Polymer-induced tubulation in lipid vesicles

TL;DR

This paper presents a theoretical and numerical study of how amphiphilic polymers induce tubulation in lipid vesicles, explaining the mechanism and matching recent experimental observations.

Contribution

It introduces a combined analytical and phase-field modeling approach to explain polymer-induced tubulation in lipid vesicles, aligning with experimental findings.

Findings

Energy profile shows stable tube formation at certain parameters

Numerical simulations confirm tube growth with polymer addition

Vesicle shapes revert to buds after polymer removal

Abstract

A mechanism of extraction of tubular membranes from a lipid vesicle is presented. A concentration gradient of anchoring amphiphilic polymers generates tubes from bud-like vesicle protrusions. We explain this mechanism in the framework of the Canham-Helfrich model. The energy profile is analytically calculated and a tube with a fixed length, corresponding to an energy minimum, is obtained in a certain regime of parameters. Further, using a phase-field model, we corroborate these results numerically. We obtain the growth of tubes when a polymer source is added, and the bud-like shape after removal of the polymer source, in accordance with recent experimental results.