title: Hydrophobic Mismatch Triggering Texture Defects in Membrane Gel Domains.
abstract: The orientational texture of gel-phase lipid bilayers is a phenomenon that can structure membrane domains. Using two-photon polarized fluorescence microscopy and image analysis, we map the lateral variation of the lipid orientation (the texture) in single domains. With this method, we uncover a lipid-induced transition between vortex and uniform textures in binary phospholipid bilayers. By tuning the lipid composition, the hydrophobic mismatch at the domain boundary can be varied systematically as monitored by AFM. Low hydrophobic mismatch correlates with domains having uniform texture, while higher mismatch values correlate with a vortex-type texture. The defect pattern created during early growth persists in larger domains, and a minimal model incorporating the anisotropic line tension and the vortex energy can rationalize this finding. The results suggest that the lipid composition and the domain nucleation process are critical factors that determine the texture pattern of membrane domains.
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, ‡ Department of Biochemistry and Molecular Biology, and ¶Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Jes
authors.initials: J
authors.lastname: Dreier
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, ‡ Department of Biochemistry and Molecular Biology, and ¶Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Brewer
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, ‡ Department of Biochemistry and Molecular Biology, and ¶Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Adam Cohen
authors.initials: AC
authors.lastname: Simonsen
keywords: atomic force microscopy; image analysis; line tension; lipid bilayer; orientational texture; polarized fluorescence microscopy