Structural parameters and dynamics of lyotropic liquid crystalline phases in hydrated monolinolein
Author(s)
Tang, Tsing-Young Dora
Type
Thesis
Abstract
To date, the stability of inverse bicontinuous cubic phases and the mechanism of lamellar to cubic
transitions are poorly understood due to limited experimental resolution and reproducibility.
Systematic experimental data is imperative for reasonable testing and verification of established
theoretical models in this area. This thesis focuses on two aspects of lyotropic phase behaviour;
the equilibrium behaviour of lyotropic liquid crystalline phases and the transitions between the
equilibrium states.
When monolinolein (ML) is mixed with water it forms a variety of inverse lyotropic phases, for
example the lamellar, inverse bicontinuous phases (QII
G and QII
D) and the inverse hexagonal phase
(HII) which makes this lipid an ideal candidate for study of these phases. The monolinolein
equilibrium phase behaviour has been characterised as a function of pressure, temperature and
hydration using SAXS (small angle X-ray scattering) and the data used to verify the existence of the
pivotal surface in the QII
G phase. Knowing the location of the pivotal surface allows one to calculate
the total energy of these structures.
The second part of this thesis discusses the kinetics of the lamellar to QII
G transition in monolinolein
under limited hydration conditions using the pressure jump time resolved X-ray diffraction
technique. Lamellar to inverse bicontinuous cubic phase transitions are relevant to fundamental
cellular processes such as membrane fusion and fission due to structural similarities of the
mechanisms. The sequence of structural changes observed from kinetic experiments are discussed
in relation to the Stalk Mechanism and the data analysed using a quantitative model.
transitions are poorly understood due to limited experimental resolution and reproducibility.
Systematic experimental data is imperative for reasonable testing and verification of established
theoretical models in this area. This thesis focuses on two aspects of lyotropic phase behaviour;
the equilibrium behaviour of lyotropic liquid crystalline phases and the transitions between the
equilibrium states.
When monolinolein (ML) is mixed with water it forms a variety of inverse lyotropic phases, for
example the lamellar, inverse bicontinuous phases (QII
G and QII
D) and the inverse hexagonal phase
(HII) which makes this lipid an ideal candidate for study of these phases. The monolinolein
equilibrium phase behaviour has been characterised as a function of pressure, temperature and
hydration using SAXS (small angle X-ray scattering) and the data used to verify the existence of the
pivotal surface in the QII
G phase. Knowing the location of the pivotal surface allows one to calculate
the total energy of these structures.
The second part of this thesis discusses the kinetics of the lamellar to QII
G transition in monolinolein
under limited hydration conditions using the pressure jump time resolved X-ray diffraction
technique. Lamellar to inverse bicontinuous cubic phase transitions are relevant to fundamental
cellular processes such as membrane fusion and fission due to structural similarities of the
mechanisms. The sequence of structural changes observed from kinetic experiments are discussed
in relation to the Stalk Mechanism and the data analysed using a quantitative model.
Date Issued
2010-07
Date Awarded
2010-08
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Seddon, John
Templer, Richard
Creator
Tang, Tsing-Young Dora
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)