The Phase Behavior of Mixed Lipid Membranes in Presence of the Rippled Phase

TL;DR

This paper develops a model for mixed lipid membranes that explicitly includes the rippled phase, accurately predicting phase coexistence regions and matching experimental data for specific lipid mixtures.

Contribution

It extends a previous single-component membrane model to binary mixtures by incorporating composition-dependent parameters, capturing complex phase behaviors.

Findings

Phase diagrams show coexistence of liquid, solid, and rippled phases.

Model predictions align quantitatively with experimental data.

The approach elucidates the role of the rippled phase in membrane behavior.

Abstract

We propose a model describing liquid-solid phase coexistence in mixed lipid membranes by including explicitly the occurrence of a rippled phase. For a single component membrane, we employ a previous model in which the membrane thickness is used as an order parameter. As function of temperature, this model properly accounts for the phase behavior of the three possible membrane phases: solid, liquid and the rippled phase. Our primary aim is to explore extensions of this model to binary lipid mixtures by considering the composition dependence of important model parameters. The obtained phase diagrams show various liquid, solid and rippled phase coexistence regions, and are in quantitative agreement with the experimental ones for some specific lipid mixtures.