Intracellular Effects of Nanosecond Pulsed Plasma and Electric Field on Cancer Cells in Vitro

Abstract

Nonthermal atmospheric pressure plasma jets (APPJ) produce reactive agents including charged particles, and reactive species, which induce oxidative stress, suggesting their application in cancer therapy. Similarly, nanosecond pulsed electric field (nsPEF) have been studied largely for tumor ablation because of its effect to permeabilize the plasma membrane allowing Ca 2+ influx, and dissipate the mitochondrial membrane potential (ΔΨm) leading to apoptosis or regulated cell death. We have previously shown that synergistic treatments of a nanosecond pulsed plasma jet (ns-APPJ) and nsPEF enhance the inactivation effect on pancreatic cancer cells (Pan02) [1] . This study further examines the effects of the ns-APPJ and nsPEF on Pan02 cells in vitro. Cells were exposed to a single needle-electrode helium plasma jet driven by 200 ns, 9 kV pulses at 2 kHz for ≤ 6 min and 60 ns, 50 kV/cm nsPEF treatment at 1 Hz for ≤ 2 min consecutively. The intracellular ROS and loss of ΔΨm induced by the ns-APPJ and nsPEF are evaluated with respect to cell inactivation using flow cytometry. In addition, the roles of gas-phase ROS produced by the ns-APPJ are assessed using optical emission spectroscopy (OES).