Nitrosylation vs. oxidation – How to modulate cold physical plasmas for biological applications

Abstract

Thiol moieties are major targets for cold plasma-derived nitrogen and oxygen species, making CAPs convenient tools to modulate redox-signaling pathways in cells and tissues. The underlying biochemical pathways are currently under investigation but especially the role of CAP derived RNS is barely understood. Their potential role in protein thiol nitrosylation would be relevant in inflammatory processes such as wound healing and improving their specific production by CAP would allow for enhanced treatment options beyond the current application. The impact of a modified kINPen 09 argon plasma jet with nitrogen shielding on cysteine as a thiol-carrying model substance was investigated by FTIR spectroscopy and high-resolution mass spectrometry. The deposition of short-lived radical species was measured by electron paramagnetic resonance spectroscopy, long-lived species were quantified by ion chromatography (NO 2 - , NO 3 - ) and xylenol orange assay (H 2 O 2 ). Product profiles were compared to samples treated with the so-called COST jet, being introduced by a European COST initiative as a reference device, using both reference conditions as well as conditions adjusted to kINPen gas mixtures. While thiol oxidation was dominant under all tested conditions, an Ar + N 2 /O 2 gas compositions combined with a nitrogen curtain fostered nitric oxide deposition and the desired generation of S-nitrosocysteine. Interestingly, the COST-jet revealed significant differences in its chemical properties in comparison to the kINPen by showing a more stable production of RNS with different gas admixtures, indicating a different • NO production pathway. Taken together, results indicate various chemical properties of kINPen and COST-jet as well as highlight the potential of plasma tuning not only by gas admixtures alone but by adjusting the surrounding atmosphere as well.

On a heavy path – determining cold plasma-derived short-lived species chemistry using isotopic labelling

“…Besides pure argon, 1% oxygen (purity 4.8, Air Liquide, Ar/O 2 ) was used for the experiments as these conditions offered promising oxidative thiol modication potential. 53 The COST-jet 64 was powered by constant 300 mW at a frequency of 13.56 MHz. Total gas ux was kept constant at 1 slm of pure dry helium (5.0, Air Liquide) with 1% oxygen admixture (purity .8, Air Liquide, He/ O 2 ).…”

“…indicates a strongly oxidizing environment (oxygen in the feed gas, long treatments), whereas the presence of RSSR, RSO 2 H, or RSSO 3 H reveals weakly oxidizing conditions (short treatments, nitrogen shielded feed gas). 53 Here, this model was used to investigate transport processes at the interface between the gas phase (the effluent) and the target (cysteine solutions). To monitor such reactions, the chosen cysteine model with its multiple oxidation states of the thiol moiety seemed to be superior to the phenol model.…”

“…[48][49][50] Hence, CAP impact can yield to (non-enzymatic) post-translational modications (PTMs), with some of which transport signicant inuence in cellular signaling. [51][52][53][54] However, so far no specic member of the various ROS or RNS could be attributed to be the major driver of these reactions. One of the reasons is the limited knowledge that is present on plasma-derived liquid chemistry.…”

GSH Modification as a Marker for Plasma Source and Biological Response Comparison to Plasma Treatment

“…Helium and oxygen (grade 5) were used for the experiments. The COST-Jet was operated at the ignition voltage to be comparable to reported literature [11]. The plasma treatment parameters are listed in Table 1.…”

“…Investigations correlating the possible biological responses induced by plasma treatment to plasma parameters and components are typically limited to the source used. The configuration, discharge parameters, and environment influence the plasma components that interact with the cells and, thus, the contribution of each component to the cellular response [7][8][9][10][11]. However, direct cause-effect correlations have not yet been defined.…”