Depth profiling of Stratum corneum hydration in vivo: a comparison between conductance and confocal Raman spectroscopic measurements

Abstract

The high-frequency electrical conductance of tapestripped human skin in vivo can be used to evaluate the hydration profile of Stratum corneum (SC). Tape-stripping provides access to the underlying SC layers, and the conductance of these layers (as measured by the Skicon instrument) correlates well with their water content, as demonstrated by independent confocal Raman spectroscopic measurements. The correlation shows high interindividual variance and is not linear over the full measurement range of the instrument, but is helpful to discriminate between dry, normal and highly hydrated SC. The depth profile of hydration in tape-stripped SC corresponds to the one in intact SC only if the barrier function of the skin is not impaired. Thus, conductometry of tape-stripped skin must be used in conjunction with a method that allows to estimate the barrier damage inflicted to SC during the tape-stripping procedure, for example, measurement of the trans-epidermal water loss. The methodology described here is simple, rapid and minimally invasive, and it employs commercially available instrumentation that is cheap, portable and easy to use. This approach is applicable to in vivo estimation of the SC hydration in studies in the areas of dermatology, skin care and transdermal drug delivery.Key words: conductance -Skicon -skin barrier -tape-strippingtransepidermal water loss Please cite this paper as: Depth profiling of Stratum corneum hydration in vivo: a comparison between conductance and confocal Raman spectroscopic measurements.

Lipid composition and molecular interactions change with depth in the avian stratum corneum to regulate cutaneous water loss

“…6A; F likely to acclimatize to changes in temperature and humidity and thus maintain heat and water balance even in cold, dry conditions. In both winter-and summer-acclimatized house sparrows, the amount of water increased linearly with SC depth, a pattern that is consistent with studies done on humans (Warner et al, 1988;Boncheva et al, 2009). This increase in water content was positively correlated with the number of gauche defects present in the associated lipid lamellae.…”

“…Although most studies correlating barrier properties of the SC with lipid composition have assumed uniform water flux and lipid composition throughout the thickness of the SC, several studies on human SC have shown that water content increases in deeper layers of the SC (Warner et al, 1988;Bommannan et al, 1990;Boncheva et al, 2009). Furthermore, tape-stripping experiments on human SC show that overall lipid content decreases with depth in the uppermost 2 µm of the SC as corneocyte volume increases, and remains constant thereafter (Bommannan et al, 1990).…”

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

“…9,15,[26][27][28][29][30] Given that skin is able to take up water, it is reasonable to assume that water should also change its morphology and surface properties. In order to analyze these changes over time, we have employed 3D laser scanning microscopy, which allowed us to observe the surface of a skin replica under high magnification and provided 3D information.…”

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

“…Wu et al showed good validation of water content measurement between CRS and Karl Fischer method [21]. Boncheva et al also showed correlation between CRS and skin conductance related to water content measurement [22]. As optical coherence tomography (OCT) has been widely used for measurement of epidermal thickness [23][24][25][26][27], Crowthers et al published a validation study for SC thickness measurement between CRS and OCT [19].…”