Synergistic enhancement of luminol-dissolved oxygen electrochemiluminescence by CeO2 nanozymes and mildly oxidized porous silicon heterostructure for ultrasensitive alpha-fetoprotein immunoassay

Developing highly sensitive electrochemiluminescence (ECL) systems is crucial for the analysis of tumor biomarkers. Herein, mildly oxidized porous silicon (MOPSi) was firstly employed to immobilize cerium oxide (CeO 2 ) nanozymes to amplify the ECL response of the luminol-dissolved oxygen (DO) system in a near-neutral condition for Alpha-fetoprotein (AFP) immunoassay. MOPSi nanoparticles possess a unique Si core/SiOₓ shell structure that enables the stable anchoring and dispersion of CeO 2 via Ce-O-Si bonds. Notably, CeO 2 -MOPSi/ITO exhibits a markedly higher ECL intensity than CeO 2 /ITO and MOPSi/ITO owing to the robust heterostructure formed between CeO 2 and MOPSi. The CeO 2 -MOPSi heterointerface enables a self-cascade catalytic process that comprises efficient oxygen reduction to produce superoxide anion radicals (O 2 •- ) and H 2 O 2 , followed by the in-situ conversion of the generated H 2 O 2 into additional O 2 •- . The abundant O 2 •- reacts with luminol radical anion (L •- ), leading to an enhanced ECL response. Moreover, an AFP immunosensor was fabricated by anchoring antibodies onto MOPSi surface. The proposed sensor shows a broad linear range from 10 fg/mL to 10 ng/mL with a detection limit of 3.3 fg/mL. This work provides a novel strategy for integrating the MOPSi carrier with nanozymes to develop advanced ECL systems for high-performance bioanalysis. Download: Download high-res image (123KB) Download: Download full-size image