Assessment of human stratum corneum thickness and its barrier properties by in‐vivo confocal Raman spectroscopy

Abstract

IFSCC Magazine, 12 (2009) (1) 9–15 Measurement of water concentration profiles across living human skin by confocal Raman spectroscopy has developed into a powerful tool for a better understanding of distribution and function of water in the epidermis. From the water profile across the epidermis the border between stratum corneum and stratum granulosum can be estimated. This is due to the steep drop in water concentration from the inner to the outer side of the stratum corneum. Water content drops from approximately 70% at the inner stratum corneum to only 30% at the skin surface. This slope of the curve becomes clearly flatter in the stratum granulosum. A second parameter is usually taken from confocal Raman spectroscopy to define the stratum corneum border. This is the content of natural moisturization factor (NMF), which should be present only in the stratum corneum. Located at the depth at which the NMF content levels off and the slope of the water profile curve changes is the stratum corneum border. The goal of this work was to develop stratum corneum thickness detection into a robust and semi‐automated measurement relying only on the water profile. Further, the aim was to base the empirical findings of water distribution in the epidermis on a well established theory, Fick's law of diffusion. A mathematical model was developed to fit the water profile curve for a robust and automated detection of the stratum corneum border. In addition, the new model automatically resulted in an accurately determined slope of the water concentration curve in the stratum corneum. This slope, or more exactly the gradient, is one of two parameters directly related to transepidermal water transport across the stratum corneum. Keywords: Barrier function, Fick's law, Raman spectroscopy, stratum corneum, transepidermal water loss

In vivo confirmation of hydration-induced changes in human-skin thickness, roughness and interaction with the environment

“…This behavior can be explained by the barrier function of the SC, as the threshold depth corresponds to the location of the lower SC, known to act as a barrier layer for water. [46][47][48][49] Another threshold can be observed, suggesting that the skin was more accessible to penetration of water, and that it occurred faster at depths for the first few micrometers of the SC. The time dependent change of the hydration level of the SSC (Fig.…”

A new topical panthenol-containing emollient: skin-moisturizing effect following single and prolonged usage in healthy adults, and tolerability in healthy infants

“…Raman spectroscopy, an established noninvasive method (18,19), was used to evaluate the change in water distribution within the SC after a single application of NTP-CE. Approximately 10 water profile measurements were performed in the center of each test area per assessment time as described before (20,21), thereby investigating the skin down to a depth of about 30 lm. The SC was divided into three equally spaced compartments (22), and the change in water content within each SC compartment was calculated according to the area under the curve (AUC) (20).…”

“…Approximately 10 water profile measurements were performed in the center of each test area per assessment time as described before (20,21), thereby investigating the skin down to a depth of about 30 lm. The SC was divided into three equally spaced compartments (22), and the change in water content within each SC compartment was calculated according to the area under the curve (AUC) (20). In addition, the water gradient (slope of water increase) from outer to inner SC and SC thickness were calculated (20,21).…”

“…The SC was divided into three equally spaced compartments (22), and the change in water content within each SC compartment was calculated according to the area under the curve (AUC) (20). In addition, the water gradient (slope of water increase) from outer to inner SC and SC thickness were calculated (20,21).…”

A Consensus Modeling Approach for the Determination of Stratum Corneum Thickness Using In-Vivo Confocal Raman Spectroscopy

“…A single technique that can measure both water content and SC thickness would be of great value as a clinical measurement device. In-vivo confocal Raman spectroscopy (CRS) has evolved as a single clinical measurement device capable of making both measurements based on the spectra of skin with depth into the SC before and after treatments [11,[16][17][18][19][20]. Although capable of providing SC thickness values, a consistent, reliable, SC thickness measurement from CRS has not emerged and of those methods that have been proposed, there is no agreement on best practices and no direct correlation with an established SC measurement method.…”