Raman spectroscopy: a tool for biomechanical characterization of Stratum Corneum

Abstract

The mechanical properties of the Stratum Corneum (SC) have been studied by different authors at the macroscopic level, but the modification of its ultra structure during mechanical extension remains unknown. Moreover, little is described about the effect of the mechanical stress on SC barrier function. In this study, we have examined the SC structure changes, at the molecular level, during uniaxial tensile experiments. This was performed on isolated SC samples using Raman spectroscopy. We could identify the strain status of the analyzed samples by using combination of Raman spectra and Partial Least Squares processing. In addition, this approach provided information about lipids and proteins behavior during the sample extension. The structure of the intercellular lipids bilayer became less organized up to ~9% deformation. For higher strains, a plateau corresponding to the minimum organization is observed till the complete failure of the sample. In the same time, protein structures including desmosomes, were characterized by monotonic secondary structure modifications for deformations up to ~9% followed by a plateau. These observations are relevantly demonstrating the effect of extension on the skin barrier state. Such an approach could be objectively used for clinical applications to evaluate skin discomfort degree and skin elastic behavior. This could therefore help with proof of efficacy for cosmetic and dermatologic products. Copyright © 2013 John Wiley & Sons, Ltd.

The influence of surface charge and photo-reactivity on skin-permeation enhancer property of nano-TiO2 in ex vivo pig skin model under indoor light

“…This could be consistent with a partial structural rearranging of the lipidic chains (Tfayli et al, 2012). In fact, in lipids, the ratio of the symmetric methylene C-H stretching-mode intensities (peak height I2890/I2850) is sensitive to the packing order of the acyl chains and the observed relative increase of intensity of the 2850 cm -1 band with respect to 2890 cm -1 may account for a change of the lipids bilayer structure (Vyumvuhore et al, 2013). This phenomenon, occurring with naked AR, but not with coated TiO2 with similar titania core, is possibly due to physical interaction of nano-TiO2 with the SC lipids and/or to some TiO2-induced chemical oxidative damage (Gaber and Peticolas, 1977;Gniadecka et al, 1998 andWegener et al, 1996).…”

Comparison of structure and organization of cutaneous lipids in a reconstructed skin model and human skin: spectroscopic imaging and chromatographic profiling

“…The main differences are observed in the composition of ceramides. The use of Raman spectroscopy to examine the lateral packing and conformational order in SC lipids is well established (22,(26)(27)(28)(29)(30). The secondary structure and folding of keratin has similarly been assessed using Raman spectroscopy (22).…”

“…Comparison of the morphology at macroscopic and microscopic levels, analyses of biochemical markers, phototoxicity and irritancy testing have been performed (2,7,(10)(11)(12)(13)(14). These constructs have, however, been demonstrated to be limited as models for human skin barrier function (1,(15)(16)(17)(18)(19)(20)(21), determined by composition and structure of lipids in the stratum corneum (SC) (22)(23)(24)(25). However, no systematic studies of the structure and organization of cutaneous lipids in RSMs compared with human skin have been presented.…”

Analysis of Human and Porcine Skin in vivo/ex vivo for Penetration of Selected Oils by Confocal Raman Microscopy

“…External stressors are able to influence the physiology of the human skin's stratum corneum. Among them are mechanical influence [5], solar irradiation [6,7,8], environmental pollutants [9,10], and topically applied formulations [11,12]. Oils have been topically used as the basis of many skin care products and ointments for a long time in the cosmetic industry and medicine [13,14,15,16].…”