Structure of rat skin after application of electret characterized by DSC

Polypropylene (PP) electrets with surface potential of −500V, −1000V and −2000V were prepared by constant voltage corona charging. The electrets were applied to excised rat skin for 2 hours respectively and then the skin samples were analyzed with the differential scanning calorimetry (DSC) technique to study the alteration of lipid organization of the skin. There were three peaks at 63°C, 82.7°C and 115.1°C in the DSC spectra for rat skin untreated, which have been assigned essentially to lipid, lipid-protein and protein alterations. For −500V electret treated-skin sample, only a single peak appeared at 79.1°C. With the increase of electret surface potential from −500V to −2000V, the transition temperature and peak areas at moderate decreased first and then increased. The negative electret could result in the transition of stratum corneum (SC) lipid from gel to liquid crystal and protein transition from α helix structure to β folding structure. The regulation action of electret to skin mircostructure presented an effect of "potential window".