Magnetic-Targeted pH-Responsive Drug Delivery System via Layer-by-Layer Self-Assembly of Polyelectrolytes onto Drug-Containing Emulsion Droplets and Its Controlled Release

Novel magnetic-targeted pH-responsive drug delivery system have been designed by the layer-by-layer self-assembly of the polyelectrolytes (oligochitosan as the polycation and sodium alginate as the polyanion) via the electrostatic interaction with the oil-in-water type hybrid emulsion droplets containing the superparamagnetic ferroferric oxide nanoparticles and drug molecules [dipyridamole (DIP)] as cores. Here the drug molecules were directly encapsulated into the interior of droplets without etching the templates and refilling with the desired guest molecules. The drug-delivery system showed high encapsulation efficiency of drugs and drug-loading capacity. The cumulative release ratio of dipyridamole from the oligochitosan/sodium alginate multilayer-encapsulated magnetic hybrid emulsion droplets (DIP/Fe3O4-OA/OA)@(OCS/SAL)(4) was up to almost 100% after 31 h at pH 1.8. However, the cumulative release ratio was only 3.3% at pH 7.4 even after 48 h. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 1969-1976, 2011