Examination of the effect of Stratum Corneum isolation process on the integrity of the barrier function: a confocal Raman spectroscopy study

Stratum Corneum (SC) is the most superficial layer of the epidermis. It plays the main barrier role against water loss and the aggression of external chemical and biological substances. Thermal treatment in warm purified water followed by trypsin incubation of excised human skin is a well-established in vitro method for SC removal. Different protocols can be found in literature, but little is described about the effect of temperature and trypsin during isolation process on its barrier function.In this study, we have examined the epidermis and SC matrix structural change upon isolation by means of confocal Raman spectroscopy.Several spectral features, i.e. in-depth and planar lateral packing, conformational order and secondary structure have been investigated to reveal modifications in the structural properties of the lipids and proteins in the SC. Thermal treatment at 60°C leads to a losing in compactness and a steeper concentration of the lipid and protein descriptors while the trypsinization step modifies the organization of the proteins and of the lipid barrier, leading to a domain organization.The present study improves the knowledge of the effects on the barrier function of SC removal protocol.