Optimization of a cold atmospheric plasma treatment to selectively affect the viability of skin cancer cells

Cold atmospheric plasmas (CAPs) are a specific type of non-thermal plasmas mainly composed by reactive oxygen and nitrogen species (ROS and RNS, respectively), UV radiation and charged particles. In the last years, liquids treated by CAPs (indirect CAPs treatments) have attracted a significant interest in oncology due to its ability to kill cancer cells with an effectiveness similar to direct irradiation of the cells by cold plasmas. It is important to point out that indirect treatments have the advantage of avoiding the effects of UV radiation and the electrical fields present in plasmas being their effects mainly dependent on the ROS and RNS produced in the liquid phase. To better understand the mechanisms behind the interaction between CAPs, treated liquids and cells, it was engineered a plasma jet device and studied the vulnerability of different cell lines to the culture medium previously exposed to CAPs. For that, it was analysed the concentration of H2O2 produced during the treatments by means of colorimetric assays and evaluated the influence of using different working parameters such as volume of medium and gap. According to the obtained results it could be observed that the cancer cell line (Met-1) in study is more sensitive to the liquids treated by CAPs than the non-cancer one (HGF-1), which in the particular case of this jet, seems to be mainly related with the concentration of RNS species produced in the liquids during the plasma exposure since the concentration of the H2O2 produced is very low.