Budding and domain shape transformations in mixed lipid films and bilayer membranes.
We study the stability and shapes of domains with spontaneous curvature in fluid films and membranes, embedded in a surrounding membrane with zero spontaneous curvature. These domains can result from the inclusion of an impurity in a fluid membrane or from phase separation within the membrane. We show that for small but finite line and surface tensions and for finite spontaneous curvatures, an equilibrium phase of protruding circular domains is obtained at low impurity concentrations. At higher concentrations, we predict a transition from circular domains, or caplets, to stripes. In both cases, we calculate the shapes of these domains within the Monge representation for the membrane shape. With increasing line tension, we show numerically that there is a budding transformation from stable protruding circular domains to spherical buds. We calculate the full phase diagram and demonstrate two triple points of, respectively, bud-flat-caplet and flat-stripe-caplet coexistence.
Harden
J L
JL
Department of Chemical Engineering, Johns Hopkins University, Baltimore, Maryland 21218-2689, USA. harden@jhu.edu
Mackintosh
F C
FC
Olmsted
P D
PD
D001703:Biophysics / Q000379:methods*; D008051:Lipid Bilayers; D008055:Lipids / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry*; D008566:Membranes / Q000737:chemistry; D015233:Models, Statistical; D008962:Models, Theoretical; D016011:Normal Distribution
D008051:Lipid Bilayers; D008055:Lipids; D046911:Macromolecular Substances; D008563:Membrane Lipids