Polymerization and Domain Formation in Lipid Assemblies

Abstract

Lipid assemblies are arrays of noncovalently associated amphiphiles, i.e. supramolecular assemblies. They may be classified as supported or self-supported assmeblies. The advent of methods to polymerize these supramolecular assemblies has opened up opportunities for the creation of new materials. This review emphasizes the interaction of polymerization and lipid domain formation within supramolecular assemblies. The polymerization of amphiphilic assemblies can "lock in" preexisting lipid domains or create lipid domains from random mixtures depending on the nature of the polymerizable amphiphile. Lipid diacetylenes or fluorinated lipids provide a convenient means to form an unpolymerized immiscible mixture of reactive and nonreactive lipids in monolayers or bilayers. In contrast the polymerization of dienoyl-, sorbyl-, or acryloyl-substituted lipids can effectively induce the phase separation of unreactive lipids from the growing polymeric domains. Polymerization-induced lipid domains can endow bilayer vesicles with latent instability sites or can be used to concentrate membrane-associated electron or energy transfer cofactors. These polymeric materials suggest new approaches to the delivery of reagents as well as the transduction of light energy.