Cisplatin-loaded polymer/magnetite composite nanoparticles as multifunctional therapeutic nanomedicine

Multifunctional nanocarriers with multilayer core-shell architecture were prepared by coating superparamagnetic Fe₃O₄ nanoparticles with diblock copolymer folate-poly(ethylene glycol)-b-poly(glycerol monomethacrylate) (FA-PEG-b-PGMA), and triblock copolymer methoxy poly(ethylene glycol)-b-poly(2-(dimethylamino) ethyl methacrylate)-b-poly(glycerol monomethacrylate) (MPEG-b-PDMA-b-PGMA). The PGMA segment was attached to the surfaces of Fe₃O₄ nanoparticles, and the outer PEG shell imparted biocompatibility. In addition, folate was conjugated onto the surfaces of the nanocarriers. Cisplatin was then loaded into the nanocarrier by coordination between the Pt atom in cisplatin and the amine groups in the inner shell of the multilayer architecture. The loaded cisplatin showed pH-responsive release: slower release at pH 7.4 (i.e. mimicking the blood environment) and faster release at more acidic pH (i.e. mimicking endosome/lysosome conditions). All of the cisplatin-loaded nanoparticles showed concentration-dependent cytotoxicity in HeLa cells. However, the folate-conjugated cisplatin-loaded carriers exhibited higher cytotoxicity in HeLa cells than non-folate conjugated cisplatin-loaded carriers.