title: Nano-meter-sized domain formation in lipid membranes observed by small angle neutron scattering.
abstract: Using a contrast matching technique of small angle neutron scattering (SANS), we have investigated a phase separation to liquid-disordered and liquid-ordered phases on ternary small unilamellar vesicles (SUVs) composed of deuterated-saturated, hydrogenated-unsaturated phosphatidylcholine lipids and cholesterol, where the equilibrium size of these domains is constrained to less than 10nm by the system size. Below a miscibility temperature, we observed characteristic scattering profiles with a maximum, indicating the formation of nano-meter-sized domains on the SUVs. The observed profiles can be described by a multi-domain model rather than a mono-domain model. The nano-meter-sized domain is agitated by thermal fluctuations and eventually ruptured, which may result in the multi-domain state. The kinetically trapped nano-meter-sized domains grow to a mono-domain state by decreasing temperature. Furthermore, between the miscibility and disorder-order transition temperature of saturated lipid, the integrated SANS intensity increased slightly, indicating the formation of nano-meter-sized heterogeneity prior to the domain nucleation.
authors.affiliation: Department of Physics, Ochanomizu University, 112-8610, Bunkyo, Tokyo, Japan. masui.tomomi@jaea.go.jp
authors.forename: T
authors.initials: T
authors.lastname: Masui
authors.forename: N
authors.initials: N
authors.lastname: Urakami
authors.forename: M
authors.initials: M
authors.lastname: Imai
mesh_terms: D008563:Membrane Lipids / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry*; D036103:Nanotechnology; D033363:Neutron Diffraction; D053838:Scattering, Small Angle; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D008563:Membrane Lipids; D053835:Unilamellar Liposomes