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In the frame of BMBF project "BioLiP", new physical treatment techniques aiming at medical treatment of the human skin have been developed. The acronym BioLiP stands for "Desinfektion, Entkeimung und biologische Stimulation der Haut durch gesundheitsfördernde Licht-und Plasmaquellen" (Disinfection, germ reduction and biological stimulation of the human skin by health promoting light and plasma sources). A source applying a low-temperature dielectric barrier discharge plasma (DBD) has been investigated on its effectiveness for skin disinfection and stimulation of biological material. Alternatively an atmospheric plasma source consisting of a microwave resonator combined with a solid state power oscillator has been examined. This concept which allows for a compact and efficient design avoiding external microwave power supply and matching units has been optimized with respect to nitrogen monoxide (NO) production in high yields. In both cases various application possibilities in the medical and biological domain are opened up. Light sources in the visible spectral range have been investigated with respect to the proliferation of human cell types. Intensive highly selective blue light sources based on LED technology can slow down proliferation rates without inducing toxic effects which offers new opportunities for treatments of so-called hyperproliferative skin conditions (e.g. with psoriasis or in wound healing) using UV-free light.

The purpose of this article is to provide a sustainable dielectric barrier discharge for the treatment of living biological tissue. The investigation aims at the innocuousness of plasma treatment by DBD with biological tissue as counterelectrode on biomaterial. Instead of human tissue, pork and in vitro living epidermal human cells are used for the plasma treatment. Potential detrimental effects like current conduction, temperature, ozone and UV‐irradiation are investigated. All the levels are below the danger threshold. After plasma treatment of human cells, no cell damage could be detected. Hence applications on human beings with a DBD plasma source seems to be possible.

The inactivation of the Gram‐positive bacteria Staphylococcus epidermidis (ATCC 12228) in its vegetative state was studied in vitro after exposure to cold atmospheric pressure plasma generated by direct dielectric barrier discharge (DBD). Compared to UV radiation at 254 nm, plasma UV emission yielded no significant contribution to bacterial inactivation. Analysis of bacterial growth inhibition revealed a pH dependency on growth media. Yet, measurements combined with numerical simulations excluded the pH shift induced by plasma generated reactive species as the main cause of bacterial inactivation. Scanning electron microscopy (SEM) images showed no alteration of cell walls, while fluorescence microscopy revealed lethal damage to cell membranes even after 1 s treatment. When the cell membrane was already severely damaged, also degradation of the bacterial DNA by plasma treatment was found. We conclude that membrane damage due to reactive oxygen species (ROS) and DNA degradation are the main mechanisms of plasma‐induced bacterial death that is aggregated by milieu acidification.