Cold plasma bullet influence on the water contact angle of human skin surface

Skin wettability is determinant factor for skin protection, adhesion to substances or patches, and molecule absorption, which are subsequently important for the overall health, the application of cosmetic formulation, as well as transdermal drug delivery. The present work is devoted to a novel way of human skin wettability enhancement by making use of atmospheric pressure helium plasma in the form of “bullets”. Although there exists extended bibliography as well as active research on both stratum corneum wettability and atmospheric pressure plasmas, their interacting relation had never been considered in the field of plasma biomedicine until recently. Herein, we demonstrate the chemical reactivity of helium plasma “bullets” produced by a sinusoidally driven reactor. It is demonstrated that their application to human stratum corneum yields hydrophilic skin surface. Water contact angle values as low as those reported following conventional treatments of skin, are obtained. The role of the reactive neutral and charged species in the stratum corneum modification is discussed, based on the experimental findings.