A dual-quenching electrochemiluminescence immunosensor based on ABEI@Fe3O4@PDA-PdPt and Cu2-xS nanoflowers for sensitive detection of galectin-3.

Galectin-3 (Gal-3) is a critical biomarker for the diagnosis and prognosis of cardiovascular diseases and tumors, necessitates highly sensitive detection for clinical applications. In this study, a dual-quenching electrochemiluminescence (ECL) immunosensor was developed for the ultrasensitive detection of Gal-3. The sensor employed an N-(4-aminobutyl)-N-ethylisoluminol (ABEI) @Fe3O4@PDA-PdPt composite as an efficient luminophore, where the material's exceptional conductivity and catalytic properties significantly amplified the ECL signal. For signal quenching, secondary antibody-labeled copper-deficient copper sulfide nanoflowers (Ab2-Cu2-xS NFs) were introduced. These nanoflowers enabled a dual-quenching effect through the synergistic mechanisms of resonance energy transfer (RET) and defect-assisted electron dissipation. A sandwich-type ECL immunosensing platform was constructed by sequentially immobilizing the capture antibody, target antigen, and Ab2-Cu2-xS NFs. Under optimized conditions, the proposed immunosensor demonstrated a broad linear detection range for Gal-3 from 1 pg·mL⁻¹ to 500 ng·mL⁻¹, with an exceptionally low detection limit of 24 fg·mL⁻¹. Additionally, the sensor exhibited outstanding specificity, stability, and reproducibility. This work presents a novel strategy for the highly sensitive detection of Gal-3, leveraging the synergistic dual-quenching mechanism to achieve excellent analytical performance, thereby holding significant promise for clinical diagnostics and early disease monitoring applications. The successful construction of this platform also provides a valuable reference for developing advanced ECL systems for other biomarkers.