Exogenous Co-Reactant-Free Electrochemiluminescent Biosensor for Ratiometric Measurement of α-Glucosidase Based on a ZIF-67-Regulated Hydrogen-Bonded Organic Framework.

The development of highly sensitive and selective analytical approaches for monitoring enzymatic activity is critical for disease diagnosis and biomedical research. Herein, we develop an exogenous co-reactant-free electrochemiluminescence (ECL) biosensor for the ratiometric measurement of α-glucosidase (α-Glu) based on a zeolitic imidazolate framework (ZIF-67)-regulated pyrene-based hydrogen-bonded organic framework (HOF-101). Target α-Glu can hydrolyze maltose to α-d-glucose, which can subsequently react with GO x to produce gluconic acid. The resultant gluconic acid can dissolve ZIF-67, leading to the recovery of the HOF-101 cathodic ECL signal and the decrease of the luminol anodic ECL signal. The long-range ordered structure of HOF-101 can speed up charge transfer, resulting in a stable and strong cathodic ECL signal. Moreover, ZIF-67 can not only efficiently quench the ECL signal of HOF-101 due to ECL resonance energy transfer between HOF-101 and ZIF-67 as well as the steric hindrance effect of ZIF-67 but also enhance the anodic ECL emission of luminol in dissolved O 2 system because of its ordered and porous crystalline structure and the atomically dispersed Co 2+ . Notably, HOF-101 possesses a higher ECL efficiency (32.22%) compared with the Ru(bpy) 3 2+ standard. Importantly, this ratiometric ECL biosensor shows high sensitivity (a detection limit of 0.19 U L -1 ) and a broad linear range (0.2-50 U L -1 ). This biosensor can efficiently eliminate systematic errors and enhance detection reliability without the involvement of exogenous co-reactants, and it displays good assay performance in human serum samples, holding great promise in biomedical research studies.