Shape fluctuations and elastic properties of two-component bilayer membranes

TL;DR

This study investigates how the elastic properties and shape fluctuations of two-component bilayer membranes depend nonmonotonically on the composition, revealing complex behavior not explained by simple rules.

Contribution

It provides a detailed analysis of the elastic properties of two-component bilayers with different amphiphile lengths using molecular dynamics simulations.

Findings

Bending rigidity varies nonmonotonically with composition.

Intrinsic area shows a maximum near equal mixture.

Shape fluctuations are influenced by amphiphile length differences.

Abstract

The elastic properties of two-component bilayer membranes are studied using a coarse grain model for amphiphilic molecules. The two species of amphiphiles considered here differ only in their length. Molecular Dynamics simulations are performed in order to analyze the shape fluctuations of the two-component bilayer membranes and to determine their bending rigidity. Both the bending rigidity and its inverse are found to be nonmonotonic functions of the mole fraction $x_{\rm B}$ of the shorter B-amphiphiles and, thus, do not satisfy a simple lever rule. The intrinsic area of the bilayer also exhibits a nonmonotonic dependence on $x_{\rm B}$ and a maximum close to $x_{\rm B} \simeq 1/2$.