Modified GSH embedded in gelatin elucidates the penetration depth of COST-Jet generated reactive species.

Treatment of biological tissues for cancer treatment and wound healing using non-thermal plasma are limited when considering practical implementation due to the proper `dose' for the application. The correct `dose' is application and plasma source dependent, however the metrics for the proper `dose' are efficacious treatment and limited damage to the tissue. Two major questions required to define the `dose' are: 1) what is the physical penetration depth of plasma-generated species, and 2) what is the penetration depth of the plasma-induced effects? It is established that while plasma species may only penetrate through a fraction of a millimeter, the biological effects are observed up to centimeters into the tissue [1-2]. Several agarose, gelatin, cellular scaffold and spheroid models were developed to answer these questions [3]. In this study, we use a 40{\%} gelatin matrix (for a 60{\%} water content comparable to skin) embedded with glutathione to track the physical penetration of reactive species generated by the COST-Jet. Using 3-D Raman spectroscopy, we observe glutathione modifications in depth as a representation of the physical penetration of reactive species. The COST-Jet was operated under different admixtures to analyze the depth of penetration of different unique chemistries. The resulting Raman spectra will presented. [1] P.Ranieri et al, Plasma Med. 7, 283--297 (2017) [2] A. Lin et al., Oncoimmunology 7.9 (2018) [3] X. Lu et al., Materials Science and Engineering: R: Reports 138, 36-59 (2019)