In Vivo Determination of Moisturizers Efficacy on Human Skin Hydration by Confocal Raman Spectroscopy

This research work deals with in vivo testing of the efficacy of commercial moisturizer products on the hydration of human skin, as there are various in vitro and ex vivo studies questioning their activity. Confocal Raman spectroscopy was used for this purpose of assessing the efficacy of moisturizers on skin hydration mainly owing to its simple, non-invasive, non-destructive, timesaving, and cost-effective nature. Water content and natural moisturizing factor (NMF) of stratum corneum were analyzed and compared using this method at high wavenumber (2500-4000cm(-1)) and fingerprint (400-1800cm(-1)) spectral regions, respectively, as these two parameters are correlated to skin hydration. Four commercial moisturizer products of different brands were tested on volar forearm region of healthy human female volunteers. This study was conducted for a period of 30days with 0, 7, and 30days as time points of analysis. The results of this study clearly indicate that not all the moisturizer products hydrate the skin to the expected levels, and this extent of skin hydration varies with duration of application of these products.