Interactions Between Unimolecular Micelles and Liposomes

Abstract

AbstractThe interactions between dipalmitoylphosphocholine (DPPC) vesicles and a hyperbranched polymer micelle, Core(hex)PEG5, were examined by visual observation, differential scanning calorimetry (DSC), fluorescence microscopy and dynamic light scattering (DLS). The results from the DSC experiments showed that introducing the polymer to DPPC small unilamellar vesicles completely transformed the vesicles into a large unilamellar structure within minutes, a process that normally takes 2 days at room temperature. The hyperbranched polymers transformed the liposomes to the thermodynamically stable state. Fluorescence microscopy experiments showed that the DPPC vesicles became larger after the polymers were added. In addition, the polymers prevented aggregation of the liposome vesicles yielding clear solutions for up to two weeks at room temperature. In contrast, DPPC vesicles without polymers aggregated to form precipitate within hours at room temperature. The average sizes of liposomes and liposome/polymer were determined by DLS measurement with diameters of 36.3 nm and 65.2 nm, respectively.