A novel electrochemiluminescence (ECL) signal amplified strategy based on self-catalyzed luminol derivative and carbon nanohorn-based hybrid for luminol/H2O2 system was firstly proposed, and applied to fabricate an ultrasensitive ECL immunosensor for the detection of N-terminal pro-brain natriuretic peptides (NT-proBNP). Initially, PdCu nanocubes supported single-walled carbon nanohorn (PdCu@SWCNHs) hybrid was successfully synthesized through a facile one-pot strategy. For signal tag fabrication, 3,4,9,10-perylenetetracarboxylic acid (PTCA) conjugated luminol (PTC-Lu) as a novel self-catalyzed luminescence emitter was prepared and then effectively immobilized on the PdCu@SWCNHs to form PTC-Lu/PdCu@SWCNHs nanocomposite via pi-pi stacking. Herein, PTCA was selected and introduced into the luminol/H2O2 ECL system for the first time, which could not only increase the luminescence signal but also remarkably improve the stability and hydrophilicity of pristine SWCNHs. More notably, PdCu@SWCNHs nanohybrid showed superior catalytic activity toward H2O2 that could further amplify the ECL signal of luminol/H2O2 system. Meanwhile, good biocompatibility and high specific surface area of PdCu nanocubes make the composite possess excellent property for immobilization of detection antibody. Based upon above, the proposed "signal on" immunosensor exhibited a wide linear detection range of 0.1 pg ml(-1) to 25 ng mL(-1) with a relatively low detection limit of 0.05 pg mL(-1), and successfully achieved the detection in clinical human serum samples with desirable results.
