Combined Effect of Zinc Oxide Nanoparticles and Low Electric Field in Growth Suppression of Some Free-living Pathogens

Abstract

Background: The re-emergence of infectious diseases and the increasing rate of the appearance of many antibiotic-resistant strains are major public health concerns. Zinc oxide nanoparticles (ZnO-NPs) have a great antibacterial effect. Few reports stated the antibacterial effect of low electric field (LEF). Objective: The paper aimed to study the antibacterial effect of LEF at low frequency and investigate the antibacterial effectiveness of using LEF in synergy with ZnO-NPs. Methods: Pseudomonas aeruginosa and Staphylococcus aureus were examined as models for Gramnegative and Gram-positive bacteria, respectively. The bacterial suspension was exposed to different concentrations of Zn-NPs ranging from 100-1600 μg/ml or 2 V/cm, 500 Hz AC electric field for 5 min. ZnO-NPs were prepared and characterized by UV-Vis spectroscopy, XRD, FTIR, TEM, and SEM. The combined effect of LEF exposure with each ZnO-NPs concentration was assessed. Results: 1600 μg/ml ZnO-NPs cause 41.93% and 48.15% death, LEF produces 20.88% and 28.03% death, and the synergetic effect causes 50.41% and 70.27% death for P. aeruginosa and S. aureus, respectively. The death percentages were correlated with DNA concentration and deformation, reactive oxygen species concentration, and ultrastructure changes. Conclusions: LEF has antibacterial properties and can be used in combination with ZnO-NPs to increase its lethal effect.