Enhanced Peroxidase-like Activity of Fe3O4@MIL-100(Fe) Aroused by ATP for One-Step Colorimetric Sensing toward Cholesterol

Nanozymes have gradually become a research hotspot in the field of enzymology, benefiting from their low cost, high stability, and availability. To break through the limitation that conventional nanozymes exert peroxidase-like (POD-like) activity under only acidic conditions, we rationally designed Fe3O4@MIL-100(Fe) with excellent superparamagnetism and catalytic activity. An optimization of the microwave-assisted in situ synthesis conditions was carried out to obtain the highest POD-like activity of the nanozyme under nearly neutral conditions. Adenosine triphosphate (ATP) was appointed as an auxiliary regulator to further amplify the activity of the nanozyme Fe3O4@MIL-100(Fe). A series of behaviors related to enzymology and the mechanism of ATP-assisted enhancement were further explored. Consequently, a colorimetric sensing strategy was proposed for the one-step detection of cholesterol with a linear range of 0.05–0.4 mM and a limit of detection (LOD) of 1.3 μM (3.3 δ/S). The result of the present work implied that the established one-step platform could be successfully applied to the detection of cholesterol in actual samples. From the nanozyme synthesis to the colorimetric sensing process, the concepts of time savings and straightforwardness were always upheld and satisfactorily implemented. Most importantly, Fe3O4@MIL-100(Fe) could be a great potential biocatalyst candidate for the development of the corresponding commercial kits.