Reduced activity of Staphylococcus epidermidis in the presence of sonicated piezoelectric zinc oxide nanoparticles

Particulate zinc oxide (ZnO) is a known antibacterial agent. Studies have shown that reducing the size of ZnO particles to nanoscale dimensions further enhances their antibacterial properties. ZnO is also piezoelectric. Upon mechanical deformation of ZnO, a transient electrical charge across the material is produced. The purpose of the present in vitro study was to investigate the antibacterial properties of ultrasonically stimulated ZnO nanoparticles. Staphylococcus epidermidis bacteria were seeded at a known cell density into 96-well plates and observed for 48 h with a 10 min ultrasonication period at 24 h. Optical density reading data was collected every 12 h, with an additional reading taken immediately after the ultrasonication period. Bacteria activity was significantly reduced in experimental groups exposed to nanoparticles and ultrasonication compared to groups exposed to nanoparticles or ultrasonication alone. Developing methods and understanding mechanisms for reducing bacteria activity may help reduce potential infection complications following biomaterial implantation.