Metal−organic frameworks (MOFs) with uniform porosity and large surface areas can function as carriers of immobilized enzymes. However, drawbacks including long response times or enzyme leakage have hindered their applicability. In this study, a boronic acid-functionalized hierarchically porous MIL-88B (HP-MIL-88B-BA) was prepared as an efficient immobilization matrix for glucose oxidase (GOx). HP-MIL-88B-BA features a hierarchical, porous structure with sufficient recognition sites that facilitate GOx immobilization and prevent enzyme leakage. This hierarchical porosity increased the substrate mass transfer efficiency, thereby reducing the response time. Moreover, HP-MIL-88B-BA can be used as a horseradish peroxidase mimic. In this manner, an integrated nanozyme was constructed for the rapid one-step detection of glucose. GOx@HP-MIL-88B-BA exhibited a rapid response to glucose (10 min) and displayed a good linear relationship from 2 to 100 μM with a detection limit of 0.98 μM. This novel methodology provides a straightforward, rapid, and efficient strategy for integrated nanozyme synthesis for biosensing purposes.

The impurity of salicylic acid (SA) in aspirin is a required inspection item for drug quality control. Since free SA is significantly toxic for humans, the content determination of free SA is absolutely necessary to ensure people's health. In this work, a facile colorimetric method was developed for the detection of SA in aspirin by utilizing the MIL-53(Fe) nanozyme. As MIL-53(Fe) possesses enzyme mimicking catalytic activity, 3,3,5,5-tetramethylbenzidine (TMB) can be easily oxidized to blue-oxidized TMB (oxTMB) with the existence of H 2 O 2. Moreover, an inhibition effect on the catalytic activity of the MIL-53(Fe) nanozyme is induced due to the specific complexation between SA and Fe 3+ in the center of MIL-53(Fe), which results in a lighter color in the oxTMB. The color change of oxTMB can be seen easily by the naked eye with the addition of different concentrations of SA. Thus, a simple colorimetric platform was established for effectively monitoring SA. A good linear relationship (R 2 = 0.9990) was obtained in the concentration range of 0.4-28 µmol L −1 , and the detection limit was 0.26 µmol L −1. In particular, the rationally designed system has been well-applied to the detection of SA impurity in aspirin. Satisfyingly, the detection results are highly in accord with those of HPLC. This novel colorimetric platform broadens the application prospects of nanozymes in the field of pharmaceutical analysis.