Deformation of Equilibrium Shape of a Vesicle Induced by Injected Flexible Polymers

TL;DR

This paper models how enclosed flexible polymers can deform vesicle shapes, combining phase field and self-consistent field theories to analyze stability and shape transitions relevant to drug delivery and endocytosis.

Contribution

It introduces a coupled theoretical model using phase field and self-consistent field theories to study vesicle deformation caused by enclosed polymers, which is novel.

Findings

Polymer chain length affects vesicle shape stability.

Introduction of polymers induces vesicle shape deformation.

Prolate shapes are relatively more stable than oblate shapes under certain conditions.

Abstract

Using field theoretic approach, we study equilibrium shape deformation of a vesicle induced by the presence of enclosed flexible polymers, which is a simple model of drug delivery system or endocytosis. To evaluate the total free energy of this system, it is necessary to calculate the bending elastic energy of the membrane, the conformation entropy of the polymers and their interactions. For this purpose, we combine phase field theory for the membrane and self-consistent field theory for the polymers. Simulations on this coupled model system for axiosymmetric shapes show a shape deformation of the vesicle induced by introducing polymers into it. We examined the dependence of the stability of the vesicle shape on the chain length of the polymers and the packing ratio of the vesicle. We present a simple model calculation that shows the relative stability of the prolate shape compared to the oblate shape.