Low-toxicity, water-dispersible perovskite@COF ECL biosensor: Peptide-regulated AgNP quenching for sensitive hCG detection

s Human chorionic gonadotropin (hCG) is a key clinical marker for early pregnancy and trophoblastic disease. We present a turn-on electrochemiluminescence (ECL) biosensor emphasizing materials safety and aqueous compatibility by integrating a CsPbBr₃@COF-LZU1@Au hybrid with a peptide recognition layer. Confining perovskite nanocrystals inside COF-LZU1 yields a porous, mechanically robust shell that suppresses lead ion release, improves water compatibility/dispersion, and mitigates photochemical and hydrolytic degradation, enabling reliable ECL in PBS. A conformal Au nanodomain rim enhances interfacial charge transport and provides mild, covalent (Au S) anchoring sites for the hCG-binding peptide (PPLRINRHILTR-GGGGC), avoiding bulky antibodies and harsh coupling reagents. Signal regulation is achieved with citrate-stabilized Ag nanoparticles that assemble near the peptide in the intact state to quench ECL; specific hCG binding sterically prevents AgNP tethering, restoring emission. Operating under benign aqueous conditions (no organic solvents during measurement, small reagent volumes, room-temperature assembly), the sensor delivers a wide working range (0.05–5000 mIU/mL), a low detection limit (0.047 mIU/mL), high selectivity over common interferents (FSH, LH, TSH, IgG, BSA), excellent reproducibility (RSD ≈ 2.2 %), and strong intraday/long-term/operational stability. Serum tests give ~96–103 % recoveries with low RSDs, indicating minimal matrix effects. By encapsulating lead-based emitters to reduce toxicity risk, enhancing aqueous dispersibility, and using compact peptide ligands for precise molecular recognition, this modular perovskite@COF/Au/peptide design offers a practical and safer route to high-performance ECL diagnostics and can be readily adapted to additional biomarkers by swapping the peptide sequence.