Issue 46, 2013

Curved fluid membranes behave laterally as effective viscoelastic media

Abstract

The lateral mobility of membrane inclusions is essential in biological processes involving membrane-bound macromolecules, which often take place in highly curved geometries such as membrane tubes or small organelles. Probe mobility is assisted by the lateral fluidity, which is thought to be purely viscous for lipid bilayers and synthetic systems such as polymersomes. In previous theoretical studies, the hydrodynamical mobility is estimated assuming a fixed membrane geometry. However, fluid membranes are very flexible out-of-plane. By accounting for the deformability of the membrane and in the presence of curvature, we show that the lateral motion of an inclusion produces a normal force, which results in a nonuniform membrane deformation. Such a deformation mobilizes the bending elasticity, produces extra lateral viscous and elastic forces, and results in an effective lateral viscoelastic behavior. The coupling between lateral and out-of-plane mechanics is mediated by the interfacial hydrodynamics and curvature. We analyze the frequency and curvature dependent rheology of flexible fluid membranes, and interpret it with a simple four-element model, which provides a background for microrheological experiments. Two key technical aspects of the present work are a new formulation for the interfacial hydrodynamics, and the linearization of the governing equations around a cylindrical geometry.

Graphical abstract: Curved fluid membranes behave laterally as effective viscoelastic media

Article information

Article type
Paper
Submitted
25 Jun 2013
Accepted
21 Aug 2013
First published
21 Aug 2013

Soft Matter, 2013,9, 11033-11045

Curved fluid membranes behave laterally as effective viscoelastic media

M. Rahimi, A. DeSimone and M. Arroyo, Soft Matter, 2013, 9, 11033 DOI: 10.1039/C3SM51748A

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