▎ 摘　　要

A novel gene delivery system based on graphene oxide chemicallyfunctionalized with branched polyethylenimine (PEI-GO) is reported. The PEI-GO conjugate was formed by the covalent linking of PEI and GO via an amide bond by widely used EDC chemistry. Thus prepared PEI-GO exhibits an excellent ability to condense DNA at a low mass ratio with a positive potential of 49 mV. A WST assay reveals that PEI-GO is significantly less cytotoxic than PEI 25 kDa. Finally, the transfection efficiency of PEI-GO was evaluated. It is demonstrated that the luciferase expression of PEIGO is comparable or even higher than that of the PEI 25 kDa at optimal mass ratio. Moreover, intracellular tracking of Cy3-labelled pGL-3 indicates that PEI-GO could effectively deliver plasmid DNA into cells and be localized in the nucleus. These findings suggest that PEI-GO is a promising candidate for efficient gene delivery.