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

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 S. aureus (MRSA). The results show that the PTH treated by surface plasma for 3 min inactivated more than 6.3 orders of magnitude MRSA. Importantly, bubbles were produced when the MRSA suspension was incubated with the untreated H₂O₂ solution, while no bubbles were observed when the suspension was incubated with the PTH. 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 for antibacterial mechanism analysis and provided a clue 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.