Confocal Raman spectroscopy: determination of natural moisturizing factor profile related to skin hydration

Abstract

Skin health and skin care to reduce the effects of aging are the main interests of many researchers. The skin is very important because it protects the body from various effects of the external environment, and studies of the largest organ of the human body have been conducted since antiquity. In skin, aging effects are severe enough to promote changes in cell structure and biochemical composition. In this study, we quantitatively analyzed the water content and natural moisturizing factor of human facial skin in vivo and in real time by confocal Raman spectroscopy. This non-invasive technique is capable of providing detailed information on the biochemical composition at different depth profiles in the skin. Methods: We studied 10 volunteers, phototype II (40 and 50 years old), using a confocal Raman system to examine the skin surface down to 25 μm. Raman spectra were obtained before product use (T0), and after 30 days of continuous use of cosmetics (T30). Results: The results show a significant increase of 6.4% in water content in the surface layer of the facial skin after the cosmetic use. The amounts of natural moisturizing factor (NMF) compounds were also increased. Urocanic acid underwent a greater change in relation to carboxylic acid pyrrolidone, with a 38.5% increase in the stratum corneum. Conclusion: Confocal Raman spectroscopy identified changes in the biochemical composition of the superficial layers of the epidermis, which suggests the anti-aging efficacy of the formulation.