Lipid bilayer membrane with atomic step structure: supported bilayer on a step-and-terrace TiO2(100) surface

Langmuir. 2008 Oct 21;24(20):11567-76. doi: 10.1021/la801080f. Epub 2008 Sep 12.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Lipid Bilayers* / chemistry
  • Lipids / chemistry
  • Membranes, Artificial
  • Microscopy, Atomic Force / methods
  • Microscopy, Fluorescence / methods
  • Molecular Conformation
  • Oxygen / chemistry
  • Phospholipids / chemistry
  • Substrate Specificity
  • Surface Properties
  • Titanium / chemistry*

Substances

  • Lipid Bilayers
  • Lipids
  • Membranes, Artificial
  • Phospholipids
  • titanium dioxide
  • Titanium
  • Oxygen