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Author: Bekeschus, Sander × Author: Bruno, Giuliana × Author: Weltmann, Klaus-Dieter × Author: Wende, Kristian × Start date: 2020 ×

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    On a heavy path – determining cold plasma-derived short-lived species chemistry using isotopic labelling
    (London : RSC Publishing, 2020) Wende, Kristian; Bruno, Giuliana; Lalk, Michael; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Bekeschus, Sander; Lackmann, Jan-Wilm
    Cold atmospheric plasmas (CAPs) are promising medical tools and are currently applied in dermatology and epithelial cancers. While understanding of the biomedical effects is already substantial, knowledge on the contribution of individual ROS and RNS and the mode of activation of biochemical pathways is insufficient. Especially the formation and transport of short-lived reactive species in liquids remain elusive, a situation shared with other approaches involving redox processes such as photodynamic therapy. Here, the contribution of plasma-generated reactive oxygen species (ROS) in plasma liquid chemistry was determined by labeling these via admixing heavy oxygen 18O2 to the feed gas or by using heavy water H218O as a solvent for the bait molecule. The inclusion of heavy or light oxygen atoms by the labeled ROS into the different cysteine products was determined by mass spectrometry. While products like cysteine sulfonic acid incorporated nearly exclusively gas phase-derived oxygen species (atomic oxygen and/or singlet oxygen), a significant contribution of liquid phase-derived species (OH radicals) was observed for cysteine-S-sulfonate. The role, origin, and reaction mechanisms of short-lived species, namely hydroxyl radicals, singlet oxygen, and atomic oxygen, are discussed. Interactions of these species both with the target cysteine molecule as well as the interphase and the liquid bulk are taken into consideration to shed light onto several reaction pathways resulting in observed isotopic oxygen incorporation. These studies give valuable insight into underlying plasma–liquid interaction processes and are a first step to understand these interaction processes between the gas and liquid phase on a molecular level.
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    Development of an electrochemical sensor for in-situ monitoring of reactive species produced by cold physical plasma
    (Amsterdam [u.a.] : Elsevier Science, 2021) Nasri, Zahra; Bruno, Giuliana; Bekeschus, Sander; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Wende, Kristian
    The extent of clinical applications of oxidative stress-based therapies such as photodynamic therapy (PDT) or respiratory chain disruptors are increasing rapidly, with cold physical plasma (CPP) emerging as a further option. According to the current knowledge, the biological effects of CPP base on reactive oxygen and nitrogen species (RONS) relevant in cell signaling. To monitor the safety and the biological impact of the CPP, determining the local generation of RONS in the same environment in which they are going to be applied is desirable. Here, for the first time, the development of an electrochemical sensor for the simple, quick, and parallel determination of plasma-generated reactive species is described. The proposed sensor consists of a toluidine blue redox system that is covalently attached to a gold electrode surface. By recording chronoamperometry at different potentials, it is possible to follow the in-situ production of the main long-lived reactive oxygen and nitrogen species like hydrogen peroxide, nitrite, hypochlorite, and chloramine with time. The applicability of this electrochemical sensor for the in-situ assessment of reactive species in redox-based therapies is demonstrated by the precise analysis of hydrogen peroxide dynamics in the presence of blood cancer cells.