antibacterial activity of zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnONPs) are considered safe as antibacterials. Those nanoparticles should preferably have uniform size and shape, but conditions to obtain uniform nanoparticles and their antibacterial activity are poorly known. Therefore, here we prepared various types of ZnO nanoparticles using three different zinc salts, zinc acetate, zinc chloride, and zinc nitrate, and two hydrolyzing agents, potassium hydroxide and sodium hydroxide, to test the effect of the morphology on antibacterial activity. Results show that all ZnO nanoparticle solutions showed characteristic absorption peaks in the range of 360–380 nm. The shape and size of nanoparticles depend on the source of zinc and hydrolyzing agents. Nanoparticles exhibited distinctive antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermis) bacteria and showed stronger antimicrobial activity against Gram-negative bacteria than Gram-positive bacteria.