THERMOANALYTICAL PROBES FOR ANALYSIS OF PHYSICAL-PROPERTIES OF STRATUM-CORNEUM

[摘要] Thermomechanical analysis (TMA) measurements were used to characterize physical properties of normal and treated stratum corneum. TMA measured changes in overall mechanical and dimensional properties of the material as a result of temperature-induced transformations such as lipid melting, protein conformational changes and glass transitions. TMA indicated several softening transitions in normal human stratum corneum which occurred at about 50, 150 and 260.degree. C. Differential scanning calorimetry and thermomechanical analysis studies showed that the 50.degree. C softening was related to lipid melting and protein side chain motion, while the other observed transitions appeared to result from a change in state of the protein organization and decomposition, respectively. These particular parameters were sensitive to changes in composition and macromolecular structure of the stratum corneum brought about by disease and chemical alteration. Shifts in temperature of the 2nd softening transition are observed between normal stratum corneum and stratum corneum treated with a retinoic acid product, occlusive therapy, petrolatum, propylene glycol-ethanol and normal saline. These shifts implied a possible alteration of the higher-level organization of the keratin in the stratum corneum.