Direct and Indirect Bactericidal Effects of Cold Atmospheric-Pressure Microplasma and Plasma Jet |
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| Authors: | Ahmad Guji Yahaya Tomohiro Okuyama Jaroslav Kristof Marius Gabriel Blajan Kazuo Shimizu |
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| Affiliation: | 1.Graduate School of Science and Technology, Shizuoka University, Hamamatsu 832-8561, Japan;2.Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu 432-8561, Japan;3.Organization for Innovation and Social Collaboration, Shizuoka University, Hamamatsu 432-8561, Japan; (J.K.); (M.G.B.) |
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| Abstract: | The direct and indirect bactericidal effects of dielectric barrier discharge (DBD) cold atmospheric-pressure microplasma in an air and plasma jet generated in an argon-oxygen gas mixture was investigated on Staphylococcus aureus and Cutibacterium acnes. An AC power supply was used to generate plasma at relatively low discharge voltages (0.9–2.4 kV) and frequency (27–30 kHz). Cultured bacteria were cultivated at a serial dilution of 10−5, then exposed to direct microplasma treatment and indirect treatment through plasma-activated water (PAW). The obtained results revealed that these methods of bacterial inactivation showed a 2 and 1 log reduction in the number of survived CFU/mL with direct treatment being the most effective means of treatment at just 3 min using air. UV–Vis spectroscopy confirmed that an increase in treatment time at 1.2% O2, 98.8% Ar caused a decrease in O2 concentration in the water as well as a decrease in absorbance of the peaks at 210 nm, which are attributed NO2− and NO3− concentration in the water, termed denitratification and denitritification in the treated water, respectively. |
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| Keywords: | DBD microplasma plasma jet sterilization plasma activated water UV-Vis spectroscopy reactive oxygen nitrogen species |
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