The addition of hydrogen peroxide and the incorporation of fluorides by surface plasma jointly promote the bactericidal effects of plasma-treated water

Abstract

The antibacterial ability of plasma-treated water (PTW) is affected by many factors, such as the type of equipment and operating conditions. These factors hinder the application of plasma technology, making it necessary to develop new methods that could prepare PTW with high efficiency for disinfection. In this study, a surface discharge plasma with a dielectric layer of polytetrafluorethylene (PTFE) was used to treat 110 mM H2O2 solution to prepare plasma-treated H2O2 solution (PTH). The bactericidal ability of PTW was evaluated by the inactivation of methicillin-resistant Staphylococcus aureus (MRSA). The results show that the PTH treated by surface plasma for 3 minutes inactivated more than 6.3 orders of magnitude MRSA. Importantly, bubbles were produced when the MRSA suspension was incubated with untreated H2O2 solution, while no bubbles were observed when it was treated by PAH. Further experiments show the amounts of bubbles produced in this process were negatively correlated with the bactericidal effects. The concentrations of several reactive species in PTH were measured to provide useful information for antibacterial mechanism analysis. We suggested that the synergism among hydrogen peroxide, peroxynitrite, as well as unstable reactive fluorides, derived from the gaseous fluorides from the etching of the PTFE dielectric, might play a key role in the bactericidal process. This work provides a new strategy to produce potent disinfectants with low irritation for the disinfection of the environment, object surfaces, and body surfaces.