Polymerized Bicontinuous Cubic Lipid Assemblies

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Several classes of biological and synthetic lipids from hydrated membrane systems that display a variety of lamellar and nonlamellar phases as a function of temperature, pressure and concentration. This proposal focuses on inverted cubic phases which are found between lamellar and hexagonal phases. The inverted cubic phases of interest are those which are bicontinuous with respect to the polar (aqueous) and nonpolar (lipid) phases. The interpenetrating network of aqueous channels and lipid surfaces of the bicontinous cubic phase permit the passage of water soluble species through the structure. These free standing structures have the morphology of zeolite only with biocompatible lipid surfaces, and as such can be envisioned to have many applications in bioseparations and membrane reactor techniques. Once formed, cubic lipid phases are sometimes stable for weeks, however their temperature range is usually narrow and frequently occurs at temperatures higher than room or even physiological temperatures. The PI has pioneered the technique of stabilizing lipid bilayers and vesicles by attaching polymerizable reactive groups, particularly diacetylenic groups, to the constituent lipids, and then initiating a polymerization after the supramolecular assembly has formed. The aim of the proposed research is to apply this technique to the stabilization of cubic structures. In particular, the proposed research will design and synthesize polymerizable lipids which are expected to display a bicontinuous cubic phase characterize the polymerized and unpolymerized phases by differential scanning calorimetry, X- ray diffraction and NMR spectroscopy.