Magnetic Fe₃O₄-graphene composites as targeted drug nanocarriers for pH-activated release

A novel nanocarrier of magnetic Fe₃O₄-graphene nanocomposites (MGNs) was proposed as an effective drug delivery system for cancer treatment. The nanocarrier was synthesized by covalently attaching modified Fe₃O₄ nanoparticles onto water-soluble graphene sheets via the formation of an amide bond with the aid of 1-ethyl-3-(3- dimethyaminopropyl) carbodiimide. The obtained MGNs exhibited excellent dispersibility and stability in aqueous solution and they also exhibited superparamagnetic properties with a saturation magnetization of 23.096 emu g^-1. An efficient loading of 5-fluorouracil (5-FU) on MGNs as high as 0.35 mg mg^-1 was obtained. Furthermore, the in vitro drug release of 5-FU was examined in pH 6.9 and pH 4.0 buffers at 37°C, and showed strong pH dependence. Transmission electron microscope observations revealed that MGNs can be internalized efficiently by HepG2 cells. More importantly, the cytotoxicity evaluation shows that the resulting MGNs exhibit excellent biocompatibility. The as-prepared nanocarrier system combined the advantages of the superparamagnetic iron oxide nanoparticles and water-soluble graphene sheets, which will find many potential applications in biomedicine and biomaterials.