▎ 摘　　要

By employing two-dimensional and water-soluble graphene oxide (GO), a turn-on sensor was developed for the label-free detection of Zn2+ based on Zn2+-induced G-quadruplex (G4) formation. Indicated using the G4-binding ligand thiazole orange (TO), the enhanced fluorescent signal could be generated only when the guanine-rich DNA was excluded from the surface of GO due to the formation of a G4 induced by Zn2+. The results have shown that the method can be utilized for the detection of Zn2+ in a linear range from 0-30 mu M with a detection limit of 0.71 mu M. The real sample testing conducted in serum samples demonstrated its practical potential in biological analysis.