The Importance of Stratum Corneum Lipid Organization for Proper Barrier Function

The intercellular lipid membranes of the SC are an excellent biological example for the relationship between the lipid composition, its physicochemical properties, and biological function. This chapter aims to review the recent investigations of the nanostructure of the stratum corneum lipid membranes, as they are known to play a key role for the barrier function of the skin. The focus of current researches is primarily placed on the investigation of the impact of the different lipid subspecies, in particular the various ceramide subclasses to the structure formation and stability of the lipid layers. As the native lipid matrix of the stratum corneum is a highly complex system, the recent investigations are carried out using simplified, but nevertheless realistic model membranes, applying biophysical and physicochemical techniques. The present chapter assesses the results of these investigations concerning the impact of the exceptionally long-chain ω-acyl ceramides (CER) such as CER[EOS] or CER[EOP]. Furthermore, as current studies have shown the importance of the short-chain ceramides such as CER[AP], these will also be discussed here. In addition, the recently introduced technique of neutron diffraction will be explained as seems to be the most promising method for the investigation of the nanostructure of stratum corneum lipid model membranes with its manifolds and specific advantages.