Surface modification of stratum corneum for drug delivery and skin care by microplasma discharge treatment

Human skin is the largest organ and also the main barrier that prevents foreign substances from entering the body. The surface properties of the skin are relevant for transdermal drug delivery and cosmetics. Yucatan micropig skin is used as a substitute for human skin. A microplasma electrode is used for surface modification of the skin epidermal layer of the Yucatan micropig. Microplasma dielectric barrier discharge has a thin dielectric as a barrier (∼50 μm) and a frequency of 25 kHz. The surface properties of the epidermal layer were characterized by the measurement of the contact angle of the water droplet. The effects of different gases such as air, nitrogen, oxygen, helium or argon were compared. The change of the contact angle is temporal and it is returned to its initial state after several hours. Among the gases used for plasma ignition, oxygen and argon were the most effective for skin treatment. The distance of the skin from the electrode and the treatment time played a crucial roles in the increasing water contact angle. Changes of surface atomic concentration were determined by x-ray photoelectron spectroscopy. After microplasma treatment, the oxygen and nitrogen concentration increased at the skin surface.