Uta Schnabel

New Nonthermal Atmospheric-Pressure Plasma Sources for Decontamination of Human Extremities

The research and development of plasma sources, which can be used for therapeutic applications in the new and emerging field of plasma medicine, has gained more and more interest during recent years. These applications require cold nonthermal plasmas operating at atmospheric pressure. Due to the fact that, in general, plasma on or in the human body is a challenge both for medicine and plasma physics, basic research combining experimental physical and biological investigation and modeling is necessary to provide the required knowledge for therapeutic applications. It turned out that each application needs a special tailor-made plasma source, passing a minimum set of physical and biological tests before it can be considered for medical use. In addition to atmospheric-pressure plasma jets, dielectric barrier discharges offer great potential for a variety of medical indications. A new 2-D and even 3-D acting plasma source is introduced, exemplified for a possible decontamination of human extremities or similar tasks. In contradiction to most of todays existing plasma sources with fixed electrodes and nozzles, the prototype uses flexible electrodes to automatically adapt the plasma under equal and stable conditions to nearly all surface structures. First, physical and biological investigations demonstrate the general potential for therapeutic applications on preferably intact skin surfaces.

Deposition of Antimicrobial Copper-Rich Coatings on Polymers by Atmospheric Pressure Jet Plasmas

Inanimate surfaces serve as a permanent reservoir for infectious microorganisms, which is a growing problem in areas in everyday life. Coating of surfaces with inorganic antimicrobials, such as copper, can contribute to reduce the adherence and growth of microorganisms. The use of a DC operated air plasma jet for the deposition of copper thin films on acrylonitrile butadiene styrene (ABS) substrates is reported. ABS is a widespread material used in consumer applications, including hospitals. The influence of gas flow rate and input current on thin film characteristics and its bactericidal effect have been studied. Results from X-ray photoelectron spectroscopy (XPS) and atomic force microscopy confirmed the presence of thin copper layers on plasma-exposed ABS and the formation of copper particles with a size in the range from 20 to 100 nm, respectively. The bactericidal properties of the copper-coated surfaces were tested against Staphylococcus aureus. A reduction in growth by 93% compared with the attachment of bacteria on untreated samples was observed for coverage of the surface with 7 at. % copper.

Plasma based technologies for reprocessing of medical devices, endoscopes and catheters

Summary form only given. Medical endoscopes are most complex and expensive devices for intracorporeal diagnostic and surgery. A treatment with such a device always includes the risk of endoscopic associated nosocomial infections. A consequent infection prophylaxis mainly includes safe cleaning and sterilization methods for the endoscopes. Conventional used chemical gases are mostly toxic as well as carcinogenic and therefore special safety conditions have to be fulfilled. Furthermore, those agents lead to material damage and biocompatibility difficulties. Cold atmospheric pressure plasmas have a huge potential for the sterilization of such complex medical devices and therefore are of great scientific and hygienic interest.

Effects on cell viability, growth and morphology of C. albicans SC5314 biofilms after kINPen®09 plasma treatment

Microorganisms are predominantly organized in biofilms, where cells live in dense communities and are more resistant to external stresses compared to their planktonic counterparts. With in vitro experiments, the susceptibility of Candida albicans biofilms to a non-thermal plasma treatment (plasma source kINP®09), in terms of growth, survival, and cell viability was investigated. Behind that background, the C. albicans strain SC5314 (ATCC® MYA-2876™) was plasma treated for different time periods (30 s, 60 s, 120 s, 180 s, 300 s). The results of experiments embracing colony forming units, fluorescence LIVE/DEAD assays, and XTT assays revealed a negative influence of the plasma treatment on the proliferation ability, vitality, and the metabolism of C. albicans biofilms, respectively. Morphological analysis of plasma-treated biofilms using atomic force microscopy supported the indications for lethal plasma effects concomitant with membrane disruptions and the loss of intracellular fluid. Controversial to other publications, fluorescence- and confocal laser scanning-microscopic inspection of plasma-treated biofilms indicated, that an inactivation of cells mainly appeared on the bottom side of the biofilms. If this inactivation leads to a detachment of the biofilms from the overgrown surface, it might offer completely new approaches in the plasma treatment of biofilms. Because of its biochemical-mechanical mode of action, resistances of microbial cells against plasma are unknown at this state of research.

Application of a bifilar helix discharge in endoscope biopsy channels for plasma decontamination and biomedical aspects

In modern medicine endoscopes are essential diagnostic and therapeutic tools. Due to their complex geometry, the thermolability of the used materials and the integrated sensitive electronics only a few sterilization techniques are applicable for this high cost medical product, e.g. sterilization with ethylene oxide (ETO) or the low temperature steam sterilization with formaldehyde. However, these techniques use carcinogenic chemicals and therefore need long outgas-times or operate at low pressure, which is technically demanding. Furthermore, the long and narrow flexible tubes inside the endoscopes are challenging.