Interface-regulated MOF/g-C3N4 heterostructure for electrode passivation elimination: Ultrasensitive electrochemiluminescence sensing of CA15–3 via ECL-RET

초록

The development of stable and efficient luminophores remains a critical challenge in electrochemiluminescence (ECL) sensing. Graphitic carbon nitride (g-C<inf>3</inf>N<inf>4</inf>) has emerged as a promising luminophore due to its high stability and low toxicity, yet its practical application is constrained by limited surface area, poor conductivity, and severe electrode passivation. Herein, a metal-organic framework (MOF)/g-C<inf>3</inf>N<inf>4</inf> (NH<inf>2</inf>-UiO-66/g-C<inf>3</inf>N<inf>4</inf>, NUCN) heterostructure luminophore was constructed via interface engineering. The integration of NH<inf>2</inf>-UiO-66 (NU) remarkably enhanced electrical conductivity, surface area and ECL efficiency of g-C<inf>3</inf>N<inf>4</inf>. Mechanistically, the low LUMO level of NU enabled efficient electron capture from the conduction band of g-C<inf>3</inf>N<inf>4</inf>, which eradicated electrode passivation and directly contributed to the 4.6 % enhancement in ECL efficiency. Concurrently, the NUCN heterostructure featured increased Brunauer-Emmett-Teller (BET) surface area and abundant amino groups, collectively enhancing its antibody loading capacity for biomolecular recognition. This dual improvement—electron transfer optimization for ECL performance and structural modification for biomolecule immobilization—collectively enabled the ultrasensitive sensing capability of the NUCN-based platform. In addition, the absorption spectrum of PANI-sCuO quencher exhibited strong overlap with the ECL emission of NUCN at 452 nm, enabling ECL resonance energy transfer (ECL-RET)-mediated signal quenching. This allowed target-induced quenching to generate pronounced ECL intensity variation, thereby achieving ultrasensitive detection via signal amplification. Leveraging the NUCN/PANI-sCuO system, a sandwich-type immunosensor was developed for carbohydrate antigen 15–3 (CA15-3), featuring a linear range of 0.05–600 U/mL and a detection limit of 0.02 U/mL, demonstrating its potential for clinical biomarker analysis. © 2025 Elsevier B.V., All rights reserved.

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