Structural Analysis of the Stratum Corneum using EPR and EPR Imaging with Stable Spin Probes

X-band (9.4 GHz) electron paramagnetic resonance (EPR) and electron paramagnetic resonance imaging (EPRI) were used for elucidating structural aspects of the stratum corneum (SC). We found that psoriasis vulgaris (PV)-SC has a less-ordered structure than that of the control SC, indicating the abnormal architecture of PV-SC. Different spectra were observed for the PV-SC. The three-line spectral pattern suggests that the 5-doxylstearic acid (5-DSA) is mobile or less rigid in the SC. The simulated order parameter (S₀) value obtained for 5-DSA in the SC was approximately 0.20. The statistical analysis suggests that the value of the PV-SC is significantly smaller than that of the control (p < 0.01). Thus, we suggest that this EPR assay is of great use for evaluating SC function. In addition, the EPRI of various SC samples provides a useful image concerning SC status. A strong red image was observed for the PV skin. No red lesion region was observed in the control. The EPR images differentiated various sizes and number distribution concerning the disordered states in the SC.