(54g) Recombinant Oleosin As a Functional Surfactant

Our laboratory is interested in novel surfactants that can be self-assembled into technologically useful suprastructures and can be equipped with novel biofunctionality. Oleosin is a naturally occurring surfactant protein found in plants. The molecule has three domains â?? two terminal hydrophilic domains, and a central hydrophobic domain with an embedded proline knot, which forces the molecule into a turn. We have obtained the gene for oleosin and expressed it in E.coli, and, using the tools of molecular biology, made hundreds of variants of the molecule, including numerous truncations and additions of functional or targeting domains. Depending on the truncation, oleosin can assemble into vesicles, worm-like micelles, sheets, or spherical micelles â?? assemblies which have utility in drug delivery and tissue engineering. In one application, we show how spherical micelles equipped with receptor targeting domains can be activated by a protease by protecting receptor-targeting domains with protease cleavable domains. The corresponding spherical micelles bind to target cells, but only when both the protease and the receptor are present, effectively creating an â??andâ? switch for cellular recognition. We also show how oleosinâ??s properties as a surfactant can be exploited to stabilize mondisperse air bubbles for ultrasound imaging. We will also provide a further update on ongoing efforts to incorporate other functional domains into oleosin for a variety of applications.