[show abstract][hide abstract] ABSTRACT: Chemical characteristics and bactericidal properties of two low-temperature atmospheric-pressure Ar plasma devices are investigated: one of them with UV and the other with almost no UV on treated samples. The control of the UV radiation is achieved by two nozzles. One has a straight shape, and the other has a 90 degrees-bent. The bent nozzle blocks the light produced inside the torch, whilst allowing the plasma gas to reach the samples. The use of the straight nozzle allows the treatment by both the plasma gas and UV. We demonstrate that even an almost UV-free plasma treatment has bactericidal properties. Our measurements suggest that reactive species represent the main bactericidal factor of our low-temperature plasma.
[show abstract][hide abstract] ABSTRACT: Research on low-temperature atmospheric plasma sources (LTAPS) has grown strongly over the last few years, in part driven by possible medical 'in vivo' applications. LTAPS offer new technology for medicine and biomedical engineering. Important application examples include in situ production of reactive molecules and ions, delivery at the molecular level, contact-free and self-sterilizing devices. An important issue is the efficient bactericidal effect of LTAPS, which has already been studied widely in vitro. In spite of the many investigations, details of the plasma effect on bacteria are still largely unknown. To contribute to a better understanding of the sterilization process, we investigated the morphological changes of bacteria using atomic force microscopy before and after plasma treatment at high resolution. We examined both gram-positive and gram-negative bacteria at different plasma exposure times. Additionally, the effect of UV radiation as one agent in the plasma was investigated separately. Our results suggest that several sterilizing mechanisms exist and they proceed at different timescales.
New Journal of Physics 01/2009; · 4.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: Reactive oxygen and nitrogen species play important roles in regulation of pathophysiological processes in mammalian organisms. Chemical compounds releasing reactive species were shown to be effective for the chronic wound treatment. However, uncontrolled kinetic of the reactive species release and wound contamination with
byproducts of this reaction represent a problem for using such compounds for topical applications. The goal of our group is developing plasma devices for the controlled production of pharmacologically appropriate doses of reactive species for topical biomedical applications. An electric discharge generated by these devices causes dissociation of
the feed gas molecules into electrons, ions, and free radicals. In other words, gases are converted to plasma, the fourth state of mater. The composition of plasmas depends on the composition of feed gases, electric parameters of the discharge, and distance between the treatment area and the electrodes. Plasmas tested for the chronic wound treatment contain physiological (micromolar) concentrations of NO, NO2, OH, H2O2, and other reactive oxygen
species. The results of our in vitro experiments showed that these plasmas have significant bactericidal and bacteriostatic properties. Plasma irradiation has dosage-dependant effects on human cells including either induction or inhibition of cell proliferation and apoptosis. Our clinical studies showed a significant reduction of the bacterial load in the plasma-treated wounds in comparison with the untreated control wounds.
Free Radical Biology and Medicine, v.47, Suppl. 1, S129-S129 (2009).