Abstract:Using a multi-gas plasma jet, we generated plasmas of various gas species such as argon, oxygen, nitrogen, carbon dioxide, and air. Photometric measurements of colorforming reactions were used to identify singlet oxygen, OH radicals, hydrogen peroxide, NO radicals, nitrite, and nitrate, which are important sterilization agents that are generated in the liquid phase. Oxygen plasma generated the largest amount of singlet oxygen, OH radicals, and hydrogen peroxide. Air plasma generated NO radicals, nitrite, and n… Show more
“…This result suggests the formation of reactive nitrogen compounds such as nitrous acid, nitric acid and peroxynitrous acid 59–62 . Nitrous acid, which is in acidic equilibrium with nitrite, may decompose in acidic medium into nitric oxide and nitrogen dioxide (Reactions 2 and 3) 58 . It is also known that nitrite is not stable under acidic conditions.Figure 9Variation of pH in water after He plasma treatment at various exposure time.
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In order to identify aqueous species formed in Plasma activated media (PAM), quantitative investigations of reactive oxygen and nitrogen species (ROS, RNS) were performed and compared to Milli-Q water and culture media without and with Fetal Calf Serum. Electron paramagnetic resonance, fluorometric and colorimetric analysis were used to identify and quantify free radicals generated by helium plasma jet in these liquids. Results clearly show the formation of ROS such as hydroxyl radical, superoxide anion radical and singlet oxygen in order of the micromolar range of concentrations. Nitric oxide, hydrogen peroxide and nitrite-nitrate anions (in range of several hundred micromolars) are the major species observed in PAM. The composition of the medium has a major impact on the pH of the solution during plasma treatment, on the stability of the different RONS that are produced and on their reactivity with biomolecules. To emphasize the interactions of plasma with a complex medium, amino acid degradation by means of mass spectrometry was also investigated using methionine, tyrosine, tryptophan and arginine. All of these components such as long lifetime RONS and oxidized biological compounds may contribute to the cytotoxic effect of PAM. This study provides mechanistic insights into the mechanisms involved in cell death after treatment with PAM.
“…This result suggests the formation of reactive nitrogen compounds such as nitrous acid, nitric acid and peroxynitrous acid 59–62 . Nitrous acid, which is in acidic equilibrium with nitrite, may decompose in acidic medium into nitric oxide and nitrogen dioxide (Reactions 2 and 3) 58 . It is also known that nitrite is not stable under acidic conditions.Figure 9Variation of pH in water after He plasma treatment at various exposure time.
…”
In order to identify aqueous species formed in Plasma activated media (PAM), quantitative investigations of reactive oxygen and nitrogen species (ROS, RNS) were performed and compared to Milli-Q water and culture media without and with Fetal Calf Serum. Electron paramagnetic resonance, fluorometric and colorimetric analysis were used to identify and quantify free radicals generated by helium plasma jet in these liquids. Results clearly show the formation of ROS such as hydroxyl radical, superoxide anion radical and singlet oxygen in order of the micromolar range of concentrations. Nitric oxide, hydrogen peroxide and nitrite-nitrate anions (in range of several hundred micromolars) are the major species observed in PAM. The composition of the medium has a major impact on the pH of the solution during plasma treatment, on the stability of the different RONS that are produced and on their reactivity with biomolecules. To emphasize the interactions of plasma with a complex medium, amino acid degradation by means of mass spectrometry was also investigated using methionine, tyrosine, tryptophan and arginine. All of these components such as long lifetime RONS and oxidized biological compounds may contribute to the cytotoxic effect of PAM. This study provides mechanistic insights into the mechanisms involved in cell death after treatment with PAM.
“…This highly effective plasma source generates a variety of potential applications in the food industry. Plasmas not only decontaminate surfaces but liquids as well . In the manufacturing process, plasmas can also remove allergens from surfaces and reduce enzymatic activities on food that otherwise impact the food's sensorial or nutritional quality .…”
Section: Decontamination Of Surfaces and Liquidsmentioning
Cold physical plasmas ignited a technological spark in industry, biotechnology, and medicine. Especially the field of hygiene benefited of the plasma's exceptional activity against pathogenic microorganisms. Together with plasma-based surface functionalization, these qualities are highly relevant in a variety of processes in health care, such as the decontamination or sterilization of medical devices, food, packaging materials, waste water, or indoor air. In medicine, plasma has proven to show promising antiseptic results on skin and mucosal membranes in infection-related diseases in dermatology and dentistry. This comprehensive review will discuss the current applications of cold plasma in the fields of hygiene, and will provide a promising outlook on many applications yet to come.
“…Its potential applications, such as material surface hydrophilization, 24 gas chromatography detection, 25 sterilization, 26 and ambient desorption/ionization mass spectrometry, 27,28 have been studied. Here, microplasma was utilized as an excitation source for droplet sample analysis.…”
Regenerative medicine and environmental science require the analysis of ultrasmall samples such as cells and nanoparticles. Therefore, a microplasma atomic emission spectroscopy (AES) system was developed in this study. This system combined microdroplet injection, which can introduce a small droplet of a few tens of picoliters into a plasma excitation/ionization source, with a microhollow cathode plasma source exhibiting a volume of a few microliters. When a 14 pL droplet of 100 mg L À1 sodium solution was introduced into an 8 W DC microplasma, no emission was observed possibly because of an insufficient excitation of the sample at low plasma gas temperature. Therefore, a pulsed discharge, producing highintensity electric input power, was implemented to give a pulse-synchronized microplasma AES system.A 15 ms pulsed power reaching a maximum value of 100 kW was obtained using a laboratory-built highintensity pulsed power supply and was applied to generate the plasma. This system achieved an excitation temperature of 7000 K, exceeding that of the common inductively coupled plasma. Pulsed plasma generation and sample droplet introduction into the plasma were synchronized to provide a high-sensitivity AES analysis. To this end, the time interval before the end of the generation and the beginning of the pulsed plasma generation was adjusted using a delay circuit. The optimal delay amounted to 40 ms. A droplet comprising Na, Ca, Mg, and K at 100 mg L À1 was analyzed using this system and the limits of detection equaled 300, 50, 30, and 640 fg for these analytes, respectively.
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