Document Detail


A pressure-jump time-resolved X-ray diffraction study of cubic-cubic transition kinetics in monoolein.
MedLine Citation:
PMID:  18257588     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In the past two decades, the geometric pathways involved in the transformations between inverse bicontinuous cubic phases in amphiphilic systems have been extensively theoretically modeled. However, little experimental data exists on the cubic-cubic transformation in pure lipid systems. We have used pressure-jump time-resolved X-ray diffraction to investigate the transition between the gyroid QGII and double-diamond QDII phases in mixtures of 1-monoolein in 30 wt % water. We find for this system that the cubic-cubic transition occurs without any detectable intermediate structures. In addition, we have determined the kinetics of the transition, in both the forward and reverse directions, as a function of pressure-jump amplitude, temperature, and water content. A recently developed model allows (at least in principle) the calculation of the activation energy for lipid phase transitions from such data. The analysis is applicable only if kinetic reproducibility is achieved, at least within one sample, and achievement of such kinetic reproducibility is shown here, by carrying out prolonged pressure-cycling. The rate of transformation shows clear and consistent trends with pressure-jump amplitude, temperature, and water content, all of which are shown to be in agreement with the effect of the shift in the position of the cubic-cubic phase boundary following a change in the thermodynamic parameters.
Authors:
Charlotte E Conn; Oscar Ces; Adam M Squires; Xavier Mulet; Roland Winter; Stephanie M Finet; Richard H Templer; John M Seddon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-02-08
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  24     ISSN:  0743-7463     ISO Abbreviation:  Langmuir     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-03-12     Completed Date:  2008-05-14     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2331-40     Citation Subset:  IM    
Affiliation:
Department of Chemistry, Imperial College London, SW7 2AZ, UK.
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MeSH Terms
Descriptor/Qualifier:
Glycerides / chemistry*
Kinetics
Pressure
Scattering, Small Angle
Time Factors
X-Ray Diffraction
Chemical
Reg. No./Substance:
0/Glycerides; 25496-72-4/monoolein

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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