The human skin is a large (ca. 2 m2) membrane that separate regions with profoundly different properties. This implies that several simultaneous transport processes occur across a non-equilibrium system. The skin is a vital organ, and its outer layer, stratum corneum (SC) forms the barrier that prevents from desiccation and protects against the uptake of hazardous chemicals. SC also highly attractive as a target for directed and controlled delivery of drugs.

We aim at a characterization of the material properties of the SC by coupling macroscopic SC barrier properties to its molecular structure and dynamics. Diffusional transport across SC can be regulated by changes in the skin environments. One example is the abrupt increase in SC permeability at high degrees of SC hydration, called occlusion effect. Through a complementary experimental and theoretical approach, we have provided a molecular explanation to this effect, and the main principles are illustrated in the Figure.

We investigate how different classes of solvents and small molecules used as penetration enhancers or moisturizers influence the molecular properties of SC components and the macroscopic barrier properties of the skin. We also study the differences between healthy and diseased SC, focusing on psoriasis skin. We characterize the lipid and protein components in intact stratum corneum using natural abundance PT ssNMR, scattering and sorption techniques.