Analysis of Hydroxyl Radical and Hydrogen Peroxide Generated in Helium-Based Atmospheric-Pressure Plasma Jet and in Different Solutions Treated by Plasma for Bioapplications

Abstract

This study systematically analyzed reactive species generated with self-built helium-based low-temperature atmospheric-pressure plasma jet (He-APPJ); we measured the hydroxyl radical (·OH) and hydrogen peroxide (H2O2) above surfaces of plasma–treating solutions and in plasma-treated medium (PTM) of different solutions, including deionized water, phosphate buffered saline, and Dulbecco’s modified Eagle medium. The effects of adding O2 into He working gas on ·OH and H2O2 generation were discussed. The MCF7 cell responses to plasma treatment were also observed. The ·OH emission (309 nm) in He-APPJ and above surfaces of plasma–treating solutions were analyzed through optical emission spectroscopy, and concentrations of ·OH and H2O2 in different solutions were measured using terephthalic acid and Amplex Red, respectively. In our plasma system, it was observed that higher conductivity of solutions may cause stronger ·OH emission above solution. The ingredients of the solution may affect the concentrations of ·OH and H2O2. Addition of 0.1% O2 generates strongest ·OH emission above surfaces of plasma–treating solution with our He-APPJ, and thus, the highest H2O2 concentration in PTM. The MCF7 cell viability is influenced by the H2O2 concentration in PTM. The results of this study can facilitate further study of plasma effects on PTM and cell culture.

Plasma–Saline Water Interaction: A Systematic Review

“…In plasma jet treatments, most studies use He (99.996%) as carrier gas [ 44 , 46 , 47 ] or gas mixtures such as He + O 2 (99.996% He + 0.3 to 0.5% O 2 ) [ 39 , 51 ], as well as atmospheric air and N 2 (99.9%) [ 22 , 60 ].…”

“…On the other hand, an inverse relationship with salinity was observed, i.e., the higher the saline concentration, the lower the [H + ]. For PBS, the value of [H + ] is practically constant, since it is a buffered solution [ 22 , 39 , 40 , 60 ]. Because of this, we estimated the amount of H + ions produced by the plasma in the buffer through the Henderson–Hasselbalch equation (Equation (1)): …”

“…The production of these species grows with the increase of the energy of the species interacting with the surface of the solution, effective area of interaction, and treatment time. In saline water, the chlorine radical can reduce the concentration of NO 2 − and increase the pH of the reaction medium due to the occurrence of Equation (2) [ 21 , 39 , 48 , 51 ] as follows: HClO + NO 2 − → ClNO 2 + OH − …”

“…One of the consequences of the increase in conductivity caused by the plasma is the greater formation and emission of some active aqueous species, such as the •OH e H 2 O 2 [ 39 , 47 , 51 ]. However, the initial conductivity of the solution is a factor of similar importance for the species formation process, in different gas discharge configurations.…”

Effects of O2 Addition on the Discharge Parameters and Production of Reactive Species of a Transferred Atmospheric Pressure Plasma Jet

“…In recent years atmospheric pressure plasma jets (APPJs) produced in open environments have received a lot of attention, not only because of their versatility and ease of use, but also due to the encouraging results achieved in the most diverse applications [1][2][3][4][5]. Special attention has been given to medical and biological applications of APPJs, whose beneficial effects have been attributed to the reactive oxygen and nitrogen species (RONS) produced by the plasma jets [6][7][8]. The actions of the RONS are not only limited to biological materials, since they also contribute to the hydrophilization and surface activation processes of many materials treated with plasma [9,10].…”