Coupled Antibacterial Effects of Plasma-Activated Water and Pulsed Electric Field

In the biomedical applications of cold plasma, the dominant biological effect is most typically attributed to the reactive oxygen and nitrogen species (RONS), while the physical effect of electric fields is sometimes overlooked. Here, we investigated the antibacterial effect of RONS in plasma-activated water (PAW) on the inactivation of E. coli bacteria, coupled with a mild 200-nanosecond pulsed electric field (PEF) treatment. By using transient spark discharge plasma in open atmospheric air and closed air reactors, and by adding hydrogen peroxide (H2O2) into the PAW, different chemical compositions of RONS were obtained. We measured the time evolution of the concentrations of key species in the PAW post-discharge: nitrites (NO2−) and H2O2. PAW rich in both NO2− and H2O2 showed an antibacterial effect, which was enhanced by the PEF, whereas PAW rich in NO2− and poor in H2O2 showed an enhancement of the antibacterial effect by the PEF only when H2O2 was externally added. The presence of sufficient concentrations of both NO2− and H2O2 optimized the formation of peroxynitrous acid (ONOOH), which caused a strong peroxidation of the cell membranes leading to the cell death, but it also made them more vulnerable to the PEF treatment. The results suggest that the interaction with radicals during the bacteria exposure to PAW leads to an antibacterial effect reinforced by the pulsed electric field, hence showing a synergy of the chemical and physical plasma agents. This opens new perspectives for applications both plasma and PEF areas of research

Important parameters in plasma jets for the production of RONS in liquids for plasma medicine: A brief review

Reactive oxygen and nitrogen species (RONS) are among the key factors in plasma medicine. They are generated by atmospheric plasmas in biological fluids, living tissues and in a variety of liquids. This ability of plasmas to create a delicate mix of RONS in liquids has been used to design remote or indirect treatments for oncological therapy by treating biological fluids by plasmas and putting them in contact with the tumour. Documented effects include selective cancer cell toxicity, even though the exact mechanisms involved are still under investigation. However, the “right” dose for suitable therapeutical activity is crucial and still under debate. The wide variety of plasma sources hampers comparisons. This review focuses on atmospheric pressure plasma jets as the most studied plasma devices in plasma medicine and compiles the conditions employed to generate RONS in relevant liquids and the concentration ranges obtained. The concentrations of H2O2, NO2-, NO3- and short-lived oxygen species are compared critically to provide a useful overview for the readerPeer ReviewedPostprint (author's final draft

Plasma and Aerosols: Challenges, Opportunities and Perspectives

The interaction of plasmas and liquid aerosols offers special advantages and opens new perspectives for plasma\u2013liquid applications. The paper focuses on the key research challenges and potential of plasma-aerosol interaction at atmospheric pressure in several fields, outlining opportunities and benefits in terms of process tuning and throughputs. After a short overview of the recent achievements in plasma\u2013liquid field, the possible application benefits from aerosol injection in combination with plasma discharge are listed and discussed. Since the nature of the chemicophysical plasma-droplet interactions is still unclear, a multidisciplinary approach is recommended to overcome the current lack of knowledge and to open the plasma communities to scientists from other fields, already active in biphasic systems diagnostic. In this perspective, a better understanding of the high chemical reactivity of gas\u2013liquid reactions will bring new opportunities for plasma assisted in-situ and on-demand reactive species production and material processing

Plasma-liquid interactions: a review and roadmap

Plasma-liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas

Effects of Non-Thermal Plasma on Yeast Saccharomyces cerevisiae

Cold plasmas generated by various electrical discharges can affect cell physiology or induce cell damage that may often result in the loss of viability. Many cold plasma-based technologies have emerged in recent years that are aimed at manipulating the cells within various environments or tissues. These include inactivation of microorganisms for the purpose of sterilization, food processing, induction of seeds germination, but also the treatment of cells in the therapy. Mechanisms that underlie the plasma-cell interactions are, however, still poorly understood. Dissection of cellular pathways or structures affected by plasma using simple eukaryotic models is therefore desirable. Yeast Saccharomyces cerevisiae is a traditional model organism with unprecedented impact on our knowledge of processes in eukaryotic cells. As such, it had been also employed in studies of plasma-cell interactions. This review focuses on the effects of cold plasma on yeast cells

LES DECHARGES ELECTRIQUES CONTINUES ET TRANSITOIRES, INDUITES PAR STREAMER, SOUS PRESSION ATMOSPHERIQUE, POUR LA DESTRUCTION DES COMPOSES ORGANIQUES VOLATILS (COV)

ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Decontamination of Escherichia coli biofilm by positive and negative DC corona discharge in air

International audienc

Decontamination of Streptococci biofilms and Bacillus cereus spores on plastic surfaces with DC and pulsed corona discharges

Cold air plasmas of DC and pulsed corona discharges: positive streamers and negative Trichel pulses were used for bio-decontamination of Streptococci biofilm and Bacillus cereus spores on polypropylene plastic surfaces. The reduction of bacterial population (evaluated as log10) in the biofilm on plastic surfaces treated by DC corona reached 2.4 logs with 10 min treatment time and 3.3 logs with 2 min treatment time with water spraying. The enhancement of plasma biocidal effects on the biofilm by electro-spraying of water through a hollow needle high-voltage electrode was investigated. No significant polarity effect was found with DC corona. Pulsed corona was demonstrated slightly more bactericidal for spores, especially in the negative polarity where the bacterial population reduction reached up to 2.2 logs at 10 min exposure time

Escherichia coli biofilm decontamination by air DC corona discharges

International audienc