Analyzing the interactions between a DBD and skin components using Raman microspectroscopy

Abstract

Atmospheric pressure plasmas like dielectric barrier discharges (DBD) have shown noticeable positive effects on stimulation of wound healing, especially treatment of chronic wounds. Due to this, the therapeutic use of plasma devices is gaining importance although the interaction of plasma with skin and the processes taking place in skin are poorly understood.To get an insight into aforementioned interactions, a DBD, operating in air as process gas, is used for treatment of skin model components. DBD is characterized concerning plasma parameters and fluxes of important species like ozone or nitric oxide are determined. As a model component keratin was chosen because it is the most abundant protein in the stratum corneum, the upper layer of skin. After treatment, chemical changes of keratin are analyzed using Raman microspectroscopy. Raman spectroscopy is a non-destructive vibrational spectroscopic technique. It is capable of probing vibrational modes of functional groups of biological material. Hence, chemical changes of functional groups induced by plasma treatment will be detected.Chemical alterations in keratin are visible in the Raman spectrum already after a few seconds of treatment time. After longer treatment times a large oxidizing effect of the plasma generated reactive species is apparent which leads pH reduction after plasma treatment. Results achieved by this investigation contribute to the understanding of interaction between plasma and skin as well as wound healing mechanisms.