Synergistic Effects of an Atmospheric-Pressure Plasma Jet and Pulsed Electric Field on Cells and Skin

Nonthermal atmospheric-pressure plasmas produce reactive plasma species including charged particles and reactive oxygen and nitrogen species, which are known to induce oxidative stress in living cells in liquid or tissue. In the meantime, pulsed electric fields have been widely used in reversible or irreversible electropermeabilization for either the delivery of plasmid DNA or inactivation of cancer cells. This work discusses the synergistic effects of nanosecond pulsed plasma jets and pulsed electric field on inactivation of pancreatic cancer cells
in vitro
and enhancement of plasmid DNA delivery to guinea pig skin
in vivo
. Higher inactivation rates of the cancer cells in suspension were obtained with combined treatment of 300-ns 50-kV/cm pulsed electric field and a 1-min exposure of a nanosecond pulsed, 250-
$\mu \text{m}$
plasma jet. Increased efficiency of gene electrotransfer to skin was also observed after a 3-min treatment of a nanosecond pulsed, 1-mm plasma jet. Application of the plasma alone at the same dosage did not have significant effect on gene delivery. These findings signify the dosage-dependent cell response to both the electric fields and plasma. Importantly, the use of cold plasma to increase the sensitization of the biological cells in response to pulsed electric fields could be an effective approach to enhance the desired effects in electroporation-based applications.