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The reactivity of platinized ultramicroelectrodes (Pt‐black UMEs) towards superoxide anion O2.−, an unstable Reactive Oxygen Species (ROS), and its relatives, H2O2 and O2, was studied. Voltammetric studies in PBS demonstrate that Pt‐black UMEs provide: i) a well‐resolved reversible redox signature for O2.− detected in both alkaline and physiological buffers (pH 12 and 7.4); ii) irreversible oxidation and reduction waves for H2O2 at pH 7.4. The oxygen reduction reaction (ORR) at Pt‐black surfaces solely yields H2O2 (2 electrons/2 H+) at physiological pH. Consequently, Pt‐black UMEs allow to sense different ROS including superoxide anion for future biomedical or physico‐chemical investigations. [ABSTRACT FROM AUTHOR]

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 HOṖ 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. [ABSTRACT FROM AUTHOR]

Cold atmospheric pressure plasmas (CAPPs) are known to have bactericidal effects but the mechanism of their interaction with microorganisms remains poorly understood. In this study the bacteria Escherichia coli were used as a model and were exposed to CAPPs. Different gas compositions, helium with or without adjunctions of nitrogen or oxygen, were used. Our results indicated that CAPP induced bacterial death at decontamination levels depend on the duration, post-treatment storage and the gas mixture composition used for the treatment. The plasma containing O2 in the feeding gas was the most aggressive and showed faster bactericidal effects. Structural modifications of treated bacteria were observed, especially significant was membrane leakage and morphological changes. Oxidative stress caused by plasma treatment led to significant damage of E. coli. Biochemical analyses of bacterial macromolecules indicated massive intracellular protein oxidation. However, reactive oxygen and nitrogen species (RONS) are not the only actors involved in E. coli’s death, electrical field and charged particles could play a significant role especially for He-O2 CAPP. [ABSTRACT FROM AUTHOR]

Today, it is necessary to better understand the role of reactive species in plasmas on biological objects in order to use plasma processes for biomedical applications. Even when well-known plasma set-ups producing one main reactive species in a controlled environment are used, it is still difficult to understand reactive species interaction processes with biological systems. In this study, nanoimaging with the most sensitive mass spectrometry technology, and the use of isotopic 15N2 or/and 18O2 containing-Ar gas mixtures to produce the plasma is proposed in order to obtain isotopic and elemental data on microwave late afterglow treated Escherichia coli bacteria. By this way, new data dealing with reactive species binding processes on plasma treated bacteria by using NanoSIMS50 mass spectrometer are obtained. [ABSTRACT FROM AUTHOR]

This paper deals with atmospheric pressure DBDs driven under unipolar and bipolar pulsed excitation, in a con- text of chemical reactivity in flowing afterglow conditions. The resulting discharges in air and nitrogen are examined via electrical and optical diagnostics. Then, their yield in the production of active species (ozone for the air afterglow-atomic Nitrogen and N2 (A) metastables for the N2 afterglow) is compared. An effort is made to illustrate the key discharge parameters that are likely to influence the concentrations of neutral active species in afterglow conditions. [ABSTRACT FROM AUTHOR]

Compelling evidence suggests that Cold Atmospheric Pressure Plasma (CAPP) has potential as a new cancer therapy. However, knowledge about cellular signaling events and toxicity subsequent to plasma treatment is still poorly documented. The aim of this study was to focus on the interaction between 3 different types of plasma (He, He-O2, He-N2) and human epithelial cell lines to gain better insight into plasma-cell interaction. We provide evidence that reactive oxygen and nitrogen species (RONS) are inducing cell death by apoptosis and that the proteasome, a major intracellular proteolytic system which is important for tumor cell growth and survival, is a target of (He or He-N2) CAPP. However, RONS are not the only actors involved in cell death; electric field and charged particles could play a significant role especially for He-O2 CAPP. By differential label-free quantitative proteomic analysis we found that CAPP triggers antioxidant and cellular defense but is also affecting extracellular matrix in keratinocytes. Moreover, we found that malignant cells are more resistant to CAPP treatment than normal cells. Taken together, our findings provide insight into potential mechanisms of CAPP-induced proteasome inactivation and the cellular consequences of these events. [ABSTRACT FROM AUTHOR]

Cover: Superposed NanoSIMS‐AFM images showing enrichment in 18O, as indicated by orange‐red spots, coming directly from the discharge on the plasma treated bacteria deposited on a polycarbonate filter. 18O fixation on bacteria is high and not homogeneous in Ar‐N2‐O2 microwave afterglow. Further details can be found in the article by David Duday et. al. on page 864. [ABSTRACT FROM AUTHOR]