A novel collapse strategy of zeolitic imidazole frameworks shell triggered by p-benzoquinone for the fluorescence monitoring α-glucosidase activity and screening natural anti-diabetes drug

Luminescent materials encapsulated into zeolite imidazole framework-8 (ZIF-8) as fluorescent probes are widely applied to detect the various analytes. Notably, these analytes react with Zn2+ through the coordination, oxidation, or acidification of 2-methylimidazole (2-MIM) to cause the degradation of ZIF-8 shell, which enormously constraints the improvement of the sensor sensitivity and selectivity. Herein, we have rationally designed the new way to collapse the shell of ZIF-8 entrapped with copper nanoclusters (CuNCs@ZIF-8) triggered by p-benzoquinone. It is worth noting that p-benzoquinone reactions with 2-MIM through hydrogen bonding interaction. As a proof-of-concept, a sensitive method for the detection of hydroquinone (HQ) is developed based on the degradation of CuNCs@ZIF-8 because HQ is easily oxidized to p-benzoquinone. The limit of detection (LOD) is estimated as low as 76 nM. Importantly, this method is highly selective for HQ over other dihydroxybenzene isomers. Inspired by the generation of HQ from hydrolysis of α-arbutin as a substrate for α-glucosidase (α-Glu), we have further proposed a straightforward α-Glu activity assay. LOD is down to 0.003 U/mL, which is lower than most of other α-Glu activity assays. Moreover, the inhibition effect of acarbose and three kinds of natural flavonoids including baicalein, silibinin, and apigenin on α-Glu activity is measured with IC50 values of 37, 155, 1940, and 2930 nM, respectively. The synergistic and antagonistic inhibition effect of α-Glu activity is also evaluated by binary combination with three types of flavonoids. This approach provides a promising strategy in clinical diagnosis and anti-diabetic drug screening.