Co-amplification of luminol-based electrochemiluminescence immunosensors based on multiple enzyme catalysis of bimetallic oxides CoCeOx and NiMnO3 for the detection of CYFRA21-1

Abstract

The accelerated energy supply of co-reactants is an extremely effective strategy for achieving highly sensitive electrochemiluminescence analysis, and binary metal oxides would be an excellent tool for this purpose owing to the nano-enzyme acceleration of mixed metal valence states. Herein, an electrochemiluminescent (ECL) immunosensor for monitoring the concentration of cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) was developed based on a co-amplification strategy triggered by two bimetallic oxides, CoCeO_x and NiMnO₃, with luminol as the luminophore. CoCeO_x derived from an MOF exhibits a large specific surface area and excellent loading capacity as a sensing substrate, and the peroxidase properties enable the catalysis of hydrogen peroxide to provide energy supply to the underlying radicals. The dual enzymatic properties of flower-like NiMnO₃ were employed as probe carriers for luminol enrichment. The peroxidase properties built on Ni²⁺/Ni³⁺ and Mn³⁺/Mn⁴⁺ binary redox pairs resulted in the integration of highly oxidative hydroxyl radicals, and the oxidase properties provided additional superoxide radicals via dissolved oxygen. The practically proven multi-enzyme-catalyzed sandwich-type ECL sensor easily accomplished an accurate immunoassay of CYFRA21-1, harvesting a detection limit of 0.3 pg mL⁻¹ in the linear range of 0.001–150 ng mL⁻¹. In conclusion, this work explores the cyclic catalytic amplification of mixed-valence binary metal oxides with nano-enzyme activity in the field of ECL and develops an effective pathway for ECL immunoassay.