▎ 摘　　要

In this communication, preparation of graphene quantum dots (GQDs) with size about 10 nm by vigorous oxidation of graphite is reported. Thus obtained GQDs exhibit good physiological solubility, high photostability, low cytotoxicity, and yellow-green fluorescence with quantum yield about 7%. Furthermore, the feasibility of the GQDs for cell imaging application is demosntrated.