Radiation Driven Chemistry in Biomolecules—is (V)UV Involved in the Bioactivity of Argon Jet Plasmas?

Abstract

Cold physical plasmas, especially noble gas driven plasma jets, emit considerable amounts of ultraviolet radiation (UV). Given that a noble gas channel is present, even the energetic vacuum UV can reach the treated target. The relevance of UV radiation for antimicrobial effects is generally accepted. It remains to be clarified if this radiation is relevant for other biomedical application of plasmas, e.g., in wound care or cancer remediation. In this work, the role of (vacuum) ultraviolet radiation generated by the argon plasma jet kINPen for cysteine modifications was investigated in aqueous solutions and porcine skin. To differentiate the effects of photons of different wavelength and complete plasma discharge, a micro chamber equipped with a MgF2, Suprasil, or Borosilicate glass window was used. In liquid phase, plasma-derived VUV radiation was effective and led to the formation of cysteine oxidation products and molecule breakdown products, yielding sulfite, sulfate, and hydrogen sulfide. At the boundary layer, the impact of VUV photons led to water molecule photolysis and formation of hydroxyl radicals and hydrogen peroxide. In addition, photolytic cleavage of the weak carbon-sulfur bond initiated the formation of sulfur oxy ions. In the intact skin model, protein thiol modification was rare even if a VUV transparent MgF2 window was used. Presumably, the plasma-derived VUV radiation played a limited role since reactions at the boundary layer are less frequent and the dense biomolecules layers block it effectively, inhibiting significant penetration. This result further emphasizes the safety of physical plasmas in biomedical applications.

d-Glucose Oxidation by Cold Atmospheric Plasma-Induced Reactive Species

“…In this case, the assay detects predominantly • OH radicals generated from the photolysis of water by the argon excimer VUV traveling the noble gas channel to the gas–liquid interface. 19 Of note, the concentration of OH/O radicals in d -glucose solutions remained almost unchanged, seemingly contradicting reports on OH radical-driven oxidation of glucose (Amaniampong et al , 38 Rinsant et al. ( 73 )).…”

“…A tiny chamber equipped with a borofloat-33 window (25 mm × 1 mm, Nano Quarz Wafer GmbH) and MgF 2 window (25 mm × 1 mm, Korth Kristalle GmbH) were employed to determine the role of vacuum ultraviolet (VUV)/ultraviolet radiation (UV) irradiation by blocking the gas–liquid interface as reported. 19 …”

“…A 750 μL volume of aqueous glucose solution (2 mM) was placed in a 24 well-plate (Sarstedt, Germany) and treated from 1 to 10 min with a plasma jet nozzle to a liquid distance of 9 mm for all plasma treatments. A tiny chamber equipped with a borofloat-33 window (25 mm × 1 mm, Nano Quarz Wafer GmbH) and MgF 2 window (25 mm × 1 mm, Korth Kristalle GmbH) were employed to determine the role of vacuum ultraviolet (VUV)/ultraviolet radiation (UV) irradiation by blocking the gas–liquid interface as reported …”

“… 12 , 15 − 18 , In addition, auxiliary effects of (vacuum-) UV radiation and electromagnetic fields are discussed. 19 , 20 …”

“…To current knowledge, the interference of CAP-derived reactive oxygen and nitrogen species with cellular redox signaling processes triggers diverse downstream events on the biological level. , Among these, modulation of immune responses and changes in cell survival stand out. Determined by the individual design of a CAPs source and controlled by parameter variation, various short- and long-lived reactive species such as singlet oxygen ( 1 O 2 ), hydroxyl radical ( • OH), atomic oxygen [O­( 3 P)], superoxide anion radicals ( • O 2 – ), ozone (O 3 ), nitric oxides (N x O y ), and hydrogen peroxide (H 2 O 2 ) are generated alongside free electrons, and neutral particles (e.g., metastable argon (Ar), Ar*, Ar 2 , and N 2 ). ,− , In addition, auxiliary effects of (vacuum-) UV radiation and electromagnetic fields are discussed. , …”