Radical formation in skin and preclinical characterization of a novel medical plasma device for dermatology after single application

Cold atmospheric plasma (CAP) enables painless tissue treatment by producing reactive species including excited molecules and charged particles and is of great interest for medical applications. Medical CAP sources work in contact with air at ambient pressure, resulting in the generation of substantial amounts of reactive oxygen and nitrogen radicals. These radicals have a significant influence on cellular biochemistry, are crucial components of the immune system, and play a central role in wound therapy. CAP has a variety of applications, with a particular emphasis on tissue treatment in dermatology. It eradicates microorganisms by preventing biofilm formation so that wounds can be effectively disinfected and treated antiseptically. Using both in vitro and ex vivo methods, a comprehensive preclinical assessment of a novel battery-operated cold plasma handheld device with a reusable, and autoclavable glass cylinder was performed. The objectives were to evaluate the potential impact of single CAP application on radical formation with and without wound dressing, by directly measuring radicals in skin, to investigate the influence of CAP application on antimicrobial activity and cytotoxicity in vitro, and to assess skin tolerance ex vivo. The direct effect of CAP on the formation of radicals in the skin after plasma application at different levels with and without wound dressing was demonstrated quantitatively for the first time using electron paramagnetic resonance spectroscopy. Free radicals were measured in the skin as a function of the duration of CAP treatment. Furthermore, it was found that an alginate or wound plaster dressing does not significantly inhibit radical formation in skin compared to application without a dressing. In vitro and ex vivo data showed no cytotoxic potential with simultaneous efficacy against bacteria strains and no risk of temperature rise, pH change, skin barrier or DNA damage. These results show a high potential for wound healing applications in vivo.