title: Tube formation and spontaneous budding in a fluid charged membrane.
abstract: We determine the equations governing the equilibrium shape of an axially symmetric charged fluid membrane under the action of an external field. We consider that the charges are free to diffuse along the membrane, and we neglect the effect of screening counterions. By numerically integrating these equations for a membrane spread across a hole by a constant tension, we show that there exists a threshold electric field above which an infinitely long tube can be pulled. The threshold field for pulling a tube decreases as the surface charge density of the membrane increases, reaching zero at a finite critical value. Above this critical density of charge, the membrane spontaneously buds, in the absence of externally applied fields, because of the electrostatic repulsion of its charges.
authors.affiliation: Matière et Systèmes Complexes, UMR 7057 CNRS & Université Paris 7, Denis Diderot, Case 7056, 2 place Jussieu, F-75251 Paris Cedex 05, France. galatola@ccr.jussieu.fr
authors.forename: P
authors.initials: P
authors.lastname: Galatola
mesh_terms: D022081:Cell Surface Extensions / Q000737:chemistry* / Q000528:radiation effects; D003198:Computer Simulation; D004548:Elasticity / Q000528:radiation effects; D004574:Electromagnetic Fields; D008051:Lipid Bilayers / Q000737:chemistry* / Q000528:radiation effects; D008560:Membrane Fluidity / Q000528:radiation effects; D008564:Membrane Potentials / Q000528:radiation effects*; D008567:Membranes, Artificial; D008956:Models, Chemical; D008958:Models, Molecular; D055672:Static Electricity; D013314:Stress, Mechanical
chemical_list: D008051:Lipid Bilayers; D008567:Membranes, Artificial