Direct and Indirect Bactericidal Effects of Cold Atmospheric-Pressure Microplasma and Plasma Jet

Area of Science:

• Plasma Physics
• Microbiology
• Biomedical Engineering

Background:

• Bacterial infections pose significant health challenges.
• Developing novel antimicrobial strategies is crucial.
• Cold atmospheric-pressure plasmas offer a promising non-thermal inactivation method.

Purpose of the Study:

• To investigate the bactericidal efficacy of dielectric barrier discharge (DBD) cold atmospheric-pressure microplasma against Staphylococcus aureus and Cutibacterium acnes.
• To compare the effectiveness of direct microplasma treatment versus indirect treatment using plasma-activated water (PAW).
• To analyze the chemical changes in plasma-activated water.

Main Methods:

• Generation of microplasma using an AC power supply (0.9-2.4 kV, 27-30 kHz).
• Exposure of bacterial cultures (Staphylococcus aureus, Cutibacterium acnes) to direct microplasma and PAW.
• UV-Vis spectroscopy to analyze chemical species in PAW.

Main Results:

• Direct microplasma treatment demonstrated significant bactericidal effects, achieving a 2-log reduction in CFU/mL.
• Indirect treatment with PAW resulted in a 1-log reduction in CFU/mL.
• Increased treatment time in an argon-oxygen mixture led to decreased O2 concentration and reduced NO2-/NO3- levels in water.

Conclusions:

• DBD microplasma, particularly direct treatment in air, is a highly effective method for inactivating Staphylococcus aureus and Cutibacterium acnes.
• Plasma-activated water also exhibits bactericidal properties, though less potent than direct treatment.
• The study highlights the potential of cold atmospheric-pressure microplasma as a novel antimicrobial technology.