A grounded electrode beneath dielectric targets, including cancer cells, enhances the impact of cold atmospheric plasma jet

Abstract

The effect of placing a grounded substrate beneath the dielectric target or cancer cells during exposure to the cold atmospheric plasma jet is studied in the experiments and in fluid model simulations for the discharge parameters typical for the medical applications. It is shown that the dynamics of streamers generated in each positive cycle of ac voltage depends on the grounded substrate position. The streamers approach the target more often if the grounded substrate is beneath the target, that provides more intensive plasma-target interaction. In this case, the measured spectrum of plasma jet emission near the target demonstrates much higher intensity compared to an electrically isolated target case. The calculated and measured discharge currents with time demonstrate a mismatch of frequencies of the ac voltage and current over the target. The effect of relocation of the grounded substrate on the viability of plasma-irradiated cancer cells is analyzed. The viability of A431 human skin carcinoma and MX7 mouse rhabdomyosarcoma cells treated by cold atmospheric plasma jet is measured with MTT assay 24 hours after. The results show an enhanced suppression of the cell viability with using the grounded substrate for both cell lines. Achieving effective death of tumor cells with a shorter irradiation time can be considered an advantage of using a grounded electrode.

Pulsed voltage cold atmospheric plasma jet and gold nanoparticles enhance cytotoxic anticancer effect

“…This led to the intensification of active radical generation in the contact zone of the CAPJ with the target compared to the case with a target under a floating potential. Previously we studied the effect of presence of a grounded electrode beneath the target (see [30,32]). The distance from the nozzle to the target of 2.5 cm was chosen so that the plasma jet touched the target, providing the maximum OH generation at a given gas flow rate and a minimum heating of the target.…”

Chloroquine Enhances Death in Lung Adenocarcinoma A549 Cells Exposed to Cold Atmospheric Plasma Jet

“…Differences between the effects of plasma on healthy cells and tumor cells also remain a matter of debate. The efficiency of antitumor CAP treatment, which is associated with CAP toxicity to cancer cells, depends on the chosen parameters of the plasma device operation, such as voltage frequencies and amplitudes, the composition of the working gas and its pumping rate, the dimensions of the nozzletarget gap and the type of target [6][7][8][9][10]. The optimization of irradiation modes is aimed at increasing the cytotoxic effect on tumor cells without affecting healthy cells.…”