title: Systematic variation of gel-phase texture in phospholipid membranes.
abstract: The tilted gel phase of lipid bilayers can display in-plane orientational texture due to long-range alignment of the molecular director. We explore systematic variations of texture defects in a series of binary phospholipid membranes. Using polarized two-photon fluorescence microscopy, the texture pattern of single domains is revealed. The appearance of a central vortex-type defect in each domain correlates with a particular range of hydrophobic mismatch values h > 1 nm at the domain border while domains with h < 1 nm correlate with uniformly aligned texture. The central vortex defect is characterized by a defect angle, indicating its bend or splay nature. Using image analysis, we measure the defect angle and find that it has primarily bend character for small mismatch values (h ≈ 1 nm) and primarily splay nature for larger values of h. For domains containing a vortex, the domain shape is decoupled from the texture while for uniformly textured domains there is a preferred texture orientation of ≃45° along the domain border. The results establish a foundation for understanding texture phenomena in compositionally complex membranes.
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, †Department of Physics Chemistry and Pharmacy and ‡Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Jes
authors.initials: J
authors.lastname: Dreier
authors.forename: Jonathan
authors.initials: J
authors.lastname: Brewer
authors.forename: Adam Cohen
authors.initials: AC
authors.lastname: Simonsen
mesh_terms: D008051:Lipid Bilayers / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D010743:Phospholipids / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D010743:Phospholipids