Quantification of Zn(ii) using a label-free sensor based on graphene oxide and G-quadruplex

Abstract

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 μM with a detection limit of 0.71 μM. The real sample testing conducted in serum samples demonstrated its practical potential in biological analysis.