Kinetics and Mechanism of the Lamellar to Gyroid Inverse Bicontinuous Cubic Phase Transition

Squires, Adam M.; Templer, Richard H.; Seddon, John M.; Woenckhaus, J.; Winter, Roland; Finet, Stéphanie; Theyencheri, Narayanan

doi:10.1021/la0259555

Cited by 71 publications

(74 citation statements)

References 40 publications

(76 reference statements)

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“…While these processes proved very active, with the stalk arrangements morphing continuously, the instantaneous in-plane distributions of stalks and holes were generally hexagonal, as suggested in a previous experimental assessment of this transition [18]. By timestep 800,000 (Fig 2d), the original planar topology was significantly altered, with numerous stalks linking the remnants of the original planes.…”

supporting

confidence: 58%

Entropy-Driven Formation of the Gyroid Cubic Phase

Ellison

Michel

Barmes³

et al. 2006

Phys. Rev. Lett.

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supporting

confidence: 58%

Entropy-Driven Formation of the Gyroid Cubic Phase

Ellison

Michel

Barmes³

et al. 2006

Phys. Rev. Lett.

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“…These dynamical features are not exclusive to ME; both the decrease in lattice parameter of the lamellar phase and the existence of an intermediate swollen cubic phase have been previously noted for several other amphiphiles including monomyristolein (unpublished data), 1-monoolein (MO) [24], and 2:1 Lauric Acid (LA) and Di-laurylphosphatidylcholine (DLPC) (2LA-DLPC) mixtures [16]. Additionally, for the systems monomyristolein in excess water and monoelaidin and monoolein under limited water conditions (unpublished data) we again observe a highly specific final lattice parameter of the lamellar phase and a strong dependence of the rate of shrinking on pressurejump amplitude.…”

Section: IImentioning

confidence: 66%

“…To date the most convincing evidence has been structural evidence that is consistent with the existence of fusion stalks [14]. As for the structural dynamics, a limited amount of experimental work has been carried out on the lamellar to inverse bicontinuous cubic phase transition [15][16][17][18][19]. The major problem to date with these dynamical studies is the lack of reproducibility in results [20,21].…”

mentioning

confidence: 99%

Dynamics of Structural Transformations between Lamellar and Inverse Bicontinuous Cubic Lyotropic Phases

et al. 2006

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The liquid crystalline lamellar (L ) to double-diamond inverse bicontinuous cubic (Q D II ) phase transition for the amphiphile monoelaidin in excess water exhibits a remarkable sequence of structural transformations for pressure or temperature jumps. Our data imply that the transition dynamics depends on a coupling between changes in molecular shape and the geometrical and topological constraints of domain size. We propose a qualitative model for this coupling based on theories of membrane fusion via stalks and existing knowledge of the structure and energetics of bicontinuous cubic phases. DOI: 10.1103/PhysRevLett.96.108102 PACS numbers: 87.16.Dg, 61.10.Eq, 87.17.Ee, 64.70.Md Lyotropic liquid crystalline phases form when amphiphilic molecules are mixed with a polar solvent [1,2]. The many structures they can adopt, their complex phase behavior and their energetics have received a great deal of attention over the past half century. Much is now understood about their equilibrium behavior and this has informed the development of surfactant technologies and our understanding of how amphiphiles in biological membranes can control biochemical activity [3,4]. By comparison the study of the nonequilibrium structure and dynamics of lyotropic liquid crystalline systems is in its infancy and little is understood about the mechanisms by which one phase transforms into another [5,6]. Understanding the dynamics of lyotropic phase transformations is of practical interest for applications where amphiphilic materials are processed and of relevance in biological systems where membrane fusion or division occurs.The present work focuses on a phase transition where membrane fusion occurs: the fluid lamellar to inverse bicontinuous cubic phase transition, Fig. 1. Models for the process of membrane fusion between apposed lipid bilayers have been proposed by a number of groups [7][8][9]. All rely on the formation of transient lipid contacts known as stalks, which subsequently break through to form the beginnings of the tubular connections that are the fundamental connecting element in the inverse bicontinuous cubic phases. Recent theoretical models of the structure and energy of the stalk have incorporated both elastic energy, accounting for the splay, saddle splay, and tilt deformations of the membrane, as well as hydration repulsion acting between the apposing membranes [10 -12]. The models have been used to estimate the energy of stalk formation and mesoscopic models have been used to simulate the entire fusion process [13]. However, very few measurements have been made to test these models. To date the most convincing evidence has been structural evidence that is consistent with the existence of fusion stalks [14]. As for the structural dynamics, a limited amount of experimental work has been carried out on the lamellar to inverse bicontinuous cubic phase transition [15][16][17][18][19]. The major problem to date with these dynamical studies is the lack of reproducibility in results [20,21]. FIG. 1 (color online). In these im...

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“…A further innovation of this system is the use of a high pressure reservoir on the pump side of the jumping valves; this allows larger amplitude pressure jumps to be performed. The specifications of this pressure system have set the bench mark for more recent soft condensed matter pressure cells and this system has facilitated some extremely exciting lipid experiments (Conn et al, , 2008Eisenblatter, 2006;Jeworrek et al, 2008;Kraineva et al, 2005;Squires et al, 2000Squires et al, , 2002.…”

Section: Soft Condensed Matter Cells For Small Angle X-ray Scatteringmentioning

confidence: 99%