Characterization of the stratum corneum lipid matrix using fluorescence spectroscopy

Area of Science:

• Biophysics
• Materials Science
• Dermatology

Background:

• The stratum corneum (SC) acts as a crucial barrier in the skin.
• Understanding the dynamics of its lipid bilayer matrix is key to barrier function.
• Distearoyl-phosphatidylcholine (DSPC) serves as a model phospholipid bilayer for comparison.

Purpose of the Study:

• To investigate the dynamics and rigidity of the human stratum corneum (SC) lipid bilayer.
• To compare the SC lipid bilayer dynamics with that of a model distearoyl-phosphatidylcholine (DSPC) bilayer.
• To elucidate the factors contributing to the SC's barrier properties.

Main Methods:

• Utilized fluorescence techniques with 9-anthroyloxy fatty acid (AF) probes.
• AF probes partitioned into lipid bilayers to assess structure at different depths.
• Analyzed probe reorientation (emission, lifetime) and accessibility (iodide quenching).

Main Results:

• SC lipid bilayers exhibited more hindered fluorophore reorientation than DSPC bilayers, indicating greater rigidity.
• Iodide quenching revealed a gradient of accessibility within both bilayers, decreasing with depth.
• SC bilayers showed lower accessibility to iodide compared to DSPC bilayers.

Conclusions:

• SC lipid bilayers are significantly more rigid and less accessible than DSPC bilayers.
• Differences attributed to SC's anhydrous lipid composition (cholesterol, ceramides) versus DSPC's phospholipids.
• The rigid, anhydrous SC lipid environment forms an effective diffusion barrier for water and ions.