An electrochemiluminescence immunosensor based on signal magnification of luminol using OER-activated NiFeO@C@CeO/Au as effective co-reaction accelerator.

In this work, a novel, label-free electrochemiluminescence (ECL) immunosensor was constructed for the ultrasensitive detection of carbohydrate antigen 15-3 (CA15-3) by the combined use of NiFeO@C@CeO/Au hexahedral microbox and luminol luminophore. The synthesis of the co-reaction accelerator (NiFeO@C@CeO/Au) was related to the calcination of FeNi-based metal-organic framework (MOF), as well as the ingrowth of CeO nanoparticles and modification of Au nanoparticles. To be specific, the electrical conductivity will be boosted due to the Au nanoparticles, the synergetic effect generated between CeO and calcination FeNi-MOF could offer better activity of oxygen evolution reaction (OER). Herein, the NiFeO@C@CeO/Au hexahedral microbox as a co-reaction accelerator has excellent OER activity and production of reactive oxygen species (ROS), thus increasing the ECL intensity of luminol in a neutral medium without other co-reactants such as HO. Because of these benefits, the constructed ECL immunosensor was applied to detect CA15-3 as an example under optimum conditions, the designed ECL immunosensor exhibited high-level selectivity and sensitivity for CA15-3 biomarker within a linear response range of 0.01-100 U mL and an ultralow detection limit of 0.545 mU mL (S/N = 3), demonstrating its potentially valuable application in the area of clinical analysis.