Phase Diagrams of Multicomponent Lipid Vesicles: Effects of Spherical Topology and Finite Size

TL;DR

This paper investigates how the phase behavior of multicomponent lipid vesicles is influenced by spherical topology and finite size, revealing size-dependent effects and the impact of thermal fluctuations on phase stability.

Contribution

It introduces a modified Landau-Ginzburg model for spherical vesicles, analyzing size effects and thermal fluctuations on phase diagrams through analytical, numerical, and Monte Carlo methods.

Findings

Thermal fluctuations shift phase boundaries towards higher disorder.

Finite size effects are significant in small vesicles.

Phase diagrams depend on vesicle size, affecting experimental interpretations.

Abstract

We study the phase behavior of multicomponent lipid bilayer vesicles that can exhibit intriguing morphological patterns and lateral phase separation. We use a modified Landau-Ginzburg model capable of describing spatially uniform phases, microemulsions, and modulated phases on a spherical surface. We calculate its phase diagram for multiple vesicle sizes using analytical and numerical techniques as well as Monte Carlo simulations. Consistent with previous studies on planar systems, we find that thermal fluctuations move phase boundaries, stabilizing phases of higher disorder. We also show that the phase diagram is sensitive to the size of the system at small vesicle radii. Such finite size effects are likely relevant in experiments on small, unilamellar vesicles and should be considered in their comparison to theoretical and simulation results.