Attractive forces between anisotropic inclusions in the membrane of a vesicle

TL;DR

This study uses Monte Carlo simulations to analyze the entropic, fluctuation-induced interactions between rod-like inclusions in vesicle membranes, revealing attractive, short-range potentials influenced by membrane bending properties.

Contribution

It introduces a simulation approach to quantify the effective interactions between anisotropic inclusions in vesicle membranes, accounting for lattice artifacts and finite-size effects.

Findings

Effective potential is attractive and short-range.

Potential well depth is about one-tenth of the bending modulus.

Interactions depend on mutual distance and orientation.

Abstract

The fluctuation-induced interaction between two rod-like, rigid inclusions in a fluid vesicle is studied by means of canonical ensemble Monte Carlo simulations. The vesicle membrane is represented by a triangulated network of hard spheres. Five rigidly connected hard spheres form rod-like inclusions that can leap between sites of the triangular network. Their effective interaction potential is computed as a function of mutual distance and angle of the inclusions. On account of the hard-core potential among these, the nature of the potential is purely entropic. Special precaution is taken to reduce lattice artifacts and the influence of finite-size effects due to the spherical geometry. Our results show that the effective potential is attractive and short-range compared with the rod length L. Its well depth is of the order of \kappa/10, where \kappa is the bending modulus.