Persistent Collective Motion of a Dispersing Membrane Domain

TL;DR

This paper investigates how membrane flows cause a dispersing membrane domain to maintain collective motion longer than expected, revealing slow decay of the center of mass diffusion and implications for membrane heterogeneity stability.

Contribution

It demonstrates that quasi-two-dimensional membrane flows couple inclusion motions, prolonging collective movement and causing weak sub-diffusion, supported by analytical and simulation results.

Findings

Membrane flows couple inclusion motions, extending collective movement.

The center of mass diffusion coefficient decays slowly over time.

The effect impacts the stability of nano-scale membrane heterogeneities.

Abstract

We study the Brownian motion of an assembly of mobile inclusions embedded in a fluid membrane. The motion includes the dispersal of the assembly, accompanied by the diffusion of its center of mass. Usually, the former process is much faster than the latter, since the diffusion coefficient of the center of mass is inversely proportional to the number of particles. However, in the case of membrane inclusions, we find that the two processes occur on the same time scale, thus prolonging significantly the lifetime of the assembly as a collectively moving object. This effect is caused by the quasi-two-dimensional membrane flows, which couple the motions even of the most remote inclusions in the assembly. The same correlations also cause the diffusion coefficient of the center of mass to decay slowly with time, resulting in weak sub-diffusion. We confirm our analytical results by Brownian dynamics simulations with flow-mediated correlations. The effect reported here should have implications for the stability of nano-scale membrane heterogeneities.