|
Stratum Corneum Intercellular Lipid (SCL) plays a key role for the skin barrier function and investigation of its structure and function is crucial for the development of effective trans-dermal delivery of drugs and functional cosmetics. Primary constituents of SCL are simple equi-molar mixture of ceramides, fatty acids and cholesterol, though there are multiple varieties of ceramides, fatty acids involved. In order to avoid such complexity of components, there are several model SCLs proposed to investigate the mechanism of percutaneous penetration. Even though, development of simple but relevant model with structural and functional resemblance to the real SCL is still of great importance for the advancement of skin barrier research. Here we propose novel and simple method to prepare model SCL useful to investigate how materials or formulations are interact with skin. After screening of various ceramides and fatty acids with cholesterol, we have chosen equi-molar combination of ceramide3 with oleoyl group, stearic acid and cholesterol as a model SCL. To be an appropriate model to study barrier function, structural uniformity of lamellar layers in the sample is indispensable. After various trials to prepare layered SCL structures including traditional Bangham method for the liposome preparation, we have established novel method for the preparation of model SCL. That is simply to mix three components to melt at 120 °C as clear solution. After quenching to 80 °C, acetate buffer with pH 5.5 is added to be 20 wt% hydrated SCL which is a normal water content as natural stratum corneum (SC). Despite of such a simple preparation method, resulted sample showed highly desirable properties as a model SCL, namely structural characteristics similar to SC by SAXS and DSC analysis and uniformly layered lamellar structure by EM observation. By using this model, interaction and translocation of model SCL to or through SC can be analyzed.
|