ROS from Physical Plasmas: Redox Chemistry for Biomedical Therapy

Figure 4

Models for the study of the penetration of plasma-generated ROS into tissue. (a) In vitro approach for the analysis of ROS penetration using 0.02% methyl red as a reporter of ROS in 0.5% agarose gel. The treatment applied with Ar/O₂ (1%) kINPen MED at 4 mm distance demonstrates that the penetration depth is directly proportional to the treatment time (unpublished/original data). (b) Proposed mechanisms of action of plasma ROS and concomitant effects in tissues. The primary effect is exerted in the first layers of cells that directly interact with the short-lived ROS. At this level, oxidative damage is induced in the extracellular matrix, cell membranes, and intracellular components of cells located in the outermost region of the tissue. The long-lived ROS able to penetrate into deeper regions of the tissue elicit a secondary oxidative effect in cells. However, the effect of plasma extends to more profound regions of the tissue due to the oxidation of redox-sensitive cysteine and thiols in proteins with paracrine effects and via cell-to-cell communication.

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