No. 5 Vol. 42, No. 3, pp. 231‐236, 2008 Establishment of ex vivo stratum corneum lipid ordering analysis by electron spin resonance

Abstract

Electron spin resonance (ESR) spectra have been used for studying stratum corneum (SC) lipid ordering. Order parameter S obtained from ESR spectra is a good index for evaluating the fluidity of SC lipids in vitro. However, the method for evaluation of ex vivo SC lipids has not been established. A glass plate using a cyanoacrylate resin was used to strip the SC lipids. A single‐chain aliphatic spin probe, 5‐Doxylstearic acid (5‐DSA), was used. The SC samples were incubated in the 0.001% 5‐DSA in a 0.1% ethanolic aqueous solution for 60 min at 37°C. After the incubation, the excess spin probe was removed with distilled water, and then an ESR glass holder with the incubated SC sample was mounted in the ESR cavity. The newly designed ESR glass holder improved accuracy and reproducibility of sample preparations as well as ESR measurements. In conclusion, we have optimized the preparation method of ex vivo SC specimen and established accurate ex vivo ESR analyses of SC lipid ordering.Keywords: stratum corneum, lipid ordering, electron spin resonance, ESR, 5‐Doxylstearic acid, 5‐DSA, order parameter, SC, spin probe