The active role of organic molecules in the formation of long‐lived reactive oxygen and nitrogen species in plasma‐treated water solutions

Abstract

Plasma-treated water solutions (PTWS) allow the delivery of reactive oxygen and nitrogen species (RONS) to cells and tissues for different purposes. The mechanism of RONS formation has been clearly modelled in simple liquids like water, by assuming a plasma-driven process independent from the liquid. PTWS for biological experiments, however, are often produced from solutions of complex composition, where the formation mechanism of RONS is far from being understood. In this paper, we describe how water, phosphate-buffered saline solution and two cell culture media were plasma-treated in different conditions to demonstrate how the different composition of the liquids affects the formation of stable RONS (H 2 O 2 and NO 2 − ) in the resulting PTWS, especially when aromatic organic molecules are present.

Anticancer Effects of Plasma-Treated Water Solutions from Clinically Approved Infusion Liquids Supplemented with Organic Molecules

“…The results here reported are in agreement with our recent findings for PTWS from double-distilled water, which demonstrated that the H 2 O 2 generation in our processes (i.e., plasma not in contact with the liquid, closed chamber of the reaction) is promoted by the oxidation reactions of organic compounds with a phenolic ring, probably triggered by transient ROS like atomic oxygen and O 3 . Similar results were also obtained by Hefny et al, whose results demonstrate that the H 2 O 2 formation in deionized water is dependent on the presence of phenol in the liquid phase, in the absence of humidity in the plasma phase (i.e., negligible evaporation of water) .…”

“…The trend for NO 2 – in PT-SIII (Figure C) and in PT-SIII-tyr (Figure D) confirms that NO 2 – ions are formed in both liquids only after air-fed DBD treatments, at concentrations that increase with the treatment time. Conversely, after O 2 -fed-DBD, no nitrite ions could be detected in PT-SIII as well as in PT-SIII-tyr (Figure C,D), in agreement with our recent findings . We have recently demonstrated that the NO 2 – formation in PTWS is prevalently due to the RNS (presumably NO or NO 2 ) generated in the plasma.…”

“…Conversely, after O 2 -fed-DBD, no nitrite ions could be detected in PT-SIII as well as in PT-SIII-tyr (Figure 2C,D), in agreement with our recent findings. 26 We have recently demonstrated that the NO 2 − formation in PTWS is prevalently due to the RNS (presumably NO or NO 2 ) generated in the plasma. Therefore, the amount of NO 2 − ions in PTWS can be modulated by properly adjusting the proportion between O 2 and N 2 in the feed, and other parameters such as applied voltage and treatment time.…”

“…A detailed description of the DBD source is provided in ref . To plasma-treat the liquids, commercial TPP Petri dishes (57 mm diameter, Techno Plastic Products, Trasadingen, CH) were filled with 2 mL of the SIII solution and housed below the source using a slot on the flow unit.…”

Does non-thermal plasma modify biopolymers in solution? A chemical and mechanistic study for alginate

“…30–32 The same effect has been observed by other authors after treating cell culture media and amino acids solutions. 36 These effects are due to secondary reactions that take place in water solutions and that are likely initiated by the interaction of short-lived RONS during the direct NTP treatment with the organic matter.…”