title: Fluctuation dynamics of bilayer vesicles with intermonolayer sliding: experiment and theory.
abstract: The presence of coupled modes of membrane motion in closed shells is extensively predicted by theory. The bilayer structure inherent to lipid vesicles is suitable to support hybrid modes of curvature motion coupling membrane bending with the local reorganization of the bilayer material through relaxation of the dilatational stresses. Previous experiments evidenced the existence of such hybrid modes facilitating membrane bending at high curvatures in lipid vesicles [Rodríguez-García, R., Arriaga, L.R., Mell, M., Moleiro, L.H., López-Montero, I., Monroy, F., 2009. Phys. Rev. Lett. 102, 128201.]. For lipid bilayers that are able to undergo intermonolayer sliding, the experimental fluctuation spectra are found compatible with a bimodal schema. The usual tension/bending fluctuations couple with the hybrid modes in a mechanical interplay, which becomes progressively efficient with increasing vesicle radius, to saturate at infinity radius into the behavior expected for a flat membrane. Grounded on the theory of closed shells, we propose an approximated expression of the bimodal spectrum, which predicts the observed dependencies on the vesicle radius. The dynamical features obtained from the autocorrelation functions of the vesicle fluctuations are found in quantitative agreement with the proposed theory.
authors.affiliation: Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
authors.forename: Michael
authors.initials: M
authors.lastname: Mell
authors.affiliation: Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain; Physikalische Chemie I, Univeristät Bayreuth, Universitätsstraße 30, D-95447 Bayreuth, Germany.
authors.forename: Lara H
authors.initials: LH
authors.lastname: Moleiro
authors.affiliation: Physikalische und Biophysikalische Chemie I, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Hertle
authors.affiliation: Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
authors.forename: Iván
authors.initials: I
authors.lastname: López-Montero
authors.affiliation: Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Cao
authors.affiliation: TOF/HR Group, Institut Laue Langevin, 6 Rue Jules Horowitz, BP156, F-38042 Grenoble Cedex 9, France.
authors.forename: Peter
authors.initials: P
authors.lastname: Fouquet
authors.affiliation: Physikalische und Biophysikalische Chemie I, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hellweg
authors.affiliation: Departamento de Química Física I, Universidad Complutense de Madrid, E-28040 Madrid, Spain. Electronic address: monroy@quim.ucm.es.
authors.forename: Francisco
authors.initials: F
authors.lastname: Monroy
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D013696:Temperature; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000378:metabolism
chemical_list: D008051:Lipid Bilayers; D053835:Unilamellar Liposomes; D004134:Dimyristoylphosphatidylcholine
keywords: Bending; Friction; Lipid; Membrane