The effect of curvature and topology on membrane hydrodynamics

¹  Department of Chemistry and Biochemistry, University of California - Los Angeles, CA 90095, USA
²  Department of Physics, University of Massachusetts - Amherst, MA 01003, USA
³  Department of Physics, Harvard University - Cambridge, MA 02138, USA
⁴  School of Physics, The University of Edinburgh - Edinburgh EH9 3JZ, UK, EU
⁵  California Nanosystems Institute, University of California - Los Angeles, CA 90095, USA

Received: 11 July 2008
Accepted: 5 October 2008

Abstract

We study the mobilities of point-like and extended objects (rods) on a spherical membrane to show how these quantities are modified in a striking manner by the curvature and topology of the membrane. We also present theoretical calculations and experimental measurements of the membrane fluid velocity field around a moving rod bound to the crowded interface of a water-in-oil droplet. By using different droplet sizes, membrane viscosities, and rod lengths, we show that the viscosity mismatch between the interior and exterior fluids leads to a suppression of the fluid flow on small droplets that cannot be captured by the flat-membrane predictions.