This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.094292v1 92/8/2785    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gooris, G. S. Articles by Bouwstra, J. A. Search for Related Content PubMed PubMed Citation Articles by Gooris, G. S. Articles by Bouwstra, J. A.

Infrared Spectroscopic Study of Stratum Corneum Model Membranes Prepared from Human Ceramides, Cholesterol, and Fatty Acids

Leiden/Amsterdam Center for Drug Research, Department of Drug Delivery Technology, Leiden University, 2300 RA Leiden, The Netherlands

Correspondence: Address reprint requests to Prof. J. A. Bouwstra, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden University, PO Box 9502 2300 RA Leiden, The Netherlands. Tel.: 31(0)71-527-42-08; Fax: 31(0)71-527-45-65; E-mail: bouwstra{at}chem.leidenuniv.nl.

The outermost layer of the skin, the stratum corneum, consists of corneocytes surrounded by lipid domains. The main lipid classes in stratum corneum are cholesterol, ceramides (CER), and free fatty acids forming two crystalline lamellar phases. However, only limited information is available on whether the various lipid classes participate in the same crystalline lattices or if separate domains are formed within the lipid lamellae. In this article infrared spectroscopic studies are reported of hydrated mixtures prepared from cholesterol, human CER, and free fatty acids. Evaluation of the methylene stretching vibrations revealed a conformational disordering starting at 60°C for all mixtures. Examination of the rotational ordering (scissoring and rocking vibrations) of mixtures prepared from equimolar cholesterol and CER with a variation in the level of free fatty acids showed that at lower free fatty acid content orthorhombic and hexagonal domains coexist in the lipid lamellae. Increasing the fatty acid level to an equimolar cholesterol/CER/fatty acid mixture reveals the dominant presence of an orthorhombic lattice, confirming x-ray diffraction studies. Replacing the protonated free fatty acid chains by their perdeuterated counterparts demonstrates that free fatty acids and CER participate in the same orthorhombic lattice up to a level of slightly less than 1:1:0.75 cholesterol/CER/free fatty acids molar ratio but that free fatty acids also form separate domains within the lipid lamellae at equimolar ratios at room temperature. However, no evidence for this has been observed at 32°C. Extrapolating these findings to the situation in stratum corneum led us conclude that in stratum corneum, fatty acids and CER participate in the orthorhombic lattice at 32°C, the skin temperature.

This article has been cited by other articles:

				I. Plasencia, L. Norlen, and L. A. Bagatolli Direct Visualization of Lipid Domains in Human Skin Stratum Corneum's Lipid Membranes: Effect of pH and Temperature Biophys. J., November 1, 2007; 93(9): 3142 - 3155. [Abstract] [Full Text] [PDF]