A Pressure-Jump Time-Resolved X-ray Diffraction Study of Cubic-Cubic Transition Kinetics in Monoolein
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- 作者：Charlotte E. Conn ; Oscar Ces ; Adam M. Squires ; Xavier Mulet ; Roland Winter ; Stephanie M. Finet ; Richard H. Templer ; John M. Seddon
- 刊名：Langmuir
- 出版年：2008
- 出版时间：March 18, 2008
- 年：2008
- 卷：24
- 期：6
- 页码：2331 - 2340
- 全文大小：407K
- 年卷期：v.24,no.6(March 18, 2008)
- ISSN：1520-5827
文摘
In the past two decades, the geometric pathways involved in the transformations between inverse bicontinuous cubicphases in amphiphilic systems have been extensively theoretically modeled. However, little experimental data existson the cubic-cubic transformation in pure lipid systems. We have used pressure-jump time-resolved X-ray diffractionto investigate the transition between the gyroid 
and double-diamond 
phases in mixtures of 1-monoolein in30 wt % water. We find for this system that the cubic-cubic transition occurs without any detectable intermediatestructures. 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 leastin principle) the calculation of the activation energy for lipid phase transitions from such data. The analysis is applicableonly if kinetic reproducibility is achieved, at least within one sample, and achievement of such kinetic reproducibilityis shown here, by carrying out prolonged pressure-cycling. The rate of transformation shows clear and consistent trendswith pressure-jump amplitude, temperature, and water content, all of which are shown to be in agreement with theeffect of the shift in the position of the cubic-cubic phase boundary following a change in the thermodynamicparameters.
and double-diamond phases in mixtures of 1-monoolein in30 wt % water. We find for this system that the cubic-cubic transition occurs without any detectable intermediatestructures. 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 leastin principle) the calculation of the activation energy for lipid phase transitions from such data. The analysis is applicableonly if kinetic reproducibility is achieved, at least within one sample, and achievement of such kinetic reproducibilityis shown here, by carrying out prolonged pressure-cycling. The rate of transformation shows clear and consistent trendswith pressure-jump amplitude, temperature, and water content, all of which are shown to be in agreement with theeffect of the shift in the position of the cubic-cubic phase boundary following a change in the thermodynamicparameters.