## 4 Discussion  
This study provided initial evidence that GSH modifications caused by plasma treatment might be used as markers of potential cellular responses. These modifications were due to the myriad plasma components that modify it. The presence and increase of \(\
u\) (S-S) or \(\
u\) (S=O) bands with a decrease in the \(\
u\) (S-H) band correlated with the biological responses of Jurkat T lymphocytes to COST-Jet and nspDBD treatment, respectively. In addition, stronger plasma treatment for both sources increased the magnitude of these modifications and further affected the biological responses, showing that GSH modifications could potentially be scalable and be indicative of the magnitudes of RONS present. The  
Figure 8: Raman spectra analysis of plasma-treated GSH showed more pronounced peaks than mock treatment. GSH was mixed with H\({}_{2}\)O\({}_{2}\), NO\({}_{2}\)\({}^{-}\), or their combination. The spectra were plotted against their corresponding plasma treatment counterparts. The spectra were centered on the observed modifications from plasma treatment: increased in the \(\
u\) (S-S) (508/522 cm\({}^{-1}\)) and \(\
u\) (S=O) (1045 cm\({}^{-1}\)) bands with a decrease in the \(\
u\) (S-H) (2560 cm\({}^{-1}\)) band. For both the nspDBD and the COST-Jet, stronger plasma treatment resulted in more pronounced modifications. (**Top Row**) The nspDBD treatment of GSH resulted in a decrease in the \(\
u\) (S-H) band and an increase in the \(\
u\) (S=O) band with no change in the \(\
u\) (S-S) band. The H\({}_{2}\)O\({}_{2}\) only and the combined mock treatment at these conditions reduced the \(\
u\) (S-H) band with a slight increase in the \(\
u\) (S-S) band, which indicated slight oxidation of the GSH. There was no discernable difference in modifications between the NO\({}_{2}\)\({}^{-}\) treatment when compared with the untreated control. (**Bottom Row**) The COST-Jet-treated samples showed a decrease in the \(\
u\) (S-H) band and an increase in the \(\
u\) (S-S) band. There was no increase in the \(\
u\) (S=O) band. The mock treatment samples did not modify the GSH when compared to the control. absence of these modifications in mock-treated samples strongly suggested the role of the initiator molecules--O and/or OH--in the biological responses. The contrast between observed cellular responses from plasma and mock treatment and the measured chemical concentrations indicated that the interactions between the plasma-generated RONS and the medium components drove the chemistry that the cells experience. Concentrations of H\({}_{2}\)O\({}_{2}\) measured in medium alone from both sources would induce stronger cellular responses than plasma treatment at the corresponding conditions. RONS generated by plasma treatment and medium components must react and reduce the toxicity of H\({}_{2}\)O\({}_{2}\) alone in order to achieve the observed cellular responses with the measured medium H\({}_{2}\)O\({}_{2}\) concentrations. Some of these reactions may form species that cause harm to the cells themselves, such as DNA strand breaks or have other biological outcomes [11; 51; 52; 53; 58]. A unique feature of using GSH as a marker of the potency of plasma treatment is the scalability with plasma treatment parameters. Longer treatment times for the COST-Jet or higher frequencies for the nspDBD resulted in more significant modifications, which supported previous literature that showed similar trends using sulfur compounds [11; 22; 23]. As shown in this study, these stronger treatments triggered higher magnitudes of cellular responses. The treatment of GSH solutions as a model for treatment targets elucidated the roles of short-lived species, as shown in other studies using phenol [24; 59], and their combination with long-lived species. Our results showed there is potential to investigate O for the COST-Jet and OH for the nspDBD as initiator molecules for the biological responses.