Engineering bicontinuous cubic structures at the nanoscale—the role of chain splay

Abstract

Many amphiphile-water mixtures will self-assemble into three-dimensional soft condensed structures known as inverse bicontinuous cubic phases. These structures are found in nature and have applications in nanotechnology. Here we show that by systematically varying amphiphile chain splay, we are able to control the relative stability of the inverse bicontinuous phases in a homologous series of monoglycerides in a predictable manner. In particular, we demonstrate that decreasing chain splay leads to the appearance of the primitive bicontinuous cubic phase while increasing chain splay reduces the channel size of the remaining two bicontinuous phases and tends to destabilize them with respect to the more curved inverse micellar and inverse hexagonal phases. These observations are consistent with a model in which the energetic stability of these phases is principally governed by the competing demands for homogeneous interfacial curvature and uniform chain packing and points to straightforward rules for engineering these self-assembling nanostructures.

Pressure effects on a protein–lipid model membrane

“…This characteristic is very common in lipid systems in excess water as the lipid molecules display increased chain splay 30 with increasing temperature, while the reverse trend is observed when 5 hydrostatic pressure is applied. The latter thereby decreases the membrane curvature and thus tends to swell the lyotropic phase, drawing in additional water.…”

Hierarchically Organized Systems Based on Liquid Crystalline Phases

“…In the case of shorter C -chain oils, such as decane, the transfer of oil to cubosomes was found to be much faster than the transfer of monoglycerides to the emulsion droplets, but for less soluble oils the trend was reversed. Thus its effective chain length is reduced (14.23 Å for pure ML, according to unpublished results) (Kulkarni et al, 2010c ). 6.10 ) where the monoglyceride (18 C -chain lipid) behaves like an alkane with about 15.3 carbons in such a compositional ripening.…”

“…The type 1 of fundamental assembly that forms depends on the molecular shape of the amphiphile, as shown in Figure 6.1 . The lipid molecular shape can also be engineered by altering the unsaturation (number and location), which thus provides an opportunity to fi nely control the lipid phase behavior (Kulkarni et al, 2010c ). Lipids or block copolymers with more hydrophobic character usually form type 2 (inverse) micelles, which are the major focus of the present work.…”

Lipid Self-Assemblies and Nanostructured Emulsions for Cosmetic Formulations

“…On conventional lipid-water phase diagrams, the bicontinuous cubic phases are generally observed at higher water fractions as compared to lamellar phases [46][47][48]. This also means that cubic phases show stronger water holding capacity than lamellar nanostructures.…”