Au@NiMnO₃@g-C₃N₄-based electrochemiluminescence immunosensor for sensitive procalcitonin assay via quenching by...

Herein, Au@NiMnO₃@g-C₃N₄ nanocomposites were synthesized and subsequently employed as coreaction accelerators for the luminol/H₂O₂ electrochemiluminescence (ECL) system. The Au@NiMnO₃@g-C₃N₄ nanocomposites exhibited excellent peroxidase-like and oxidase-like catalytic activities, efficiently catalyzing the decomposition of H₂O₂ to generate reactive oxygen species (ROS) and markedly enhancing the ECL emission of the luminol/H₂O₂ system. Mechanistic investigations revealed that the ECL intensity was directly dependent on the catalytic activity of the nanocomposite promoter. In addition, tungsten-based polyoxometalate nanoclusters (W-POM NCs) with remarkable ROS-scavenging activity were employed as quenchers and secondary antibody labels, thereby improving the sensitivity of the biosensor. Finally, a sandwich-based ECL immunosensor combining the enhancement effect of Au@NiMnO₃@g-C₃N₄ with the quenching capability of W-POM NCs was developed for the ultrasensitive quantification of procalcitonin (PCN). Under the optimized conditions, the immunosensor enabled the sensitive immunoassay of PCN, achieving a detection limit of 8.91 × 10^-5 ng mL^-1 over a linear range of 0.0001-100 ng mL^-1. Hence, this biosensor provides an efficient strategy for the clinical diagnosis and early screening of PCN.