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

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.