Effects of atmospheric nonthermal plasma on invasion of colorectal cancer cells

Abstract

The effect that the gas content and plasma power of atmospheric, nonthermal plasma has on the invasion activity in colorectal cancer cells has been studied. Helium and helium plus oxygen plasmas were induced through a nozzle and operated with an ac power of less than 10 kV which exhibited a length of 2.5 cm and a diameter of 3-4 mm in ambient air. Treatment of cancer cells with the plasma jet resulted in a decrease in cell migrationinvasion with higher plasma intensity and the addition of oxygen to the He flow gas.

Figure 1

(a) Schematic diagram of the plasma torch. (b) Image of the plasma jet with helium and oxygen.

Figure 2

Plasma emission spectra with different gases, (a) comparison of He vs He+O₂ gases and (b) plot of peak ratio vs wavelength [I_ratio,(He+O₂)∕He] at 5 kV.

Figure 3

Comparison of atmospheric pressure plasma emission spectrum of He+O₂ gases with different voltages at 5 and 10 kV.

Figure 4

Cell migration of colorectal cancer cells. (a) Photographs of the SW480 cells at 24 and 48 h after treatment. 100× magnification. (b) Quantification of cell migration assay from three independent experiments. ^*p<0.05. ^**p<0.01, and ^***p<0.001 by student t test compared to control. NS, no significant; AU, arbitrary unit.

Figure 5

Invasion assay for SW480. (a) Photographs of the SW480 cell at 48 h after treatment. 100× magnification. (b) Quantification of invasion assay from three independent experiments. ^**p<0.01, ^***p<0.001 by student t test compared to control. NS, no significant.