(519c) Formation and Characterization of Bilayer-Decorated Magnetoliposomes

Bilayer-decorated magnetoliposomes have been designed with hydrophobic superparamagnetic iron oxide (SPIOs) nanoparticles using reverse phase evaporation. The ability to embed the nanoparticles (5 nm, oleic acid surface coating) within dipalmitoylphosphatidylcholine (DPPC) bilayers was examined as a function of the lipid to nanoparticle ratio. This ratio varied up to 5000:1, which corresponded to 5000 lipid molecules per nanoparticle. Magnetoliposome structure was observed by cryogenic transmission electron microscopy (cryo-TEM), and the presence of SPIO nanoparticles confirmed by energy dispersive spectroscopy (EDS). Under cryogenic preservation, electromagnetic radiation heated the embedded nanoparticles and holes were burnt within the lipid bilayers, further verifying decoration. Lipid phase behavior was examined by differential scanning microcalorimetry (Nano DSC) and showed that the nanoparticles eliminated the gel to rippled gel pretransition and increased and broadened the rippled gel to fluid melting temperature. Carboxyfluorescein leakage experiments were used to demonstrate the ability to control magnetoliposome bilayer permeability using external radio frequency (RF) inductive heating. Our results show that SPIO nanoparticles can be bound to lipid bilayers and externally heated to induce and control leakage of encapsulated agents by adjusting the lipid to nanoparticle ratio. Results will also be presented on the design of cationic magnetoliposomes selectively decorated with anionic SPIO nanoparticles bound at the lipid headgroup/water interface.