Basic nanostructure of stratum corneum lipid matrices based on ceramides [EOS] and [AP]: a neutron diffraction study.

Area of Science:

• Biophysics
• Materials Science
• Dermatology

Background:

• Stratum Corneum (SC) lipids are vital for skin barrier function.
• Omega-acylceramides like [EOS] and free fatty acids (FFAs) are key components.
• Previous models suggest [EOS] and FFAs are necessary for SC lipid lamellar phases and barrier integrity.

Purpose of the Study:

• To investigate the nanostructure of SC lipid model membranes using neutron diffraction.
• To determine the influence of the free fatty acid behenic acid (BA) on membrane structure.
• To elucidate the localization of BA within SC lipid model membranes containing ceramides [EOS] and [AP].

Main Methods:

• Neutron diffraction was employed to analyze SC lipid model membranes.
• Fourier synthesis was used to derive internal nanostructure from diffraction patterns.
• Deuterated BA and hydration experiments were utilized to pinpoint FFA location and assess membrane hydration.

Main Results:

• The exceptionally long ceramide [EOS] was found to arrange in a short-periodicity phase formed by ceramide [AP].
• Ceramide [EOS] spans the entire bilayer and extends into adjacent bilayers.
• Deuterated BA confirmed its precise localization within the SC lipid model membrane.
• The SC mimic system exhibited minimal intermembrane hydration (~1 Å).

Conclusions:

• The study elucidates the structural organization of key SC lipids, including ceramide [EOS] and ceramide [AP].
• The precise localization of free fatty acid BA within the SC lipid model membrane was determined.
• Minimal intermembrane hydration suggests close proximity of headgroups in neighboring leaflets, impacting barrier properties.