Low-Temperature Atmospheric Pressure Helium Plasma Jet Damages Malignant Melanoma Cells by Inducing Oxidative Stress

This paper is aimed to identify the mechanism that atmospheric pressure plasma jet (APPJ) damages malignant melanoma (B16-BL6 cells) cultured in vitro through the induction of oxidative stress. After being exposed to APPJ with different time durations, the reactive species of H₂O₂ and NO₂ ^- inside cell culture medium, together with a series of biochemical parameters including the cell viability, cell morphology, DNA damage, intracellular reactive oxygen species (ROS) and antioxidant capacity, are measured. The results reveal that there are obvious increases of H₂O₂ and NO₂ ^- in the plasma-irradiated medium. And the cell viability, intracellular total antioxidant capability (T-AOC), and glutathione (GSH) contents decrease with the exposure to APPJ in a time-dependent manner compared with the untreated cells, i.e., 0-s group (p < 0.05). Besides, the intracellular malondialdehyde (MDA), ROS contents, and the degree of cellular damage increase significantly with 30, 60, and 90 s of plasma treatment (p < 0.05). Furthermore, the pretreatment with N-acetyl cysteine, which is a free radical scavenger, can markedly prevent the decrease of cell viability, T-AOC, and GSH content, the increase of MDA, ROS contents, and the degree of cellular damage caused by 90-s exposure to APPJ. These research findings suggest that low-temperature plasma exerts its cytotoxic effects on melanoma cancer cells mainly through the ROS inside cells induced by reactive oxygen and nitrogen species generated in gaseous and liquid phases, which ultimately cause oxidative stress-evoked damage to cellular components.