The Physics of Stratum Corneum Lipid Membranes

TL;DR

This study uses atomistic molecular dynamics simulations to explore how lipid composition and structural variability in the skin's outer layer affect its barrier properties and physical characteristics.

Contribution

It provides detailed insights into the effects of lipid polydispersity on packing, hydrogen bonding, and mechanical properties of stratum corneum lipid membranes.

Findings

Understanding of tail packing in gel phase

Analysis of hydrogen bond networks among head groups

Estimation of bending moduli for SC lipid leaflets

Abstract

The Stratum Corneum (SC), the outermost layer of skin, comprises rigid corneocytes (keratin filled dead cells) in a specialized lipid matrix. The continuous lipid matrix provides the main barrier against uncontrolled water loss and invasion of external pathogens. Unlike all other biological lipid membranes (like intracellular organelles and plasma membranes), molecules in SC lipid matrix show small hydrophilic group and large variability in the length of the alkyl tails and in the numbers and positions of groups that are capable of forming hydrogen bonds. Molecular simulations provide a route for systematically probing the effects of each of these differences separately. In this article we present results from atomistic molecular dynamics of selected lipid bilayers and multilayers to probe the effect of these polydispersities. We address the nature of the tail packing in the gel-like phase, the hydrogen bond network among head groups, the bending moduli expected for leaflets comprising SC lipids, and the conformation of very long ceramide lipids (EOS) in multibilayer lipid assemblies.