Structure formation in binary mixtures of lipids and detergents: Self-assembly and vesicle division

TL;DR

This study uses coarse-grained molecular simulations to explore how lipid-detergent mixtures self-assemble into structures like bicelles and how detergents induce vesicle division or rupture, revealing mechanisms behind these processes.

Contribution

It provides new insights into the self-assembly and structural transformations of lipid-vesicle systems induced by detergents, including the formation of bicelles and vesicle division pathways.

Findings

Bicelles are stabilized by detergents around lipid bilayer disks.

Detergent adsorption induces spontaneous curvature leading to vesicle division or rupture.

Vesicle division mainly occurs via the inverse pathway of the modified stalk model.

Abstract

Self-assembly dynamics in binary surfactant mixtures and structure changes of lipid vesicles induced by detergent solution are studied using coarse-grained molecular simulations. Disk-shaped micelles, the bicelles, are stabilized by detergents surrounding the rim of a bilayer disk of lipids. The self-assembled bicelles are considerably smaller than bicelles formed from vesicle rupture, and their size is determined by the concentrations of lipids and detergents and the interactions between the two species. The detergent-adsorption induces spontaneous curvature of the vesicle bilayer and results in vesicle division into two vesicles or vesicle rupture into worm-like micelles. The division occurs mainly via the inverse pathway of the modified stalk model. For large spontaneous curvature of the monolayers of the detergents, a pore is often opened, thereby leading to vesicle division or worm-like micelle formation.