Silica-detoxified perovskite ECL: Cas13a-triggered signal-on sensing with CsPbBr₃@SiO₂@Au

Perovskite nanocrystals are attractive ECL emitters but suffer from poor water stability and potential toxicity. Here we report a signal-on electrochemiluminescent biosensor that integrates CsPbBr₃@SiO₂@Au nanocomposites with a CRISPR/Cas13a-Nb.BbvCI amplification cascade for ultrasensitive microRNA detection. The CsPbBr₃ core provides bright emission, a conformal SiO₂ shell enhances water compatibility and suppresses ion leakage, and surface Au nanoparticles offer abundant sites for thiolated ferrocene-hairpin (Fc-HP) immobilization. In the resting state, proximal Fc efficiently quenches the CsPbBr₃ ECL. Target miRNA activates Cas13a to cleave a dumbbell probe and release an intermediate strand that hybridizes with Fc-HP; subsequent Nb.BbvCI nicking removes Fc from the electrode and is recycled, producing robust signal restoration. Morphology (TEM), composition (EDS/XPS), and stepwise electrochemistry (CV/EIS) verify a core-shell-Au architecture and a reliably assembled interface that follows the expected quench→restore behavior. Under optimized conditions (0.5 mg mL^-1 CsPbBr₃@SiO₂@Au, 2.0 μM Fc-HP, 40 min target incubation, 100 mM TPrA, 120 s pre-reaction), the assay affords a 1 aM-1.0 × 10⁹ aM linear range with an estimated limit of detection (LOD) of 1.86 aM. The sensor shows high specificity against homologous sequences and achieves 95.22%-104.61% recoveries with RSD < 5% in spiked serum. Pilot measurements distinguish patient serum samples from healthy controls, underscoring clinical potential. This modular platform couples stable perovskite ECL emission with programmable CRISPR chemistry, offering a sensitive, selective, and water-compatible route for microRNA analysis and readily extensible nucleic-acid diagnostics.