Hexagonal Prism-Shaped AIE-Active MOFs as Coreactant-Free Electrochemiluminescence Luminophores Coupled with Hollow Cu2-xO@Pd Heterostructures as Efficient Quenching Probes for Sensitive Biosensing.

For most self-luminous metal-organic framework (MOF)-involved electrochemiluminescence (ECL) systems, the integration of exogenous coreactants is indispensable to promote ECL efficiency. However, the introduction of a coreactant into an electrolyte would result in poor stability, thereby inevitably affecting analytical accuracy. Herein, by employing aggregation-induced emission luminogens as ligands, we first synthesized one hexagonal prism-shaped MOF that displays robust and steady ECL signal without an exogenous coreactant. Furthermore, adenosine triphosphate (ATP), as the target analyte, can be fixed on the electrode surface directly owing to the strong coordination between Zr⁴⁺ and phosphate groups. According to the ECL resonance energy transfer effect, hollow Cu_2-xO@Pd heterostructures are conveniently prepared and act as efficient quenching probes. Remarkably, the resultant urchin-like hollow structure could provide more active sites to anchor ATP aptamers, thus enhancing the ECL quenching efficiency. In this manner, an elaborate coreactant-free ECL system was developed to detect ATP, which demonstrates a remarkable detection limit of 0.17 nM, as well as excellent stability and reproducibility. The present work offers significant enlightenment for the further evolution of advanced ECL systems integrated with MOF-based luminophores.