DOPC-DOPE composition dependent Lα-HII thermotropic phase transition: SAXD study

Chem Phys Lipids. 2016 Jun:198:46-50. doi: 10.1016/j.chemphyslip.2016.05.004. Epub 2016 May 11.

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.

Keywords: Cubic phase; Dioleoylphosphatidylcholine; Dioleoylphosphatidylethanolamine; Inverse hexagonal phase; Lamellar phase; Small-angle X-ray diffraction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Phase Transition*
  • Phosphatidylcholines / chemistry*
  • Phosphatidylethanolamines / chemistry*
  • Scattering, Small Angle
  • Transition Temperature
  • X-Ray Diffraction

Substances

  • Phosphatidylcholines
  • Phosphatidylethanolamines
  • 1,2-dielaidoylphosphatidylethanolamine
  • 1,2-oleoylphosphatidylcholine