Correlations between gaseous and liquid phase chemistries induced by cold atmospheric plasmas in a physiological buffer

Abstract

The understanding of plasma-liquid interactions is of major importance, not only in physical chemistry, chemical engineering and polymer science, but in biomedicine as well as to better control the biological processes induced on/in biological samples by Cold Atmospheric Plasmas (CAPs). Moreover, plasma-air interactions have to be particularly considered since these CAPs propagate in the ambient air. Herein, we developed a helium-based CAP setup equipped with a shielding-gas device, which allows the control of plasma-air interactions. Thanks to this device, we obtained specific diffuse CAPs, with the ability to propagate along several centimetres in the ambient air at atmospheric pressure. Optical Emission Spectroscopy (OES) measurements were performed on these CAPs during their interaction with a liquid medium (phosphate-buffered saline PBS 10 mM, pH 7.4) giving valuable information about the induced chemistry as a function of the shielding gas composition (variable O2/(O2 + N2) ratio). Several excited species were detected including N2+(First Negative System, FNS), N2(Second Positive System, SPS) and HO˙ radical. The ratios between nitrogen/oxygen excited species strongly depend on the O2/(O2 + N2) ratio. The liquid chemistry developed after CAP treatment was investigated by combining electrochemical and UV-visible absorption spectroscopy methods. We detected and quantified stable oxygen and nitrogen species (H2O2, NO2-, NO3-) along with Reactive Nitrogen Species (RNS) such as the peroxynitrite anion ONOO-. It appears that the RNS/ROS (Reactive Oxygen Species) ratio in the treated liquid depends also on the shielding gas composition. Eventually, the composition of the surrounding environment of CAPs seems to be crucial for the induced plasma chemistry and consequently, for the liquid chemistry. All these results demonstrate clearly that for physical, chemical and biomedical applications, which are usually achieved in ambient air environments, it is necessary to realize an effective control of plasma-air interactions.

Inactivation efficacy and mechanisms of plasma activated water on bacteria in planktonic state

“…The factors that influence the bactericidal efficiency of PAW can be classified into three categories, that is, processing parameters, microbial characteristics and abiotic parameters. For processing parameters, applied voltage, plasma treatment time for PAW generation (Zhang et al 2017), exposure time of bacteria with PAW (Ursache et al 2014), treatment model (direct or indirect) (Han et al 2016a), feeding gases and air flow rate (Girard et al 2018;Machala et al 2018) should all be considered. Microbial parameters include the type and state of the micro-organism, for example, vegetative bacteria or spores, planktonic or detached state (Kamgang-Youbi et al 2008;Smet et al 2019), and the microbial community on food products may also affect the inactivation efficacy.…”

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.…”

Combinatorial Effect of Cold Atmosphere Plasma (CAP) and the Anticancer Drug Cisplatin on Oral Squamous Cell Cancer Therapy

“…Cold atmospheric plasma (CAP) has been extensively studied in the biomedical field in recent decades due to its biological and physicochemical properties [ 1 , 2 , 3 , 4 ]. Notably, CAP has recently been spotlighted in the local treatment of cancer because CAP in the biological system generates reactive oxygen species (ROS) and/or reactive nitrogen species (RNS), i.e., excessive ROS or RNS generation by CAP treatment induces oxidative stress against cancer cells and subsequently results in apoptotic death [ 5 , 6 , 7 , 8 ]. These unique properties of CAP are regarded as a safe treatment option for cancer patients because it can be applied to the specific body site of action without systemic side-effects against the human body [ 9 , 10 , 11 , 12 ].…”