On the wetting properties of human stratum corneum epidermidis surface exposed to cold atmospheric-pressure pulsed plasma

The Stratum corneum is the outermost layer of the skin, acting as a protective barrier of the epidermis, and its surface properties are directly related to the spreading of topically applied drugs and cosmetics. Numerous works have been devoted to the wettability of this layer over the past 70 years, but, despite the extensive application of atmospheric-pressure plasmas to dermatology, stratum corneum wettability with respect to plasma-induced species has never been considered. The present report assesses the treatment of human stratum corneum epidermidis by atmospheric-pressure pulsed cold plasma-jets for various time intervals and both chemical and morphological modifications are probed. The increase and saturation of the surface free energy due to functionalization are demonstrated, whereas prolonged treatment leads to tissue local disruption (tissue integrity is lost, and stratum corneum looks exfoliated, porous, and even thermally damaged). The latter point arises skepticism about the common practice...