Constructing bifunctional metal–organic framework based nanozymes with fluorescence and oxidase activity for the dual-channel detection of butyrylcholinesterase

Herein, we reported a novel strategy for the fabrication of bifunctional metal-organic framework based nanozymes (oxidized UiO-66-NH2@Ce), which displayed excellent oxidase mimic activity as well as fluorescence property. The bifunctional oxidized UiO-66-NH2@Ce possess excellent oxidase activity due to oxidase-like active Ce4+/Ce3+ sites, which makes the nanozymes have strong positive charge, resulting in a stronger affinity for the negatively charged chromogenic substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Utilizing the bifunctional oxidized UiO-66-NH2@Ce, a sensitive fluorometric and colorimetric dual-channel detection strategy for butyrylcholinesterase (BChE) was fabricated for the first time. The oxidized UiO-66-NH2@Ce could catalyze the oxidation of colorless ABTS to green oxABTS, which in turn quench the fluorescence of oxidized UiO-66-NH2@Ce. Butyrylcholinesterase (BChE) can catalyze the hydrolysis of S-butyrylthiocholine iodide (BTCh) to produce thiocholine, which could prevent the oxidation of ABTS, resulting in the fluorescence of oxidized UiO-66-NH2@Ce recovered. Both the colorimetric and fluorometric dual-channel sensing platform displayed a sensitive response to BChE, and the limits of detection (LOD) for BChE could achieve as low as 0.056 and 0.050U/L, respectively. The dual-output assay for BChE detection displayed excellent application prospects.