The Binding and Aggregation of Anisotropic Nanoparticles on Cylindrical Lipid Membranes

Abstract

Golgi and endoplasmic reticulum in eukaryotic cells owe their complex membrane conformations to specialized curvature inducing proteins. Using coarse-grained molecular dynamics simulations, we investigated the aggregation and binding of anisotropically curved nanoparticles to cylindrical lipid membranes that are reminiscent of the BAR-domain containing proteins. Here we consider only the case where the nanoparticle–nanoparticle interaction is repulsive and only the concave surface of the nanoparticle interacts attractively with the lipid head groups. We found that the ability of a nanoparticle to bind to a cylindrical membrane depends on the nanoparticle-lipid interaction strength, mismatch in nanoparticle-membrane curvature, and the nanoparticles's arclength. In particular, we found that the minimum interaction strength required for a single nanoparticle binding increases with mismatch in nanoparticle-membrane curvature or increasing the nanoparticle arclength. Additionally, nanoparticles were found to accommodate a tilt angle on cylindrical membranes having a radius of curvature less that of the bound nanoparticles. This tilt angle is well maintained for nanoparticles with large arclength, while shorter nanoparticles are able to rotationally diffuse more freely. These results are consistent for larger numbers of nanoparticles where they aggregate into various structures depending on nanoparticle-lipid interaction strength, mismatch in nanoparticle-membrane curvature, and the nanoparticle's arclength. This aggregation by many nanoparticle is reminiscent of protein aggregates formed by the BAR-protein family, in spite of the simplicity of our nanoparticles.