Multiple signal amplification electrochemiluminescent immunoassay for Sudan I using gold nanorods functionalized graphene oxide and palladium/aurum core-shell nanocrystallines as labels

Herein, a novel ultrasensitive competition-type electrochemiluminescent (ECL) immunosensor for detecting Sudan I was constructed using palladium/aurum core-shell nanocrystallines (Pd/Au CSNs) and CdSe@CdS QDs as signal bioprobe. The Pd/Au CSNs as outstanding nanocarrier equipped with superior performance like highly catalytic activity, good biocompatibility and large specific surface area, which enhanced ECL intensity significantly. The surface of electrode was coated with gold nanorods functionalized graphene oxide (GNRs/GO) nanocomposite film as the substrate, which provided an effective matrix to immobilize more coating antigen but also facilitated the electronic transmission to increase the ECL signal. The proposed immunoassay based on the synergistic effect of Pd/Au CSNs and GNRs/GO for determining Sudan I exhibited good stability, high sensitivity and wide linearity with a lower detection limit of 0.3 pg mL−1 (S/N = 3) and the wide range from 0.001 to 500 ng mL−1. Furthermore, the developed immunosensor was successfully applied in determination of real samples with acceptable accuracy, and initiated a new route for detecting other small molecule in the future.