▎ 摘　　要

A series of functionalized graphene oxide (GO) with biocompatibility were prepared by grafting polyethylene glycol (PEG) with different molecular weights onto the surface of GO via esterification. Fourier transform infrared (FTIR), Raman spectroscopy and scanning electron microscopy (SEM) were used to investigate structures and morphologies of the as-prepared GO-PEG. Grafting ratios were determined by thermogravimetric analysis (TGA). SEM results indicate that GO-PEG is better exfoliated than GO. GO-PEG displays excellent water dispersity and stability in phosphate buffered saline, and the dispersive stability depends on the grafting ratio. By noncovalent binding interaction, GO-PEG has high loading capacity (as high as similar to 1.75 mg.mg(-1)) for fluorescein (Flu) depending on the grafting ratio. GO-PEG also shows pH-triggered release property for Flu. In addition, by covalent binding between terminal hydroxy groups of the grafted PEG chains and Flu, GO-PEG-Flu fluorescent probes are prepared and cellular imaging of HepG2 cells is realized by the probes.