Hydrodynamics of Multicomponent Vesicles Under Strong Confinement

TL;DR

This study uses numerical simulations to explore the hydrodynamics and membrane behavior of multicomponent vesicles in confined geometries, revealing how lipid phase separation and coarsening are affected by strong confinement, with implications for microfluidic sorting.

Contribution

It introduces a new positive-definite bending modulus parameterization and links vesicle properties to flow conditions during confinement, advancing understanding of vesicle dynamics in microfluidic environments.

Findings

Lipid phase separation occurs in confined vesicles, with stiffer fronts during passage.

Lipid coarsening is halted under strong confinement and resumes after relief.

The model aids in designing microfluidic lipid domain sorting techniques.

Abstract

We numerically investigate the hydrodynamics and membrane dynamics of multicomponent vesicles in two strongly confined geometries. This serves as a simplified model for red blood cells undergoing large deformations while traversing narrow constrictions. We propose a new parameterization for the bending modulus that remains positive for all lipid phase parameter values. For a multicomponent vesicle passing through a stenosis, we establish connections between various properties: lipid phase coarsening, size and flow profile of the lubrication layers, excess pressure, and the tank-treading velocity of the membrane. For a multicomponent vesicle passing through a contracting channel, we find that the lipid always phase separates so that the vesicle is stiffer in the front as it passes through the constriction. For both cases of confinement, we find that lipid coarsening is arrested under strong confinement and proceeds at a high rate upon relief from extreme confinement. The results may be useful for efficient sorting lipid domains using microfluidic flows by controlled release of vesicles passing through strong confinement