Insights into reactivity and bactericidal effects of water activated by He and Ar plasma jets

Abstract

Interactions of cold atmospheric-pressure plasma jets (APPJs) and water are important for water purification, chemical synthesis, medicine, and biotechnology. However, the reactivity and bactericidal effects of water activated with jets of different ionized gases remain unclear, especially in the commonly used helium (He)-and argon (Ar)-APPJ systems. Here, He and Ar are used as working gases to produce APPJ for comparing the plasma-induced aqueous reactive species and bacteria inactivation effects in solutions. Experimental results indicate that the Ar plasma jet shows a quicker propagation velocity and higher concentrations of gaseous reactive species, and the gas and electron temperature are different for the He and Ar plasma. Moreover, the higher concentration of aqueous reactive species, such as •OH, •O 2 − /ONOOH, H 2 O 2 , NO 2 − , and NO 3 − , and better bacterial inactivation effects are achieved by the Ar plasma treatment. Water deformation induced from plasma water is found as the reason for the different reactivity and bactericidal effects. Further validation experiments using a film with different pore diameters confirm that the molecular weight of the working gas influences the shape and stability of the cavity induced by the gas flow in the plasma jet, and plays a vital role in the production of aqueous reactive species with variable concentrations.

Catalyst-Free Activation and Fixation of Nitrogen by Laser-Induced Conversion

“…The peak at 746.5 nm was attributed to N plasma. , These results indicated that N 2 was ionized into a plasma state under laser irradiation. The peaks located at 656.3, 777.9, and 616.5 nm corresponded to H, O, and OH plasma, − indicating that H 2 O was also ionized into H, O, and OH plasma. The generation of these reactive species further validated the reaction mechanism of laser nitrogen fixation, involving the direct dissociation of nitrogen and water to produce a considerable amount of active species plasma.…”

Recent Developments in the Use of Plasma in Medical Applications

“…Plasma can also be used to directly manufacture biologically active solutions, and recent years have seen widespread investigation of plasma-activated water in the treatment of bacterial [117][118][119], fungal and viral infections [120,121]. Changes in plasma gas composition [117,119], plasma settings [118] or plasma sources [122] can dramatically alter the composition of the treated liquid, and this can give rise to changes in the physical properties of the activated liquid, which may in turn impact performance [123,124].…”

“…Plasma can also be used to directly manufacture biologically active solutions, and recent years have seen widespread investigation of plasma-activated water in the treatment of bacterial [117][118][119], fungal and viral infections [120,121]. Changes in plasma gas composition [117,119], plasma settings [118] or plasma sources [122] can dramatically alter the composition of the treated liquid, and this can give rise to changes in the physical properties of the activated liquid, which may in turn impact performance [123,124]. Other researchers continue to report on the significant impact of PAW and PAS on oncology, with numerous researchers describing the impact of varying the choice of liquid [125], liquid temperature [126] and plasma sources [123,[127][128][129][130], similar to those noted for antimicrobial applications.…”

Effect of air, O2, Ar, and N2 plasma‐activated water on mildewing activity of moldy pathogen of Gannan navel oranges

“…Low-temperature plasma is particularly suitable for microbial inactivation because it contains strong oxidizing hydroxyl radicals, excited nitrogen and oxygen atoms, and high-energy reactive particles, which interact with water molecules to produce reactive oxygen-nitrogen species (RONS), while plasma treatment of aqueous solutions produces plasma-activated water (PAW) containing RONS. [8][9][10][11] In recent years, PAW has become a hot research topic due to its pronounced bactericidal effect. PAW has good fluidity and can be used to overcome the limitations of conventional plasma treatments such as nonuniformity of treatment and the possibility of charged particles damaging the food surface.…”