Plasma interactions with L-alanine in aqueous solution have been examined as a basis of fundamental processes in plasma medicine. The plasma interactions with L-alanine in aqueous solution have been examined for investigations of chemical modifications induced by exposures with the atmospheric-pressure hollow-cathode He plasma to the surface of the aqueous solution, which contained L-alanine as a solute in pure water, via chemical bonding states analyses using x-ray photoelectron spectroscopy (XPS). Measurement of hydrogen ion exponent (pH level) of pure water during the atmospheric plasma exposure showed that the pH level decreased to be acidic, but the water temperature did not change. The C 1s XPS spectrum from the L-alanine after the plasma exposure to the aqueous solution showed the decomposition of the -COOH group and the formation of -C=O group.

Epithelial ovarian carcinoma (EOC) is the leading cause of cancer-related death in women in Western countries. Once patients experience recurrence, complete cure is almost impossible. We elucidated the effect of nonequilibrium atmospheric pressure plasma on the growth of EOC, particularly in plasma-activated medium (PAM). Furthermore, we examined the role of reactive oxygen species (ROS) or their scavengers in chronic antineoplastic-resistant EOC cells. As a result, we showed PAM induced the antitumor effect of EOC cells in vitro and in vivo, even in chemoresistant cells. To apply the plasma treatment for advanced or recurrent EOC, we suggest adopting indirect plasma therapy instead of direct plasma considering intraperitoneal administration in the future. However, there are several problems under investigation, including intracellular mechanism of antitumor effect by PAM and adverse event in vivo.

In this paper, we report the spatial distribution of OH radical density in atmospheric-pressure DC glow discharge using a miniature helium flow and an electrolyte cathode. Laser-induced fluorescence imaging was applied for the measurement of the OH radical density. The effect of collisional quenching was considered in obtaining the spatial distribution of the OH density. The spatial distribution of the OH radical density showed that the peak of the OH density was located at a separated distance from the electrolyte surface. However, the OH radicals kept contact with the electrolyte surface. It was suggested that the OH radicals were generated mainly in a region separated from the electrolyte surface and some fraction of the generated OH radicals reached to the liquid phase.