Investigation of the discharge characteristics of a nozzle-broadened plasma jet and its anticancer potential

Atmospheric pressure cold plasma technology has demonstrated promising anticancer effects in cancer therapy, but the small effective treatment area limits its ability to meet the need for larger treatment zones in practical applications. In this study, a hollow needle-ring electrode structure was used to achieve a laterally broadened discharge at low gas flow rates through a slit dielectric tube nozzle. At an argon gas flow rate of 3 standard liters per minute (SLM), the nozzle was fully filled with visible plasma filaments, so there was no need to increase the gas flow rate, which reduced the cost investment. By maintaining the argon gas flow rate at 3 SLM, the effect of different voltages on discharge characteristics was studied. It was found that increasing the voltage improved the uniformity of the lateral discharge and the intensity of reactive species. At 12 kV, the discharge area reached 25 (laterally) × 7 mm2 (vertically), achieving a uniform and effective widening of the plasma treatment area. In addition, the measured values for human-safe current and gas temperature met the requirements for safety, making the plasma suitable for biomedical applications. With the increase in plasma treatment time, the concentrations of H2O2, NO2−,and ONOO−/O2− also increased. 57% of A549 cells cultured in vitro can be inactivated within 4 min by apoptosis, demonstrating the device’s effective anticancer potential.