Curvature-modulated Compositional and Dynamic Heterogeneity of Skin Lipid Structures

Daeyeon Lee

Stratum corneum (SC) is the outermost layer of the epidermis (the outermost layer of the skin) and serves an important barrier function by keeping molecules from passing into and out of the skin, thus protecting the lower layers of skin.  The organization of lipids in the intercellular regions of the SC is known to play a crucial role in determining the permeation properties of SC. The goal of this research project is to elucidate the effect of high curvature on the structure and properties of SC lipids. 

The curvature of lipid membranes is first controlled by creating lipid vesicles (liposomes) with different sizes. A polarity-sensitive fluorescence probe, Laurdan, was incorporated into the liposomes to probe the hydration level of lipid membranes. By measuring the generalized polarization of Laurdan for liposomes with different sizes, it is shown that liposomes with higher curvatures (thus smaller diameters) tend to have higher levels of hydration (lower GP). These results suggest that curvature may play an important role in determining the water permeability of SC lipid membranes.

Atomic force microscopy of SC lipid monolayer prepared by Langmuir-Blodgett technique shows that two coexisting phases are present at room temperature. We will investigate the effect of curvature on the phase behavior as well as the hydration of SC lipid membranes by creating supported lipid bilayers on surfaces with different corrugations presenting high curvature defects.

Phase-mode atomic force microscopy (AFM) image of three-component SC lipid monolayer created using Langmuir-Blodgett technique. Two coexisting phases can be observed.

Scheme showing the coexistence of two phases on planar substrate with no curvature; our aim is to deposit the same supported lipid bilayer onto surfaces with high curvature corrugations.