Choline Oxidase-Integrated Copper Metal–Organic Frameworks as Cascade Nanozymes for One-Step Colorimetric Choline Detection
2022
Huang, Hui | Song, Donghui | Zhang, Wenjing | Fang, Shuaizhen | Zhou, Qianxi | Zhang, Haoyu | Liang, Zheng | Li, Yongxin
Choline is an important factor for regulating human health and is widely present in various foods. In this work, a sensor strategy based on a choline oxidase-integrated copper(II) metal–organic framework with peroxidase-like activity is constructed for one-step cascade detection of choline. The one-step cascade strategy can avoid intermediate product transferring in general multi-step reactions, and the multi-enzyme activities can be well exerted under one condition, thus exhibiting excellent catalytic activity and enhanced stability. In the integrated system, choline is catalyzed by ChOₓ to produce betaine and H₂O₂, which eventually got converted to hydroxyl radicals by the peroxidase nanozyme, oxidized the chromogenic substrate ABTS, and produced an observable absorption peak at 420 nm. A new choline detection method was thus established and showed a satisfactory linear relationship at 6–300 μM, which has been used for the choline analysis in milk.
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