The Effect of Cold Plasma Operating Parameters on the Production of Reactive Oxygen and Nitrogen Species and the Resulting Antibacterial and Antibiofilm Efficiency

Abstract

Background: Cold atmospheric pressure plasma (CAPP) is a novel technology that inactivates bacteria. The mechanisms are primarily due to the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). These kill bacterial cells. Changing parameters of a CAPP device can influence the production of ROS and RNS. We evaluated the parameters of an air-driven CAPP jet and the resulting effects on ROS and RNS production, and on the inactivation of S. aureus and E. coli biofilms. Methods: Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) biofilms were treated with an air-driven CAPP jet with differing gas-flow and power. The resulting viability was measured and correlated to the relative production of atomic oxygen and nitric oxygen. Results: After CAPP treatment, bacterial viability decreased by 99% in E. coli biofilms and 86% in S. aureus biofilms. The relative production of atomic oxygen and nitric oxygen was measured at operational parameters. Decreasing the power supplied decreased the production of atomic oxygen and nitric oxygen, corresponding to a decrease in antibacterial action. Reducing gas-flow increased atomic oxygen production and increased antibacterial action. Conclusions: Changes in operational parameters influence the production of ROS and RNS produced by a CAPP jet. The production of atomic oxygen corresponds with the antibacterial effect. This could be useful in the further development of CAPP systems used for decontamination.