Published online by Cambridge University Press: 21 May 2012
We have investigated the nonthermal bioplasma sources and their characteristics as well as their interactions with biological cells. The electron temperature and plasma density are measured to be about 1.5 eV and 3×1012 cm-3 , respectively, for the direct palsma jet under Ar gas flow. The hydroxyl radical density has also been investigated and measured to be maximum value of about 3 ×1015 cm-3 and 8 ×1014 cm-3 in the direct plasma jet and dielectric barrier discharge bioplasma, respectively, by the ultraviolet optical absorption spectroscopy. Herein, we have investigated the basic interactions of these nonthermal bioplasma with the living organisms in morphological and biomolecular aspects. We found that the secondary electron emision coefficient of the biological surface has been drastically increased by atmospheric bioplasma, which indicates the biological surface to be oxidized especially by the hydroxyl (OH) radical species. In order to elucidate the basic mechanisms for the cell shrinking and apoptosis leading to a cell death by the nonthermal bioplasma, the cell membrane potential has been estimated based on the ROS density as well as cell capacitances. It is also found that the molecular electron energy band structure in the biological cells have been shifted closer toward the vacuum surface and accordingly their central energy of molecular band becomes small by the nonthermal bioplasma due to cell oxidation caused by OH radicals.