Mechanistic insights into persulfate-driven electrochemiluminescence amplification enabled by a Ru@Cu-MOGs/Zr-CeO2-Ag hybrid system.

Electrochemiluminescence (ECL) is well suited for ultrasensitive bioanalysis; however, persulfate-based ECL systems often suffer from inefficient electron transfer and unstable reactive intermediates, which restrict signal amplification. Herein, a signal-enhanced ECL immunosensing platform was developed by integrating Ru(bpy)32+-loaded copper-based metal-organic gels (Ru@Cu-MOGs) with a functionalized persulfate coreaction accelerator for alpha-fetoprotein (AFP) detection. Ru@Cu-MOGs synthesized via a one-pot strategy enable stable luminophore immobilization and reliable ECL emission. To promote persulfate activation, silver nanoparticles supported on a Zr/CeO2 heterojunction (AZC) were introduced. The synergistic effects of enhanced interfacial conductivity, stabilized Ce3+/Ce4+ redox cycling, and increased oxygen-vacancy density facilitate efficient sulfate radical generation, resulting in pronounced ECL signal enhancement. Under optimized conditions, the proposed immunosensor exhibits a linear response to AFP from 1 pg mL-1 to 200 ng mL-1 with a detection limit of 706.4 fg mL-1, along with good reproducibility, stability, and selectivity in spiked human serum samples. This work provides a rational strategy for improving persulfate-driven ECL systems for sensitive bioanalysis.