Cold Plasma Microjet Research Articles

Assessment of the Physicochemical Properties and Biological Effects of Water Activated by Non‐thermal Plasma Above and Beneath the Water Surface

A direct current atmospheric pressure cold plasma microjet (PMJ) was used to produce plasma activated water (PAW) in two generation modes above (PAW‐A) and beneath (PAW‐B) the water surface. The physicochemical characteristics and biological effects of them were measured respectively. Results showed that PAW‐B exhibited stronger disinfection efficiency than PAW‐A, which was associated with ORP and conductivity, but not pH value, temperature, H2O2, NO3− or NO2−. Furthermore, the cell membrane integrity and membrane potential of S. aureus were destroyed more severely by PAW‐B. More importantly, a significant increase of intracellular ROS was induced by PAW‐B, which was supposed to contribute most to the sterilization. This work provides valuable guidance for the production and wide applications of PAW.

A study of oxidative stress induced by non-thermal plasma-activated water for bacterial damage

Ar/O2 (2%) cold plasma microjet was used to create plasma-activated water (PAW). The disinfection efficacy of PAW against Staphylococcus aureus showed that PAW can effectively disinfect bacteria. Optical emission spectra and oxidation reduction potential results demonstrated the inactivation is attributed to oxidative stress induced by reactive oxygen species in PAW. Moreover, the results of X-ray photoelectron spectroscopy, atomic absorption spectrometry, and transmission electron microscopy suggested that the chemical state of cell surface, the integrity of cell membrane, as well as the cell internal components and structure were damaged by the oxidative stress.

Atmospheric-pressure cold plasma treatment of contaminated fresh fruit and vegetable slices: inactivation and physiochemical properties evaluation

A direct-current, atmospheric-pressure air cold plasma microjet (PMJ) was applied to disinfect Salmonella directly deposited on fresh fruit and vegetable slices. Effective inactivation was achieved on sliced fruit and vegetables after 1 s plasma treatment. The physiochemical properties of the slices, such as water content, color parameters, and nutritional content were monitored before and after plasma treatment. It was found that the physiochemical properties changes caused by the plasma were within an acceptable range. Reactive oxygen species, which are believed to be the major bactericidal agents in the plasma, were detected by electron spin resonance spectroscopy and optical emission spectroscopy.

Inactivation of Staphylococcus aureus in Water by a Cold, He/O2 Atmospheric Pressure Plasma Microjet

AbstractA direct‐current, atmospheric pressure, cold plasma microjet (PMJ) sustained in a quasi‐steady gas cavity in liquid was used to inactivate Staphylococcus aureus suspended in distilled water. While helium gas (with 2% O2 as additive) was used as working gas, an effective inactivation (>99%) was achieved in 6 min. The inactivation of bacteria was further verified by surface morphology examination and LIVE/DEAD Baclight bacterial viability test (fluorescence microscopy). The overall pH and temperature of the liquid were monitored during the plasma treatment and were found to be below the critical values for the survival of S. aureus. Hydroxyl radical (•OH) was detected via electron spin resonance (ESR) spectroscopy, and alongside other intermediate reactive species, is attributed to the effective inactivation of S. aureus. End‐on optical emission spectroscopy show strong atomic oxygen emission both in air and in water.magnified image

Atmospheric pressure cold plasma as an antifungal therapy

A microhollow cathode based, direct-current, atmospheric pressure, He/O2 (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

A Novel Method of Tooth Whitening Using Cold Plasma Microjet Driven by Direct Current in Atmospheric-Pressure Air

We reported in this paper the tooth-whitening effect by a direct-current cold atmospheric-pressure air plasma microjet (PMJ) and saline solution (0.9%). All teeth were randomly divided into three groups, treated for 20 min with an air blow and saline solution, a PMJ and saline solution, and 35% hydrogen peroxide gel, respectively. Compared with the other groups, the teeth treated with the PMJ and saline solution showed the best tooth-whitening effect. The microhardness of the tooth enamel measurement showed no apparent differences among the three groups. A minor enamel surface morphological change was observed via SEM but was considered acceptable. Singlet oxygen ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) and hydroxyl (*OH) radicals were detected by electron spin resonance spectroscopy. Atomic oxygen (O) was observed in the optical emission spectra of the PMJ. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , *OH, and O were considered to be the key agents during the tooth-whitening process. This novel method of tooth whitening has the potential to revolutionize the clinical tooth-whitening procedure.