Biological effects of the combination with low temperature plasmas and nanoparticles-platinum and gold-

Interaction between low temperature plasmas (LTP) and nanoparticles is an interesting topic. Platinum nanoparticles (Pt-NPs) are potent antioxidants due to their unique ability to scavenge superoxides and peroxides. First, the effects of Pt-NPs on He-LTP-induced apoptosis and the underlying mechanism were examined in human lymphoma U937 cells. The results indicate that Pt-NPs substantially scavenge LTP-induced ROS and inhibit all the pathways involved in apoptosis execution. Second, gold nanoparticles (Au-NPs) have attracted attention as a promising radiosensitizer owing to their high atomic number. Here, the activity of different sized Au-NPs with He-LTP was analyzed, and the underlying mechanism was investigated. Treating cells with only small Au-NPs (2 nm) significantly enhanced He-LTP-induced apoptosis. In comparison, 40 nm and 100 nm Au-NPs failed to enhance cell death. Mechanistically, the synergistic enhancement was due to 2 nm Au-NPs-induced decrease in intracellular glutathione, which led to the generation of intracellular ROS. The combined treatment significantly enhanced the intracellular ROS formation and apoptosis. These findings indicate that metal NPs are the potential modifiers of biological effects of LTP to regulate intracellular ROS.