Diffusion and Binding in Polymerized Bicontinuous Cubic Phases

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ABSTRACTCTS-9816826David O'BrienU. of ArizonaNatural and synthetic polar lipids can form a variety of hydrated nonlamellar phases, including the inverted hexagon (HII) and inverted bicontinuous cubic (QII) phases. Lipids that readily form one or more of these nonlamellar phases are sometimes termed polymorphic lipids. Appropriately designed polymerizable polymorphic lipids can be successfully used to form either of these nonlamellar phases and stabilize them via crosslinking polymerization. The bicontinuous cubic morphologies consist of curved lipid bilayers that separate interpentrating water channels. The principal investigator's has introduced a successful strategy for the polymerization of these nonlamellar phases, that retains their morphology and stabilizes the assembly in a manner that enhances both the temperature range and resistance to organic solvents. Thus the lipid domains can be converted to poly(lipid) with a wide range of polymer properties, while leaving the water domains unperturbed for further elaboration. The interpentrating networks of the polymerized QII phases suggests potential applications of these organic zeolites, which take full advantage of the lipid membrane surface for the localization of reagents, the immobilization of antibody fragments or abenzymes, or the incorporation of proteins for chemcial or biological conversions, diagnostic, and/or separation applications. The objective of this proposal is to characterize the effect of molecular size on the diffusion of water-soluble macromolecules within the water channels of polymerized QII phases. Macromolecular diffusion will be experimentally determined using pulsed field gradient NMR techniques. The materials for the formation and stabilization of QII phases will come from a family of readily synthesized polymerizable lipids. This is a terminal grant for one year.