Sterilization effect of various gas non-thermal plasma

Summary form only given. In recent years, atmospheric non-thermal plasma have been attracted attention in medical field because of its effectiveness for sterilization and wound treatment. However, conventional plasma sources have a limitation in plasma gas species. Plasma can be generated with specific gas such as helium, argon, nitrogen, or air. In our group, the damage-free multi-gas plasma jet source was developed in 2010. This plasma source is free from thermal or electric discharge damage to target materials. Therefore, the plasma treatment is applicable for various materials such as semiconductor, metal, plastic, paper, textile, living body and tissue. And it can generate stable atmospheric plasma jet with helium, argon, oxygen, neon, nitrogen, carbon dioxide, air, and their mixture gas. In surface treatment using the damage-free multi-gas plasma jet, obvious difference of hydrophilization effect by plasma gas species was observed. So, in this study, we examined some biological effects of various gas plasmas. 5 L/min of argon, oxygen, nitrogen, air and oxygen mixed argon plasma were irradiated to E. Coli in agar medium. A clear difference was seen by plasma gas species in the bactericidal effect. Oxygen mixed argon plasma was most effective for sterilization of E. Coli. E. Coli in 90 mm agar medium was sterilized in 10 seconds plasma irradiation. This plasma showed good sterilization effect for other bacteria such as B. subtilis, S. aures, A. niger, and G. stearo. Shape change of bacteria was observed using electron microscope after plasma irradiation. To explore the possibility of plasma irradiation for therapeutic application, its effect on cultured human cell line was investigated. As a result, 90 % of HeLa cells were killed in 40 seconds by irradiation of oxygen mixed argon plasma. The details of the plasma source and the results of these experiments will be presented.