Phase Separation on Bicontinuous Cubic Membranes: Symmetry Breaking, Re-entrant and Domain Facetting

TL;DR

This paper investigates how binary lipid mixtures in bicontinuous cubic phases undergo complex phase separation behaviors influenced by membrane curvature and line tension, revealing symmetry breaking, reentrant phenomena, and domain facetting.

Contribution

It introduces a comprehensive analysis of phase separation in bicontinuous cubic membranes, highlighting the roles of curvature, line tension, and topology in shaping membrane morphologies.

Findings

Symmetry breaking of membrane morphologies observed.

Reentrant phase behavior due to domain bridging.

Facetting of lipid domains explained by surface symmetry.

Abstract

We study the phase separation of binary lipid mixtures that form bicontinuous cubic phases. The competition between non-uniform Gaussian membrane curvature and line tension leads to a very rich phase diagram, where we observe symmetry breaking of the membrane morphologies and reentrant phenomena due to the formation of bridges between segregated domains. Upon increasing the line tension contribution, we also find facetting of lipid domains that we explain using a simple argument based on the symmetry of the underlying surface and topology.