Atmospheric pressure plasma treatment increases the antioxidant capacity of the serum in vitro.

The interaction of atmospheric pressure plasma (APP) with the liquids has been fully studied, and multiple biomedical applications of APP-activated liquids have also been verified. However, there is still no direct evidence regarding the interaction between APP treatment and serum. In the present study, the rat serum was treated with the helium APP device. Compared with APP-treated saline, the elevation of reactive oxygen species (ROS) levels in serum was significantly smaller, implying that an antioxidant system existed in serum. The proteomics suggested that differently expressed proteins were predominantly enriched in the glutathione metabolism pathway. Our results showed that APP treatment significantly increased the serum GSH level and GSH/GSSG ratio, suggesting the enhanced antioxidant capacity of the APP-treated serum. Furthermore, the antioxidant enzymes in APP-treated serum were examined. As a result, both the glutathione peroxidase (GPX) protein level and enzyme activity were up-regulated according to the parallel reaction monitoring (PRM) analysis and GPX enzyme activity analysis. Meanwhile, the activities of glutathione reductase (GR) and superoxide dismutase (SOD) enzymes were also enhanced after APP treatment, while the catalase (CAT) activity decreased. Meanwhile, the total antioxidant capacity (T-AOC) also increased, as confirmed by the evidence of the superior ROS scavenging by APP-treated serum. Our data highlight that APP treatment can enhance the antioxidant capacity of the serum, which is closely related to the up-regulated GSH level, GSH/GSSG ratio and antioxidant enzymes within serum after APP treatment.