Atmospheric pressure dry-and mist-plasma jets using pulsed power generator and their effects on HeLa cells

摘要

Atmospheric-pressure non-thermal plasma jets have recently received significant attention due to their unique characteristics - low temperature, low cost, portability, and ease of operation - which are suitable to such novel applications as analytical chemistry, thin film processing, nanomaterial synthesis, surface modification, sterilization, and etching. In biological applications, chemical species including NOn₂n, HNOn₃n, On₃nand OH generated in air phase are rapidly converted to liquid phase, and accompanied chemical stimuli can inactivate bacteria. The hydroxyl radical (OH) in particular plays an important role in plasma chemistry and plasma medicine due to its oxidation and disinfection potential, substantially higher than other oxidative species. Also reported is that Hn₂nOn₂nproduced by plasma holds potential for inactivation of human cancer cell viability. Our previous study focused on OH and Hn₂nOn₂nproduction utilizing a system we developed called a “mist plasma jet (MPJ)” which uses dry helium gas mixed with water mist to improve upon the traditional method using only dry helium gas, known as the “dry plasma jet (DPJ)”. We irradiated both plasma to HeLa cells. This study focuses on observation and comparison of effects of both MPJ and DPJ on HeLa cells, a type of human cancer cell, surrounded by cell culture medium 24 hours after irradiation by plasma. First, we examined voltage dependency of saturation temperatures on DPJ and MPJ; next, we irradiated plasma to cell culture medium including cells and observed cells exposed to the plasma-treated culture medium after 24 hours. These experiments revealed that MPJ has a greater influence on cell death than DPJ.