title: DOPC-DOPE composition dependent Lα-HII thermotropic phase transition: SAXD study.
abstract: The structural polymorphism and parameters of lyotropic phases formed in the mixed dioleoylphosphatidylcholine-dioleoylphosphatidylethanolamine (DOPC-DOPE) system upon heating and varying DOPC:DOPE composition were studied by means of small-angle X-ray diffraction (SAXD). In the temperature range 5-80°C a sequence of fluid lamellar Lα - inverse hexagonal HII - inverse cubic QII phases was detected at DOPE mole fractions XDOPE≥0.65. A superposition of two bicontinuous cubic QII phases of Pn3m and Ia3d space groups was identified. The Lα to HII phase transition temperature, the onset of the QII phase formation, as well as the lattice spacings of the Lα and HII phases were found to decrease with rising DOPE content. Moreover, evidence of structural rearrangement during the Lα to HII phase transition is given and change of transition mechanism with varying XDOPE is suggested.
authors.affiliation: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia. Electronic address: klacsova@fpharm.uniba.sk.
authors.forename: M
authors.initials: M
authors.lastname: Klacsová
authors.affiliation: Department of Biological Nanochemistry, Hungarian Science Academy, Budapest, Hungary.
authors.forename: A
authors.initials: A
authors.lastname: Bóta
authors.affiliation: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia.
authors.forename: P
authors.initials: P
authors.lastname: Balgavý
mesh_terms: D044367:Phase Transition; D010713:Phosphatidylcholines / Q000737:chemistry*; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D053838:Scattering, Small Angle; D044366:Transition Temperature; D014961:X-Ray Diffraction
chemical_list: D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C020888:1,2-dielaidoylphosphatidylethanolamine; C017251:1,2-oleoylphosphatidylcholine
keywords: Cubic phase; Dioleoylphosphatidylcholine; Dioleoylphosphatidylethanolamine; Inverse hexagonal phase; Lamellar phase; Small-angle X-ray diffraction