title: The component group structure of DPPC bilayers obtained by specular neutron reflectometry.
abstract: Specular neutron reflectometry was measured on a floating bilayer system consisting of 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine deposited over a 1,2-dibehenoyl-sn-glycero-3-phosphocholine bilayer at 25 and 55 °C. The internal structure of lipid bilayers was described by a one-dimensional neutron scattering length density profile model, originally developed for the evaluation of small-angle scattering data. The reflectivity data from the supported bilayer were evaluated separately and used further as constraints in modeling the floating bilayer reflectivity curves. The model reflectivity curves successfully describe the experimental reflectivities of the supported bilayer in the gel phase and the floating bilayer system in the liquid-crystalline phase. The results yield an internal structure of a deposited bilayer and a floating bilayer on the level of component groups of lipid molecules. The obtained structure of the floating d62-diC16:0PC bilayer displays high resemblance of the bilayer structure in the form of unilamellar vesicles. At the same time, however, the results show differences in comparison to unilamellar vesicle bilayers, most likely due to the undulations of supported bilayers.
authors.affiliation: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, Odbojárov 10, SK-832 32 Bratislava, Slovakia. belicka@fpharm.uniba.sk.
authors.forename: Michal
authors.initials: M
authors.lastname: Belička
authors.forename: Yuri
authors.initials: Y
authors.lastname: Gerelli
authors.forename: Norbert
authors.initials: N
authors.lastname: Kučerka
authors.forename: Giovanna
authors.initials: G
authors.lastname: Fragneto
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D033363:Neutron Diffraction; D010713:Phosphatidylcholines / Q000737:chemistry*; D053838:Scattering, Small Angle; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D053835:Unilamellar Liposomes; C097424:dibehenoylphosphatidylcholine; D004134:Dimyristoylphosphatidylcholine