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

Abstract

Introduction: 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.

Effect of an Emollient Emulsion Containing 15.0% of Caprylic/Capric Triglyceride on the Urocanic Acid of the Stratum Corneum

“…The concentrations of both isomers of UCA almost doubled in the SC treated with the emollient emulsion. Our results indicated that the application of the emollient sample, for 2 h, increased the UCA concentration in the outermost layers of the SC; these results agreed with the ones from Teixeira et al ( 2014), when the UCA was analyzed as a biomarker for the NMF under 30 days of cosmetic product use, and had an increase of 38.5% [25]. Total UCA concentration (the sum of the trans-and cis-UCA) from the SC samples generated a significant increase when the emollient emulsion was applied to the subjects' forearms in comparison to the non-treated SC (Wilcoxin matched-pairs signed rank test, two tailed, n = 12, α = 0.05) (Figure 2).…”

“…The concentrations of both isomers of UCA almost doubled in the SC treated with the emollient emulsion. Our results indicated that the application of the emollient sample, for 2 h, increased the UCA concentration in the outermost layers of the SC; these results agreed with the ones from Teixeira et al ( 2014), when the UCA was analyzed as a biomarker for the NMF under 30 days of cosmetic product use, and had an increase of 38.5% [25]. The influence of artificial UV irradiation was also evaluated over the SC obtained by the tape stripping method.…”

Confocal Raman spectroscopy is suitable to assess hair cleansing‐derived skin dryness on human scalp

“…CRS was also used in vivo to observe the effects of antiage cosmetic products on the level of hydration and NMF. 15 The effects of the investigated products increased the level of hydration and enhanced NMF.…”

In vivo confocal Raman spectroscopy and molecular dynamics analysis of penetration of retinyl acetate into stratum corneum

“…In vivo confocal Raman spectroscopy is a powerful non-invasive technique that allows an analysis of skin constituents [24][25][26][27][28][29] related to biochemical composition, permeation processes [27][28][29][30] of the skin and RA, and it can replace other methods such as skin biopsy and tape tripping [31,32].…”