Equilibrium budding and vesiculation in the curvature model of fluid lipid vesicles

Ling Miao, Bertrand Fourcade, Madan Rao, Michael Wortis, and R. K. P. Zia
Phys. Rev. A 43, 6843 – Published 1 June 1991
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Abstract

According to a model introduced by Helfrich [Z. Naturforsch. 28c, 693 (1973)], the shape of a closed lipid vesicle is determined by minimization of the total bending energy at fixed surface area and enclosed volume. We show that, in the appropriate regime, this model predicts both budding (the eruption of a satellite connected to the parent volume via a neck) and vesiculation (the special case when the neck radius goes to zero). Vesiculation occurs when the minimum is located at a boundary in the space of configurations. Successive vesiculations produce multiplets, in which the minimum-energy configuration consists of several bodies coexisting through infinitesimal necks. We study the sequence of shapes and shape transitions followed by a spherical vesicle of radius RV, large on the scale R0 set by the spontaneous curvature, as its area A increases at constant volume V=4πRV3/3. Such a vesicle periodically sheds excess area into a set of smaller spheres with radii comparable to R0. We map out this (shape) phase diagram at large volume. In this region the phase diagram is dominated by multiplets and reflects the details of the shedding process. The overall effect of successive vesiculations is to reduce the energy from a quantity of order RV2 down to zero or near zero when the area reaches 3V/R0; however, the decrease is not uniform and the energy E(A,V) is not convex.

  • Received 7 November 1990

DOI:https://doi.org/10.1103/PhysRevA.43.6843

©1991 American Physical Society

Authors & Affiliations

Ling Miao, Bertrand Fourcade, Madan Rao, and Michael Wortis

  • Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6

R. K. P. Zia

  • Department of Physics and Center for Stochastic Processes in Science Engineering, Virgina Polytechnic Institute and State University, Blacksburg, Virginia 24061-0435

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Vol. 43, Iss. 12 — June 1991

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