Confined Multilamellae Prefer Cylindrical Morphology

TL;DR

This paper explains the formation of myelin structures in lipid dispersions as a balance between bilayer repulsion and curvature energy, providing a geometric model and numerical estimates for stability conditions.

Contribution

It introduces a geometric argument to explain myelin morphology formation and predicts dehydration levels needed for stability, advancing understanding of nonequilibrium lipid structures.

Findings

Myelin structures are stabilized by increased bilayer spacing reducing repulsion.

A geometric model predicts dehydration thresholds for myelin formation.

Numerical estimates match experimental observations.

Abstract

By evaporating a drop of lipid dispersion we generate the myelin morphology often seen in dissolving surfactant powders. We explain these puzzling nonequilibrium structures using a geometric argument: The bilayer repeat spacing increases and thus the repulsion between bilayers decreases when a multilamellar disk is converted into a myelin without gain or loss of material and with number of bilayers unchanged. Sufficient reduction in bilayer repulsion can compensate for the cost in curvature energy, leading to a net stability of the myelin structure. A numerical estimate predicts the degree of dehydration required to favor myelin structures over flat lamellae.