▎ 摘　　要

A novel electrochemiluminescence (ECL) signal-off strategy based on CuS in situ grown on reduced graphene oxide (CuS-rGO) quenching luminol/H2O2 system was firstly proposed. Luminol was grafted on the surface of Au@Fe3O4-Cu-3(PO4)(2) nanoflowers (Luminol-Au@Fe3O4-Cu-3(PO4)(2)) which exhibited excellent catalytic effect towards the reduction of H2O2 to enhance the ECL intensity of luminol. Cu-3(PO4)(2) nanoflowers showed large surface area which can immobilize more Fe3O4 and Au nanoparticles. The quenching mechanism of CuS-rGO was due to ECL resonance energy transfer (RET). The spectral overlap between fluorescence spectrum of Luminol-Au@Fe2O4-Cu-3(PO4)(2) and UV-vis absorption spectrum of CuS-rGO revealed that resonance energy transfer was possible. Au nanoparticles were immobilized on the surface of CuS-rGO to capture secondary antibodies. After a sandwich-type immunoreaction, a remarkable decrease of ECL signal was observed. Under the optimal conditions, the immunosensor showed excellent performance for N-terminal pro-brain natriuretic peptide (NT-proBNP) detection with a wide detection range from 0.5 pg mL(-1) to 20 ng mL(-1) and a low detection limit of 0.12 pg(-1) (S/N = 3). The prepared NT-proBNP immunosensor displayed high sensitivity, excellent stability and good specificity.