Analysis of reactive oxygen and nitrogen species generated in three liquid media by low temperature helium plasma jet

Abstract

In order to identify aqueous species formed in Plasma activated media (PAM), quantitative investigations of reactive oxygen and nitrogen species (ROS, RNS) were performed and compared to Milli-Q water and culture media without and with Fetal Calf Serum. Electron paramagnetic resonance, fluorometric and colorimetric analysis were used to identify and quantify free radicals generated by helium plasma jet in these liquids. Results clearly show the formation of ROS such as hydroxyl radical, superoxide anion radical and singlet oxygen in order of the micromolar range of concentrations. Nitric oxide, hydrogen peroxide and nitrite-nitrate anions (in range of several hundred micromolars) are the major species observed in PAM. The composition of the medium has a major impact on the pH of the solution during plasma treatment, on the stability of the different RONS that are produced and on their reactivity with biomolecules. To emphasize the interactions of plasma with a complex medium, amino acid degradation by means of mass spectrometry was also investigated using methionine, tyrosine, tryptophan and arginine. All of these components such as long lifetime RONS and oxidized biological compounds may contribute to the cytotoxic effect of PAM. This study provides mechanistic insights into the mechanisms involved in cell death after treatment with PAM.

Antibacterial effects of low-temperature plasma generated by atmospheric-pressure plasma jet are mediated by reactive oxygen species

“…It is well accepted that multiple types of ROS/RNS are generated from LTP treatments 26,29 . However, the location of formation of the reactive species, and their ability to diffuse into porous surfaces and the liquid media from the gaseous plasma phase for APPJ configurations has not been as clearly established.…”

“…However, the location of formation of the reactive species, and their ability to diffuse into porous surfaces and the liquid media from the gaseous plasma phase for APPJ configurations has not been as clearly established. Electron paramagnetic resonance spectroscopy and proton nuclear magnetic resonance analysis have revealed that more stable species such as hydrogen peroxide are largely formed within the tube of the plasma jet, and that more reactive and transient species such as hydroxyl and superoxide tend to form in the plasma stream outside of the tube and between the nozzle of the jet and the target sample 29 . Additionally, the amounts of different types of species generated as a function of various system parameters is also under investigation.…”

“…It has been shown that small amounts of UV radiation are emitted by LTP devices, but it is thought that the dose is not sufficient to cause damage to the targeted treatment sample and that the majority of the VUV photons (<180 nm) are absorbed into the air 29,38 . However, H 2 O 2 can absorb large amounts of UV energy at short wavelengths, resulting in its dissociation into highly reactive, antibacterial hydroxyl radicals 28,29,[39][40][41] . Therefore, it is possible that at the time of LTP treatment, far more potent, hydroxyl radicals are generated.…”

“…These results indicate that the bactericidal effects of the LTP treatments are mediated indirectly through the generation of labile bactericidal elements in the media, and that the PAM containing these mediators has bactericidal properties equivalent to that of direct LTP treatments. plasma can generate ROS/RNS in the presence of atmospheric oxygen and nitrogen 28,29 . Since our APPJ system incorporated gaseous oxygen into the carrier gas, and we observed the transient nature of the bactericidal mediators in PAM, we hypothesized that ROS/RNS may be generated in the media following LTP treatment and may be responsible for the killing of bacteria.…”

Effect of cold atmospheric plasmas on bacteria in liquid: The role of gas composition

“…Hence the interaction of atmospheric pressure plasmas with liquids was recently subject to a number of studies …”