HIGHER-ORDER SELF-ASSEMBLY OF VESICLES BY SITE-SPECIFIC BINDING

The association of lipid molecules into spherical vesicles in solution as a result of nonspecific intermolecular forces constitutes a primar y self-assembly process. Such vesicles can undergo a secondary self-as sembly into higher order structures in a controlled and reversible man ner by means of site-specific ligand-receptor (biotin-streptavidin) co upling. Cryoelectron microscopy shows these structures to be composed of tethered, rather than adhering, vesicles in their original, unstres sed state. In contrast, vesicles aggregated by nonspecific, such as va n der Waals, forces are deformed and stressed, producing unstable stru ctures. Vesicle association by site-specific binding provides a practi cal mechanism for the production of stable, yet controllable, microstr uctured biomaterials.