Fluctuation mediated interactions due to rigidity mismatch and their effect on miscibility of lipid mixtures in multicomponent membranes

TL;DR

This paper investigates how membrane fluctuations, influenced by lipid rigidity differences, can alter the phase behavior of lipid mixtures in membranes, revealing that fluctuations can either promote or inhibit mixing depending on lipid properties.

Contribution

It introduces a mean-field theoretical approach to quantify how fluctuation-mediated interactions affect lipid mixture miscibility based on rigidity mismatches.

Findings

Fluctuations can either promote or inhibit lipid mixing.

Differences in Gaussian and bending rigidities determine fluctuation effects.

Membrane phase behavior is significantly influenced by fluctuation-mediated interactions.

Abstract

We consider how membrane fluctuations can modify the miscibility of lipid mixtures, that is to say how the phase diagram of a boundary-constrained membrane is modified when the membrane is allowed to fluctuate freely in the case of zero surface tension. In order for fluctuations to have an effect, the different lipid types must have differing Gaussian rigidities. We show, somewhat paradoxically, that fluctuation-induced interactions can be treated approximately in a mean-field type theory. Our calculations predict that, depending on the difference in bending and Gaussian rigidity of the lipids, membrane fluctuations can either favor or disfavor mixing.