Sensitive Pb2+ Probe Based on the Fluorescence Quenching by Graphene Oxide and Enhancement of the Leaching of Gold Nanoparticles

A novel strategy was developed for fluorescent detection of Pb2+ in aqueous solution based on the fact that graphene oxide (GO) could quench the fluorescence of amino pyrene (AP)-grafted gold nanoparticles (AP–AuNPs) and Pb2+ could accelerate the leaching rate of AuNPs in the presence of S2O32–. In this system, fluorescence reporter AP was grafted on AuNPs through the Au–N bond. In the presence of GO, the system shows fluorescence quenching because of π–π stacking between AP and GO. With the addition of Pb2+ and S2O32–, the system displays fluorescence recovery, which is attributed to the fact that Pb2+ could accelerate the leaching of the AuNPs from GO surfaces and release of AP into aqueous solution. Interestingly, the concentration of GO could control the fluorescence "turn-off" or "turn-on" for Pb2+ detection. In addition, GO is also an excellent promoter for the acceleration of the leaching of AuNPs and shortening the analytical time to ∼15 min. Under the optimal conditions, the fluorescence Pb2+ sensor shows a linear range from 2.0 × 10–9 to 2.3 × 10–7 mol/L, with a detection limit of 1.0 × 10–10 mol/L.