▎ 摘　　要

A sensitive and selective graphene oxide (GO)-based fluorescent nanoprobe has been developed for the relay recognition of Cu2+ and cysteine (Cys) by covalently grafting -aminobutyric acid (GABA) onto GO. The fluorescence of the probe (with excitation/emission maxima at 360/445nm) is selectively quenched by Cu2+ via static fluorescence quenching. Fluorescence drops linearly as the concentration of Cu2+ is increased from 50nM to 1.0 mu M, and the detection limit for Cu2+ is calculated as 15nM. By virtue of the strong interaction between Cys andCu(2+), the GO-GABA/Cu2+ complex can further sensitively recognize Cys in a switch-on mode. The linear range for Cys detection is from 50nM to 1.0 mu M, and the detection limit is 38nM. The probe has low cytotoxicity, and it works well inside living cells, which is verified by the successful application in imaging of LLC-PK1 cells.