title: Lipid bilayer membrane with atomic step structure: supported bilayer on a step-and-terrace TiO2(100) surface.
abstract: The formation of a supported planar lipid bilayer (SPLB) and its morphology on step-and-terrace rutile TiO 2(100) surfaces were investigated by fluorescence microscopy and atomic force microscopy. The TiO 2(100) surfaces consisting of atomic steps and flat terraces were formed on a rutile TiO 2 single-crystal wafer by a wet treatment and annealing under a flow of oxygen. An intact vesicular layer formed on the TiO 2(100) surface when the surface was incubated in a sonicated vesicle suspension under the condition that a full-coverage SPLB forms on SiO 2, as reported in previous studies. However, a full-coverage, continuous, fluid SPLB was obtained on the step-and-terrace TiO 2(100) depending on the lipid concentration, incubation time, and vesicle size. The SPLB on the TiO 2(100) also has step-and-terrace morphology following the substrate structure precisely even though the SPLB is in the fluid phase and an approximately 1-nm-thick water layer exists between the SPLB and the substrate. This membrane distortion on the atomic scale affects the phase-separation structure of a binary bilayer of micrometer order. The interaction energy calculated including DLVO and non-DLVO factors shows that a lipid membrane on the TiO 2(100) gains 20 times more energy than on SiO 2. This specifically strong attraction on TiO 2 makes the fluid SPLB precisely follow the substrate structure of angstrom order.
authors.affiliation: Division of Biomolecular Sensing, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan. tero@ims.ac.jp
authors.forename: Ryugo
authors.initials: R
authors.lastname: Tero
authors.forename: Toru
authors.initials: T
authors.lastname: Ujihara
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Urisu
mesh_terms: D000327:Adsorption; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D013379:Substrate Specificity; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D008055:Lipids; D008567:Membranes, Artificial; D010743:Phospholipids; C009495:titanium dioxide; D014025:Titanium; D010100:Oxygen