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Updated: Aug 3, 2025

Resolving Water, Proteins, and Lipids from In Vivo Confocal Raman Spectra of Stratum Corneum through a Chemometric Approach
Published on: September 26, 2019
Effects of solar radiations on stratum corneum hydration: Part I, protective role of skin surface lipids
Ali Assi1, Rime Michael-Jubeli1, Hélène Duplan2
1Lip(Sys)2, Chimie Analytique Pharmaceutique (EA4041 Groupe de Chimie Analytique de Paris-Saclay), Université Paris-Sud, Université Paris-Saclay, Orsay, France.
Abstract:
This study used Raman spectroscopy to develop a new approach to evaluate the effects of solar radiation on the stratum corneum (SC). The method measures the SC's hydration and dehydration kinetics by calculating the vOH/vCH ratio to monitor the relative water content during the drying process. The study also investigated the role of skin surface lipids (SSLs) in protecting the SC from solar radiation. The SSLs film is a complex mixture of free fatty acids, triglycerides, wax esters, squalene, free and esterified cholesterols, that play a crucial role in the skin's barrier function. The results showed that solar radiation alters the water content and balance within the SC, and SSLs provide protection by acting as an optical filter by absorbing some of the energy of the solar light. This is confirmed by high temperature gas chromatography coupled to mass spectrometry analyses by revealing a decrease in specific lipids after irradiating the SSLs .
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