Portable multichannel immunoassay of coxsackievirus A6 using a coordination-engineered iridium-doped ZIF-8 nanozyme

Developing multifunctional nanozymes with well-defined catalytic mechanisms is of considerable interest for analytical sensing applications. Herein, an iridium-doped ZIF-8 nanozyme was developed as a multifunctional signal tag for portable multichannel immunoassay of coxsackievirus A6 (CVA6). The introduction of iridium endowed the material with enhanced peroxidase-like activity and intrinsic photoluminescence, enabling triple-signal readout based on electrochemiluminescence (ECL), colorimetry, and photoluminescence (PL) techniques. Density functional theory calculations revealed that iridium doping improved the adsorption of H₂O₂ by creating more favorable active sites, thereby facilitating electron transfer and promoting the catalytic reaction. Benefiting from these properties, the iridium-doped ZIF-8 nanozyme was employed as a multifunctional label to construct an ECL/colorimetric/PL magnetic immunosensor for CVA6 determination. Under optimized conditions, the proposed platform exhibited a wide linear range from 10⁴ to 10⁹ cps μL^-1. In spiked human serum samples, satisfactory recoveries of 95.85-101.00% for ECL, 97.13-101.15% for colorimetry, and 93.48-111.45% for PL were obtained, with relative standard deviations of 3.85-4.79%, 1.32-2.67%, and 4.42-5.73%, respectively. This work not only provides insight into the coordination-dependent catalytic enhancement of iridium-doped MOF-based nanozymes, but also offers a reliable multichannel immunoassay platform for virus analysis.