Confined ZrO2 possessing triple catalytic functionality boosts luminol-dissolved oxygen electrochemiluminescence for immunoassay.

Developing high-performance electrochemiluminescence (ECL) is of great importance for trace cytokine analysis. Herein, zirconium dioxide (ZrO2) encapsulated within the silica nanochannel films (SNF) were first employed to amplify the ECL response of the luminol-dissolved oxygen (DO) system. ZrO2 nanoparticles were in-situ synthesized and confined within the SNF channels via a one-step electrodeposition strategy. Benefiting from its unique triple catalytic functionality, SNF-confined ZrO2 acts as an efficient co-reactant accelerator, resulting in markedly enhanced ECL performance. During the initial cathodic scan, the confined ZrO2 promotes the oxygen reduction reaction (ORR), generating superoxide anion radicals (O2•-) and H2O2. In the subsequent anodic scan, the confined ZrO2 not only catalyzes the conversion of in-situ generated H2O2 into O2•-, but also facilitates the conversion of luminol anion (LH-) to its radical anion (L•-). These synergistic processes ensure efficient generation of abundant O2•- and L•-, ultimately boosting the ECL emission. Furthermore, an ECL immunosensor was fabricated for interleukin-6 (IL-6) detection through the oriented immobilization of antibodies on the external surface of SNF. The constructed immunosensor displays a wide linear range (1 fg mL-1 to 10 ng mL-1) and a low detection limit of 0.24 fg mL-1. This work demonstrates that SNF-confined ZrO2 holds promise as a versatile co-reactant accelerator for the construction of highly efficient ECL systems.