▎ 摘　　要

A facile method for the synthesis of highly fluorescent manganese-doped zinc sulfide (ZnS:Mn) nanocrystals covalently functionalized with polyethylene glycol conjugated graphene oxide (GO-PEG) for drug delivery and cell labeling is reported. First, covalently functionalized GO with PEG-bis(amine) to enhance the solubility and biocompatibility in water and physiological buffers. Second, glutathione (GSH)-coated ZnS:Mn-doped nanocrystals were covalently grafted onto GO-PEG. An acid-amidation process was employed to obtain GO-PEG/ZnS:Mn nanocomposites, which were characterized by UV/Vis, photoluminescence, and Fourier transform infrared spectroscopies, and transmission electron microscopy. Finally, the anticancer drug doxorubicin (DOX) was noncovalently loaded onto these GO-PEG/ZnS:Mn composite particles. High drug entrapment efficiency (100% due to more GO surface available for binding), slow in vitro release of drug (ca. 40% at acidic pH), better HeLa cancer cell killing efficiency (ca. 85%), and cell labeling capability are the important traits of these DOX-loaded nanocomposites. It is believed these novel fluorescent [GO-PEG/ZnS:Mn]-DOX composite particles have great potential as theranostic agents in cancer diagnosis and therapy.