Noninvasive in Vivo Measurement of Natural Moisturizing Factor Content in Stratum Corneum of Human Skin by Attenuated Total Reflection Infrared Spectroscopy

Abstract

Water-soluble components in the outermost layer of human skin are called natural moisturizing factor (NMF). NMF is one of the most important factors of skin moisturizing mechanisms. It is known that individuals with psoriasis, atopic dermatitis, and ichthyosis possess skin with lower-than-normal NMF content. Therefore, a noninvasive method for NMF content measurement of the human skin would be very useful to both dermatologists and cosmetic chemists. We attempted to measure the NMF content by focusing on the infrared wavelengths that are commonly absorbed by most NMF components. In order to estimate the intensity of absorption that is common to NMF components, we simulated the attenuated total reflection (ATR)-infrared (IR) spectrum of human skin by the combination of multiple Gaussian peaks. The spectroscopic signal of NMF linearly correlated with the actual NMF content measured by chromatographic methods. Therefore, we concluded that we can determine the skin surface NMF content from the ATR-IR spectrum of skin. This noninvasive and simple method is useful for studying NMF in a wide variety of skin regions and under various skin conditions.