Interaction of chiral rafts in self-assembled colloidal membranes

TL;DR

This study models the interactions of chiral rafts in colloidal membranes using elasticity theory, predicting their tilt profiles and interaction forces, and finds good agreement with experimental observations.

Contribution

It introduces a theoretical framework to predict raft interactions in colloidal membranes, extending understanding beyond previous experimental work.

Findings

Interaction range set by chiral penetration depth

Good agreement with experimental interaction strength and range

No complete collapse of data when rescaled by edge tilt angle

Abstract

Colloidal membranes are monolayer assemblies of rodlike particles that capture the long-wavelength properties of lipid bilayer membranes on the colloidal scale. Recent experiments on colloidal membranes formed by chiral rodlike viruses showed that introducing a second species of virus with different length and opposite chirality leads to the formation of rafts --- micron-sized domains of one virus species floating in a background of the other viruses [Sharma et al., Nature 513, 77 (2014)]. In this article we study the interaction of such rafts using liquid crystal elasticity theory. By numerically minimizing the director elastic free energy, we predict the tilt angle profile for both a single raft and two rafts in a background membrane, and the interaction between two rafts as a function of their separation. We find that the chiral penetration depth in the background membrane sets the scale for the range of the interaction. We compare our results with the experimental data and find good agreement for the strength and range of the interaction. Unlike the experiments, however, we do not observe a complete collapse of the data when rescaled by the tilt angle at the raft edge.