▎ 摘　　要

Assembly of Fe3O4 nanoparticles (NPs) on PEG-functionalized graphene oxide for efficient magnetic imaging and drug delivery are reported. Nanoscale graphene oxide (GO) was first synthesized and functionalized by branched, biocompatible polyethylene glycol (PEG) to render high aqueous solubility and stability in physiological solutions. Next, the meso-2,3-dimercaptosuccinnic acid-modified Fe3O4 NPs were anchored onto GO sheets via formation of an amide bond in the presence of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC). It was found that the Fe3O4-PEG-GO nanocomposites possess good physiological stability and low cytotoxicity. Furthermore, controlled loading of aromatic drugs, doxorubicin (DOX), a typical anticancer drug, onto the Fe3O4-PEG-GO nanocomposites via pi-pi stacking and hydrophobic interactions is investigated. It is demonstrated that Fe3O4-PEG-GO/DOX loaded with the anticancer drug shows remarkably high cytotoxicity. The Fe3O4-PEG-GO/DOX nanocomposites show significantly enhanced cellular MRI, being capable of detecting cells at the iron concentration of 10 mg mL(-1) with cell density of 2 x 10(5) cells per mL. The current work provides a general approach toward rational design and synthesis of a versatile theranostic nanoplatform based on Fe3O4-PEG-GO NPs with good biocompatibility and the capability of simultaneously performing imaging and therapy for clinical outcomes.