Preparation of a New Oligolamellar Stratum Corneum Lipid Model.

In this study, we present a preparation method for a new stratum corneum (SC) model system, which is closer to natural SC than the commonly used multilayer models. The complex setup of the native SC lipid matrix was mimicked by a ternary lipid mixture of ceramide [AP], cholesterol, and stearic acid. A spin coating procedure was applied to realize oligo-layered samples. The influence of lipid concentration, rotation speed, polyethylenimine, methanol content, cholesterol fraction, and annealing on the molecular arrangement of the new SC model was investigated by X-ray reflectivity measurements. The new oligo-SC model is closer to native SC in the total number of lipid membranes found between corneocytes. The reduction in thickness provides the opportunity to study the effects of drugs and/or hydrophilic penetration enhancers on the structure of SC in full detail by X-ray or neutron reflectivity. In addition, the oligo-lamellar systems allows one to infer not only the lamellar spacing, but also the total thickness of the oligo-SC model and changes thereof can be monitored. This improvement is most helpful for the understanding of transdermal drug administration on the nanoscale. The results are compared to the commonly used multilamellar lipid model systems and advantages and disadvantages of both models are discussed.