A depth-dependent profile of the lipid conformation and lateral packing order of the stratum corneum in vivo measured using Raman microscopy

Abstract

The intercellular lipid structure of the stratum corneum (SC) plays a key role in skin barrier function. A depth profile of the intercellular lipid conformation and the lipid lateral packing order were measured in vivo in the human SC using confocal Raman microscopy. The depth profiles of the 2880 cm(-1)/2850 cm(-1) peak ratio intensity, which represent the C-H stretching and lateral packing order of lipids, and the 1080 cm(-1)/(1130 cm(-1) + 1060 cm(-1)) peak ratio, which represents the C-C skeleton vibration and trans-gauche conformation order of lipids, were investigated. The influence of keratin on the lipid peaks at 2850 cm(-1) and 2880 cm(-1) was excluded by the developed mathematical algorithm. The results show that the trans-conformation and lateral packing order of the intercellular lipids reach their maximum value in the SC at 20-40% of its depth and then decrease towards the stratum granulosum. These results show that at a depth of 20-40% (normally corresponding to a depth of 4-8 μm) the SC exhibits the most ordered lipids and therefore the highest skin barrier function. The lateral packing of lipids is more disordered on the surface and in the deeper parts of the SC, which may be associated with a reduced skin barrier function.

Radical-Scavenging Activity of a Sunscreen Enriched by Antioxidants Providing Protection in the Whole Solar Spectral Range

“…4), the maximum sunscreen concentration was detectable near the skin surface, at a depth of 11.2 ± 3.0 µm after 6 h of penetration, respectively. The obtained results are in strong agreement with the lipid-ordering profile of the stratum corneum, which provides the maximum skin barrier function at depths around 10 µm [40]. Thus, the majority of the formulation ingredients remains on the skin surface and in the superficial layers, and does not penetrate into the viable layers of the epidermis.…”

Lipid organization and stratum corneum thickness determined in vivo in human skin analyzing lipid–keratin peak (2820–3030 cm−1) using confocal Raman microscopy

“…a, the maximum position of the Gaussian function centered at 2850 cm −1 exhibits higher values in the superficial 10% of the SC and near the boundary between SC and SG. This means that at these depths, the lipid states are more disordered compared to the state of the lipids in the medium SC layers, which was confirmed by previously published data …”

“…This is plausible as the lipid concentration decreases towards the deeper layers of the SC and the gauche conformation (disordered packing) of the lipids' carbon backbone gets more prominent . The steep slope of the sharpness in the range 10–20 µm skin depth might be because of the synergetic effect of the decrease of lipid concentration and the increase of disordered lipids' state.…”

Hydrogen bound water profiles in the skin influenced by optical clearing molecular agents—Quantitative analysis using confocal Raman microscopy

“…The low variability components of the Raman spectra in the HWN range were classified as noise and were therefore filtered using principal component analysis . In order to do so, the first four principal components were used to reconstruct the Raman spectra.…”