Functionalized graphene oxide/Fe₃O₄ hybrids for cellular magnetic resonance imaging and fluorescence labeling

In this work, we developed a T₂-weighted contrast agent based on graphene oxide (GO)/Fe₃O₄ hybrids for efficient cellular magnetic resonance imaging (MRI). The GO/Fe₃O₄ hybrids were obtained by combining with co-precipitation method and pyrolysis method. The structural, surface and magnetic characteristics of the hybrids were systematically characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), AFM, Raman, FT-IR and XRD. The GO/Fe₃O₄ hybrids were functionalized by modifying with anionic and cationic polyelectrolyte through layer-by-layer assembling. The fluorescence probe fluorescein isothiocyanate (FITC) was further loaded on the surface of functionalized GO/Fe₃O₄ hybrids to trace the location of GO/Fe₃O₄ hybrids in cells. Functionalized GO/Fe₃O₄ hybrids possess good hydrophilicity, less cytotoxicity, high MRI enhancement with the relaxivity (r₂) of 493 mM^− 1 s^− 1 as well as cellular MRI contrast effect. These obtained results indicated that the functionalized GO/Fe₃O₄ hybrids could have great potential to be utilized as cellular MRI contrast agents for tumor early diagnosis and monitoring.