Thermal dependence of Raman descriptors of ceramides. Part I: effect of double bonds in hydrocarbon chains

Abstract

The barrier function of the stratum corneum (SC) is directly related to: (1) the nature and the composition of the lipids in the intercellular spaces and (2) the conformational order of the ceramides within this layer. The aim of this work was to determine Raman descriptors for the lateral packing, the conformation, and the structure of ceramides III, IIIA, and IIIB issued from the same phytosphingosine ceramide and only presenting differences in the number of double bonds in the hydrocarbon chains. Temperature was used as a variable parameter in order to access the different states of the conformational order and supramolecular organization of the three ceramides, and Raman spectra were collected at each temperature. By using a high-resolution Raman spectrometer and working on a spectral range going from 400 to 3,200 cm(-1), we were able to assess simultaneously the different descriptors of structure and organization, i.e., the methyl rocking bands (840-910 cm(-1)) for the chain-end conformers, the C-C skeletal stretching (1,060-1,130 cm(-1)), and the CH stretching region (2,800-3,050 cm(-1)) for the trans and gauche conformations, the CH(2) scissoring bands to follow the changes in the lateral packing, and finally the amide I band to evaluate the state of the H-bonds between the polar and head groups.

In vivo Raman Microspectroscopy: Intra- and Intersubject Variability of Stratum Corneum Spectral Markers

“…material). Generally, our Raman assignments correlate with those in the literature [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46]. The Raman spectrum of the SC is dominated by vibrational bands of its structural proteins, lipids, and tissue water.…”

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).…”

Raman spectroscopic analysis of human skin tissue sectionsex-vivo: evaluation of the effects of tissue processing and dewaxing

“…Fitted peak intensities are reproducible within 10% and are normalised to the band at ~2932 cm 1 . The peaks in the high number region predominantly originate from CH, CH 2 and CH 3 stretching, and from literature, many can be assigned to lipids, the remainder being assigned to proteins 34,35,82,83 .…”

“…In dermatological research, FTIR has been employed for tumour detection in colon and skin biopsies 5,29,30 . Raman spectroscopy has been demonstrated to provide an accurate diagnosis to distinguish basal cell carcinoma from surrounding normal tissue 3133 and can also been used as an efficient tool for examination of skin biochemical structure and content 34,35 of interest for dermal application of cosmetic and pharmacological agents.…”