Tracking plasma generated H₂O₂from gas into liquid phase and revealing its dominant impact on human skin cells

Abstract

The pathway of the biologically active molecule hydrogen peroxide (H 2 O 2 ) from the plasma generation in the gas phase by an atmospheric pressure argon plasma jet, to its transition into the liquid phase and finally to its inhibiting effect on human skin cells is investigated for different feed gas humidity settings. Gas phase diagnostics like Fourier transformed infrared spectroscopy and laser induced fluorescence spectroscopy on hydroxyl radicals ( • OH) are combined with liquid analytics such as chemical assays and electron paramagnetic resonance spectroscopy. Furthermore, the viability of human skin cells is measured by Alamar Blue ® assay. By comparing the gas phase results with chemical simulations in the far field, H 2 O 2 generation and destruction processes are clearly identified. The net production rate of H 2 O 2 in the gas phase is almost identical to the H 2 O 2 net production rate in the liquid phase. Moreover, by mimicking the H 2 O 2 generation of the plasma jet with the help of an H 2 O 2 bubbler it is concluded that the solubility of gas phase H 2 O 2 plays a major role in generating hydrogen peroxide in the liquid. Furthermore, it is shown that H 2 O 2 concentration correlates remarkably well with the cell viability. Other species in the liquid like • OH or superoxide anion radical (O •− 2 ) do not vary significantly with feed gas humidity.

Non-thermal Plasma Activates Human Keratinocytes by Stimulation of Antioxidant and Phase II Pathways

“…monocytes produce reactive species themselves (54). Moreover, the distribution of genes depicted in Venn diagrams clearly shows that the incubation time of plasma is much more important than the treatment time between 20 and 180 s. This finding supports the assumption that plasma-generated stable species in liquids induce the cellular response (55). Additionally, plasma-activated reactions were obtained up to several hours after plasma treatment in post-treatment kinetic measurements (56).…”

“…We concluded that only concentration-dependent differences were detected. Nevertheless, slight differences between reactions with plasma and those with H 2 O 2 in regard to KEAP1 expression are consistent with the fact that many other compounds (secondary radicals) in plasma interact with cells and provoke differences in their gene and protein expression (46,47,55).…”

Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

“…The important role of this effect was determined in a previous study for the same plasma source investigated here. 32 In this study, it was shown that plasma generated…”

Detection of HO2in an atmospheric pressure plasma jet using optical feedback cavity-enhanced absorption spectroscopy

“…Changing the composition of the curtain gas strongly influences the reactive component composition generated by the plasma. For instance, humidity variation controls the output of H 2 O 2 and OH [36]. The plasma jet is introduced into the cavity via a side opening.…”