Effects of nonthermal plasma jet irradiation on the selective production of H2O2 and NO2− in liquid water

Abstract

We present the effects of the application of a nonthermal plasma jet to a liquid surface on H2O2 and NO2− generation in the liquid. Two distinct plasma irradiation conditions, with plasma contact and with no observable plasma contact with the liquid surface, were precisely compared. When the plasma was made to touch the liquid surface, the H2O2 concentration of the plasma-treated water was much higher than the NO2− concentration. In contrast, when no observable contact of the plasma with the liquid surface occurred, the ratio of the NO2− to H2O2 concentration became over 1 and NO2− became more dominant than H2O2 in the plasma-treated water. Our experiments clearly show that reactive oxygen and nitrogen species can be selectively produced in liquid using appropriate plasma-irradiation conditions of the liquid surface. The ratio of NO2− to H2O2 was controlled within a wide range of 0.02–1.2 simply by changing the plasma-irradiation distance from the liquid surface.

Time Behaviour of Helium Atmospheric Pressure Plasma Jet Electrical and Optical Parameters

“…The total transported charge agrees very well with similar experimental observations of the actual charge deposited on a liquid or solid target [31,32]. The average values of power dissipated during the plasma jet development for a single current pulse are of watt order, for all parameters studied here, while the energy dissipated during a single current pulse is of few tens of microjoules order.…”

Tailoring the Chemistry of Plasma-Activated Water Using a DC-Pulse-Driven Non-Thermal Atmospheric-Pressure Helium Plasma Jet

“…Overall, the data presented in this study highlight the opportunity of being able to tune the PAW chemistry by alteration of the polarity and pulse width of a plasma jet. In previous studies, other parameters that have been shown to significantly impact the PAW chemistry include the process gas [34], surrounding gas [19][20][21]23,43], and treatment distance [22,33,44]. By considering all of these parameters, it should be possible to fine-tune each of the processing parameters in order to achieve precise control over the PAW chemistry.…”

“…When a plasma jet is aimed at a water surface, the RONS in the plasma effluent of the flowing gas can dissolve into the water and participate in chemical reactions or interact with biological molecules and micro-organisms. It is particularly important to control the plasma jet-ambient air interactions because, during these interactions, the plasma jet activates oxygen and nitrogen molecules in the air, which subsequently dissolve in the water and are thought to have a major role in influencing the final PAW chemistry [19][20][21][22][23]. In order to obtain control over these plasma jet-air interactions, it is essential to develop methods of regulating (1) the ambient gases and (2) the main plasma species in the generation of PAW.…”

Dynamics of Singlet Oxygen-Triggered, RONS-Based Apoptosis Induction after Treatment of Tumor Cells with Cold Atmospheric Plasma or Plasma-Activated Medium

“…The gaseous and liquid phase of CAP contains electrons, photons, superoxide anions (O 2 ●− ), hydroperoxyl radicals (HO 2 ● ), hydrogen peroxide (H 2 O 2 ), hydroxyl radicals ( ● OH), atomic oxygen (O), singlet oxygen ( 1 O 2 ), ozone (O 3 ), nitric oxide ( ● NO), nitrogen dioxide ( ● NO 2 ), peroxynitrite (ONOO − ), nitrite (NO 2 − ), nitrate (NO 3 − ), dichloride radicals (Cl 2 ●− ) and hypochloride anions (OCl − ) 3,16,37,38 . Due to the high reactivity and short live time of most CAP-derived species, PAM (as well as other plasma-activated liquids) essentially contains only H 2 O 2 , NO 2 − and NO 3 − 33,39–41 . It is intriguing that a liquid with a RONS composition of such an apparently low complexity can trigger impressive antitumor effects in many tumor systems in vitro and in vivo , as shown by many groups 5,14,30,33–36,40,42–51 , and reviewed by Yan et al .…”