Ultrasensitive detection of lead ion sensor based on gold nanodendrites modified electrode and electrochemiluminescent quenching of quantum dots by electrocatalytic silver/zinc oxide coupled structures.

A signal-off electrochemiluminescence (ECL) DNA sensor based on gold nanodendrites (Au NDs) modified indium tin oxide (ITO) electrode for the detection of lead ion (Pb2+) was developed. Well-defined Au NDs were prepared on ITO electrode using low-potential synthesis, assisted by ethylenediamine. Based on Pb2+-specific deoxyribozyme, the silver/zinc oxide (Ag/ZnO) with coupled structure, prepared by one-pot method, was close to the surface of the electrode to catalyze the reduction of part of H2O2, the coreactant for cathodic ECL emission, leading to a decrease of ECL intensity. In addition, taking advantage of the larger surface area to capture a large amount of capture probe as well as excellent conductivity of Au NDs, the sensor could detect Pb2+ quantitatively in a wider range, and performed excellent selectivity. Furthermore, such simple and sensitive DNA sensor was successfully applied for the detection of Pb2+ in lake water and human serum samples, respectively.