DYNAMICS OF THE LIPID-BILAYER MEMBRANE TAKING A VESICLE SHAPE

The lipid-bilayer membrane is treated as a two-dimensional viscous fluid with a restoring force against bending. We present a general theory of the dynamics of such a fluid, and as an application we calculate the damping coefficient of slow overdamped motion of the membrane which takes a spherical-vesicle shape in equilibrium. Discussions of the in-plane compression modulus and the membrane continuity in some recent theories are inappropriate for the lipid-bilayer membrane. We also find that membrane viscosity mu is important as compared to viscosities, muBAR and mu, of the inner fluid and the outer fluid unless mu is much smaller than murBAR and mur0 (r0 being the vesicle radius).