title: Bending Rigidities and Interdomain Forces in Membranes with Coexisting Lipid Domains.
abstract: To precisely quantify the fundamental interactions between heterogeneous lipid membranes with coexisting liquid-ordered (Lo) and liquid-disordered (Ld) domains, we performed detailed osmotic stress small-angle x-ray scattering experiments by exploiting the domain alignment in raft-mimicking lipid multibilayers. Performing a Monte Carlo-based analysis allowed us to determine with high reliability the magnitude and functional dependence of interdomain forces concurrently with the bending elasticity moduli. In contrast to previous methodologies, this approach enabled us to consider the entropic undulation repulsions on a fundamental level, without having to take recourse to crudely justified mean-field-like additivity assumptions. Our detailed Hamaker-coefficient calculations indicated only small differences in the van der Waals attractions of coexisting Lo and Ld phases. In contrast, the repulsive hydration and undulation interactions differed significantly, with the latter dominating the overall repulsions in the Ld phase. Thus, alignment of like domains in multibilayers appears to originate from both, hydration and undulation repulsions.
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kollmitzer
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Heftberger
authors.affiliation: Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia; Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; Department of Physics, University of Massachusetts, Amherst, Massachusetts.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Podgornik
authors.affiliation: Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania.
authors.forename: John F
authors.initials: JF
authors.lastname: Nagle
authors.affiliation: University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria. Electronic address: georg.pabst@uni-graz.at.
authors.forename: Georg
authors.initials: G
authors.lastname: Pabst
mesh_terms: D001696:Biomechanical Phenomena; D019277:Entropy; D008051:Lipid Bilayers / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry*; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D008051:Lipid Bilayers