A novel disposable immunosensor based on quenching of electrochemiluminescence emission of Ru(bpy)32+ by amorphous carbon nanoparticles

Novel amorphous carbon nanoparticles (ACNPs) with high electrochemiluminescence (ECL) quenching efficiency were prepared from candle soot with a quite simple approach. The prepared ACNPs were employed as novel energy quenchers for an ECL immunosensor on a disposable screen-printed carbon electrode array (SPCEA) substrate. Gold nanoparticles-doped chitosan composite film was utilized to immobilize Ru(bpy) 3 2+ -labeled antibody on the SPCEA, and ACNPs were linked with antigens to obtain ACNP-antigen conjugate. The immunoreaction between the Ru(bpy) 3 2+ -labeled antibody and the ACNP-antigen conjugate bridged the Ru(bpy) 3 2+ donor and the ACNPs acceptor, which led to quenching of ECL emission from Ru(bpy) 3 2+ via energy transfer. In the presence of the target antigen, this antigen competed with the ACNP-antigen for the immobilized Ru(bpy) 3 2+ -labeled antibody, thus led to decreased occurrence of the ECL quenching. This ACNPs-based ECL quenching system was successfully applied to detect mouse IgG, which was used as a model analyte. The method showed a linear range of 0.50–400   ng   mL −1 and a detection limit of 0.35   ng   mL −1 . The results for real sample assay and recovery test demonstrated the reliability of this ECL quenching-based immunosensor. It could be further extended to multiplexed immunoassay of biomarker proteins for clinical diagnosis.