DOI: 10.1007/s101890070039
A molecular model for the line tension of lipid membranes
S. MayInstitut für Biochemie und Biophysik, Friedrich-Schiller-Universität Jena, Philosophenweg 12, Jena 07743, Germany
(Received 2 January 2000)
Abstract
The line tension of a symmetric, lipid bilayer in its liquid-crystalline state
is calculated on the basis of a molecular lipid model.
The lipid model extends the opposing forces model by an expression for
the conformational free energy of the hydrocarbon chains. We consider a
membrane edge that consists of a perturbed bilayer covered by a section of a
cylinder-like micelle. The structural rearrangement of the lipids implies an
excess free energy which we minimize with respect to the cross-sectional shape
of the membrane edge, including both the micellar and the bilayer region.
The line tension is derived as a function of molecular lipid properties, like
the lipid chain length or the head group interaction strength. We also relate
it to the spontaneous curvature of the lipid layer.
We find the line tension to become smaller for lipid layers
that tend to curve more towards the hydrophobic core. Our predictions for
the line tension and their relation to experimentally derived values are
discussed.
87.16.-b - Subcellular structure and processes.
68.10.-m - Fluid surfaces and fluid-fluid interfaces.
68.10.Et - Interface elasticity, viscosity, and viscoelasticity.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2000
