Effect of Plasma On-Time with a Fixed Duty Ratio on Reactive Species in Plasma-Treated Medium and Its Significance in Biological Applications

Optimizing the therapeutic range of nonthermal atmospheric pressure plasma (NTAPP) for biomedical applications is an active research topic. For the first time, we examined the effect of plasma on-times in this study while keeping the duty ratio and treatment time fixed. We have evaluated the electrical, optical, and soft jet properties for two different duty ratios of 10% and 36%, using the plasma on-times of 25, 50, 75, and 100 ms. Furthermore, the influence of plasma on-time on reactive oxygen and nitrogen species (ROS/RNS) levels in plasma treated medium (PTM) was also investigated. Following treatment, the characteristics of (DMEM media) and PTM (pH, EC, and ORP) were also examined. While EC and ORP rose by raising plasma on-time, pH remained unchanged. Finally, the PTM was used to observe the cell viability and ATP levels in U87-MG brain cancer cells. We found it interesting that, by increasing the plasma on-time, the levels of ROS/RNS dramatically increased in PTM and significantly affected the viability and ATP levels of the U87-MG cell line. The results of this study provide a significant indication of advancement by introducing the optimization of plasma on-time to increase the efficacy of the soft plasma jet for biomedical applications.