Surface passivation suppression in Zn-MOF for enhanced ECL sensing

Zinc-based metal-organic framework (Zn-MOF), has been demonstrated to be a promising electrochemiluminescence (ECL) luminophore, owing to its tunable structures and functional versatility. It exhibited voltage-dependent ECL enhancement, however, repeated high-potential cycling induced progressive signal instability due to conductive band electron accumulation, which reduced electron-hole recombination efficiency and accelerated electrode passivation. Herein, SnS₂ QDs (quantum dots) decorated Zn-MOF (SnS₂ QDs@Zn-MOF) was synthesized and employed as the efficient luminophore. SnS₂ QDs, serving as electron acceptors, effectively trap over-injected electrons to prevent electrode passivation. Upon target binding, the ECL signal was quenched by dopaminequinone (DQ), which is the electro-oxidation product of dopamine. The resulting biosensor exhibited a broad linear range from 0.1 nM to 100 μM and an ultralow detection limit of 0.072 nM. Overall, this work provides a promising strategy for the development of high-performance ECL biosensors.