How does plasma activated media treatment differ from direct cold plasma treatment?

Objective: The aim of the paper is to investigate the optimum condition for generation of Plasma Activated Media (PAM), where it can deactivate the cancer cells while minimum damage for normal cells. Background: Over past few years, cold atmospheric Plasma-Activated Media (PAM) have shown its promising application in plasma medicine for treatment of cancer. PAM has a tremendous ability for selective anti-cancer capacity in vitro and in vivo. Methods: We have analyzed the radicals in air using the optical emission spectroscopy and in culture media using chemical analysis. Further, we have tested the toxicity of PAM using MTT assay. Results: We observed that more cancer cell death is for the Ar plasma followed by the Ar-N₂ plasma, and the least cell death was observed for the Ar-O₂ plasma at all treatment times both by direct treatment and through PAM treatment. The concentration of the RNS species is high for Ar-N₂ plasma in gas as well as inside the culture media compared to that for pure Ar plasma. However, the difference is significantly less between the Ar plasma treatments and the Ar-N₂ plasma treatments, showing that ROS is the main factor contributing to cell death. Conclusion: Among all three feeding gas plasmas the best system is Ar-O₂ plasma for direct treatments towards the cancer cells. In addition, the best system for PAM preparation is Ar-N₂ at low time treatments (1 min and 2 min) because it has no effect on normal cells, but kills the cancer cells.