Bactericidal effect of surface plasma under different discharge modes

Abstract

Plasma-activated water (PAW) with reactive species produced by plasma in water can efficiently inactivate bacteria and has potential biomedical applications. Surface dielectric barrier discharge (SDBD) is extensively used for the preparation of PAW, and the bactericidal effects of PAW are highly related to the discharge mode. In previous studies, saline was directly placed under surface plasma within a short distance, and the gaseous reactive species diffused into the saline. In this study, the gaseous reactive species flowed into the saline by airflow, which was outside the treatment distance and accelerated the diffusion rate. The gaseous reactive species were compared at different power levels and flow rates, and three discharge modes were classified, namely, ozone, transition, and nitrogen oxides modes, based on the characteristic peaks in the spectra. Long-lived and short-lived species were detected in the saline, and short-lived species were more associated with the bactericidal effect. The results suggest that the bactericidal effect of the transition mode is the most prominent and the scavenger results show that nitric oxide (•NO), singlet oxygen, and peroxynitrite play a more crucial role in bacterial inactivation. This study provides a potential strategy for modulating the discharge mode to generate selective reactive species in plasma-activated saline to promote bactericidal application.

Plasma‐Activated Hydrogels for Microbial Disinfection

“…The discharge electric field was concentrated on both sides of the mesh electrode, resulting in the formation of a series of narrow discharge pulses, also known as filamentary discharges (Figure 1d). [ 49,50 ] Optical emission spectra (OES) were employed to determine reactive gaseous species in gaseous plasmas. Figure 1e shows the optical emission spectrum in the wavelength range from 200 to 800 nm, which is mainly composed of the first negative bands of N 2 + (B 2 $$\Sigma _u^ + $$ →X 2 $$\Sigma _g^ + $$), the second positive bands of N 2 (C 3 Π u →B 3 Π g ), and secondary diffraction of N 2 (C 3 Π u →B 3 Π g ).…”

Bactericidal effects of plasma‐activated saline prepared by surface dielectric barrier discharge with different dielectric layers and working gases

“…N 2 (A) and NO reacted with atomic oxygen to form NO and NO 2 , which were further oxidized to NO 3 and N 2 O 5 through R9-R12. [45,46]…”

“…N 2 (A) and NO reacted with atomic oxygen to form NO and NO 2 , which were further oxidized to NO 3 and N 2 O 5 through –. [ 45,46 ] $$${\rm{O}}+{\rm{O}}\to {}^{1}{\rm{O}}_{2},$$$ $$${{\rm{e}}+{\rm{O}}}_{2}\to {}^{1}{\rm{O}}_{2}+{\rm{e}},$$$ $$${{\rm{N}}}_{2}({\rm{A}})+{\rm{O}}\to \text{NO}+{\rm{N}},$$$ $$${\rm{O}}+\text{NO}+{\rm{M}}\to {\text{NO}}_{2}+{\rm{M}},$$$ $$${\text{NO}}_{2}{+{\rm{O}}}_{3}\to {\text{NO}}_{3}{+{\rm{O}}}_{2}\text{,}$$$ $$${\text{NO}}_{2}{+\text{NO}}_{3}\to {{\rm{N}}}_{2}{{\rm{O}}}_{5}.$$$…”

“…The previous study demonstrated that the bactericidal effects of PAS prepared by a tubular SDBD with the dielectric layer of quartz were eliminated in the presence of the scavengers for 1 O 2 and ONOO − . [ 46 ] Based on the weak DPCs formation by the treatment of the Quartz‐PAS, it is speculated that the reactive species including 1 O 2 and ONOO − in the Quartz‐PAS prefer to cause other damages of macromolecules, such as oxidatively modification of proteins, in the bacteria inactivation process (Figure 9). [ 26 ] The biological effects of the PTFE‐PAS may rely on the effects of fluorides and other reactive species, while that in Quartz‐PAS and Ceramic‐PAS were probably dependent on the ROS and RNS.…”

N2O5 in air discharge plasma: energy-efficient production, maintenance factors and sterilization effects

“…Furthermore, N 2 O 5 also exhibits promising prospects in plasma biomedicine. N 2 O 5 -rich gas and its treated water were reported to have potent disinfection effects in several previous studies [24,25]. Therefore, studying the role of N 2 O 5 in the sterilization of plasma effluent gas and plasma-activated water (PAW) is also necessary.…”