Effect of a plasma-activated medium produced by direct irradiation on cancer cell killing

We describe the effects of the plasma-activation of a medium on the killing of cancer cells, in which the plasma-activated medium is produced by the irradiation of the cell culture medium using a low-frequency (LF) or very-high-frequency (VHF) plasma jet. The plasma-activated medium produced by the direct contact of the LF plasma jet with the liquid surface induces much lower cancer cell viability, and large amounts of oxidation products, such as gluconic acid and methionine sulfoxide, can be detected in the plasma-activated medium. Our experiments show that the process of using plasma created by the direct contact of a LF plasma jet leads to a plasma-activated medium with stronger cancer-cell killing ability compared with a no-contact process. Also, the oxidation products, such as methionine sulfoxide in the plasma-activated medium become useful proxies for lethality.