Combining experimental and modelling approaches to study the sources of reactive species induced in water by the COST RF plasma jet

Abstract

The vast biomedical potential of cold atmospheric pressure plasmas (CAPs) is governed by the formation of reactive species. These biologically active species are formed upon the interaction of CAPs with the surroundings. In biological milieu, water plays an essential role. The development of biomedical CAPs thus requires understanding of the sources of the reactive species in aqueous media exposed to the plasma. This is especially important in case of the COST RF plasma jet, which is developed as a reference microplasma system. In this work, we investigated the formation of the OH radicals, H atoms and HO in aqueous solutions exposed to the COST plasma jet. This was done by combining experimental and modelling approaches. The liquid phase species were analysed using UV-Vis spectroscopy and spin trapping with hydrogen isotopes and electron paramagnetic resonance (EPR) spectroscopy. The discrimination between the species formed from the liquid phase and the gas phase molecules was performed by EPR and H-NMR analyses of the liquid samples. The concentrations of the reactive species in the gas phase plasma were obtained using a zero-dimensional (0D) chemical kinetics computational model. A three-dimensional (3D) fluid dynamics model was developed to provide information on the induced humidity in the plasma effluent. The comparison of the experimentally obtained trends for the formation of the species as a function of the feed gas and effluent humidity with the modelling results suggest that all reactive species detected in our system are mostly formed in the gas phase plasma inside the COST jet, with minor amounts arising from the plasma effluent humidity.

Non‐Thermal Plasma as a Unique Delivery System of Short‐Lived Reactive Oxygen and Nitrogen Species for Immunogenic Cell Death in Melanoma Cells

“…Simulations were performed using hyperfine values obtained from the literature in the Spin Trab Database (National Institute of Environmental Health Sciences, 2018). EPR calibration was performed using solutions of 4‐hydroxy‐TEMPO (Sigma‐Aldrich, 97%, 176141) as reported elsewhere . Specific spin traps and other molecules were used to detect RONS in the liquid ( Table 2 ).…”

Applications of the COST Plasma Jet: More than a Reference Standard

“…In the effluent, these non-charged species further interact with each other and the components of air. Since the high energy species are absent in the COST jet effluent, virtually no new reactive species are formed from the air and H 2 O vapour [48].…”

Ar(1s5) absolute radial densities in a ns‐pulsed argon plasma jet impinging on dielectric targets at floating potential – plasma action on organic molecules

“…During the last 15 years, Atmospheric Pressure Plasma Jets (APPJs) in the form of Guided Streamers (GSs) have been widely studied by many groups. APPJs can be obtained through the excitation/ionization of a noble gas (usually argon or helium) by means of rf, kHz‐sinusoidal and ‐pulsed high voltages (HV) . Besides, they exhibit interesting properties for applications in biomedicine, agriculture, and interactions with inert targets .…”

“…APPJs can be obtained through the excitation/ionization of a noble gas (usually argon or helium) by means of rf, kHz‐sinusoidal and ‐pulsed high voltages (HV) . Besides, they exhibit interesting properties for applications in biomedicine, agriculture, and interactions with inert targets . In the latter applications, the plasma impinges on different liquid and solid surfaces.…”

“…Besides, they exhibit interesting properties for applications in biomedicine, agriculture, and interactions with inert targets . In the latter applications, the plasma impinges on different liquid and solid surfaces. In most cases, there is a bilateral interaction between APPJs and exposed targets.…”