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Elastic deformations in hexagonal phases studied by small-angle X-ray diffraction and simulationsThis article was submitted as part of a special collection on scattering methods applied to soft matter, marking the 65th birthday of Professor Otto Glatter
Erscheinungsjahr
2011-02
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
In this study we present experimental and theoretical results which concern the deviations from circularity of the pivotal plane in the inverse hexagonal phases (H
II
) of phospholipidself-assemblies. Due to packing constraints, the cross-section of the polar/apolar interface deviates from a circle, which we studied in minute detail by analysing small-angle X-ray diffraction data of dioleoyl-phosphatidylethanolamine (DOPE) and stearoyl-oleoyl-phosphatidylethanolamine (SOPE), respectively. On this structural basis, Monte Carlo (MC) simulated annealing variations of the free energy were carried out, both on the formation of the H
II
-phase and on the particular shape of the cross-section in the H
II
-phase. The equilibrium of the H
II
-phase pivotal plane contour and the corresponding values of the mean intrinsic curvature,
H
m
, and the hydrocarbon chain stiffness,
τ
, were determined from MC calculations. The results of these calculations were tested by solving the corresponding system of non-linear differential equations derived using variational calculus. Here our main aim is to predict the range of possible values of
H
m
and
τ
. Comparing the measured structural data with predictions from MC calculations including lipid anisotropy, and accounting for the elastic deformations of the pivotal plane allowed us to determine a relationship between the bending deformation and stretching of hydrocarbon chains.
Theoretical insights taking into account the non-circular geometry of the H
II
-phase cross-section and anisotropy of phospholipids were validated by small-angle X-ray diffraction.
Sprache
Englisch
Identifikatoren
ISSN: 1463-9076
eISSN: 1463-9084
DOI: 10.1039/c0cp01187h
Titel-ID: cdi_rsc_primary_c0cp01187h
Format
–
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