Development of CA-125 electrochemiluminescence immunosensing platform based on using NiCo2O4 as the oxygen evolution reaction catalyst and Cu@WO3 as quencher

Conventional luminol co-reactant electrochemiluminescence (ECL) systems are limited by the instability of hydrogen peroxide and insufficient reactive oxygen species (ROS) generation from dissolved oxygen. Herein, nickel‑cobalt bimetallic oxide (NiCo 2 O 4 ) was synthesized via a hydrothermal method and used as an oxygen evolution reaction (OER) electrocatalyst to construct an efficient luminol/H 2 O ECL system. NiCo 2 O 4 promoted water oxidation to generate ROS in situ, thereby enhancing the luminol ECL emission. Among the samples obtained at different calcination temperatures, the catalyst calcined at 450 °C (NiCo 2 O 4 –450) exhibited the superior OER activity, with an overpotential of 401 mV at 10 mA/cm 2 and a Tafel slope of 42.21 mV/dec in 1.0 M KOH. Furthermore, Cu-doped WO 3 (Cu@WO 3 ) nanocomposites were employed as resonance energy transfer (RET) acceptors to quench luminol emission. On this basis, a quench-typed ECL immunosensing system was developed. The fabricated immunosensor showed sensitive response to ovarian cancer biomarker CA-125 concentration from 0.001 U/mL to 50 U/mL with detection limit of 3.16 × 10 −5 U/mL (S/N = 3). This study offers a promising luminol/H 2 O ECL strategy for sensitive bioassay applications.