Air Dielectric Barrier Discharge Plasma Source For In Vitro Cancer Studies

Abstract

For most cancer studies involving plasma treatments, the cell cultures require a significant amount of manipulation before and after treatment. This increases the risk of contamination and of damaging the cells. The well plates are used for growing cell cultures, and a discharge adapted to their geometry would minimize cell culture manipulation during exposures and biological assays. Our laboratory developed an air dielectric barrier discharge (DBD) plasma inside a well plate focusing on treating an entire well plate column at a time.[1] The discharge, presented in Figure 1, was generated using an AC neon transformer (sinusoidal high voltage waveform, 15 kV maximum peak-to-peak output voltage, 50 Hz frequency). For a 96 well plate, the following electrode assembly was designed: a planar electrode was placed under the well plate, and 8 stainless steel cylindrical electrodes were inserted in the wells containing the cells. The geometry of the system provides a volume discharge inside the wells, preventing power losses in the surrounding areas. The well plates act as a dielectric layer for the DBD, while also shielding the cells from any potential damages caused by external factors. Download : Download high-res image (169KB) Download : Download full-size image Figure 1. Air DBD plasma generated inside the well plate This paper focuses on the plasma source diagnosis from the geometrical particularities to electrical and optical investigation of the resulting pulsed plasma. The discharge events are noticeable on the increase and decrease of the HV sinusoidal wave through packages of current peaks with amplitudes between 2 and 250 mA. Molecular nitrogen is the most prominent in the optical emission spectrum, while weak emission is detected from other species such as OH, O,H. Also liquid heating was monitored and, while the local temperature increases, the biological 40oC is not exceeded. Subsequently, the study also approaches the effects produced by this air DBD on HeLa (neoplastic cells) and Vero (normal cells) cell cultures. Cell exposure experiments will emphasise on the selective response, cell viability, apoptosis and TP53 gene expression.