Comparison of Three Radio-Frequency Discharge Modes on the Treatment of Breast Cancer Cells in Vitro

Abstract

Nonthermal plasmas (NTPs) are known for their ability to induce thermal-free cytotoxic effects on cancer cells. However, as the variety of NTP devices increases, the comparison of their cytotoxic effect becomes increasingly essential. In this article, we compare the cytotoxicity of three different radio-frequency (RF) NTPs. MDA-MB-231 triple-negative breast cancer cells are treated in suspension in DMEM culture medium by the effluents of a single RF discharge device operating in three modes, namely the $\Omega $ and $\gamma $ modes of the capacitively coupled RF (CCRF) discharge and an RF plasma jet mode. All three discharge modes reduce the proliferative capacity of MDA-MB-231 cells, but the treatment time required to reach the same efficacy is more than ten times longer using the $\Omega $ and the $\gamma $ modes than using the jet mode. In all cases, using the appropriate treatment time, cells exhibit an impaired proliferation and eventually start to show signs of cell death (about 48 h after treatment). The three discharge modes also induce nuclear DNA damages. Plasma-produced H2O2 was not found to contribute to the cytotoxicity of the treatment. Furthermore, short-lived reactive species (liquid phase species with a lifetime below 1 s) are expected to play an important role in the anti-cancer effect of all three discharge modes.