Glutamate Oxidase-Integrated Biomimetic Metal–Organic Framework Hybrids as Cascade Nanozymes for Ultrasensitive Glutamate Detection
Hongtong Hu, Peikun Li, Zichen Wang, Yingjie Du, Geling Kuang, Yuxiao Feng, Shiru Jia, Jiandong Cui
Abstract
The hybrid coupling of biocatalysts and chemical catalysts plays a vital role in the fields of catalysis, sensing, and medical treatment due to the integrated advantages in the high activity of natural enzymes and the excellent stability of nanozymes. Herein, a new nanozyme/natural enzyme hybrid biosensor was established for ultrasensitive glutamate detection. The MIL-88B(Fe)-NH2 material with remarkable peroxidase mimic activity and stability was used as a nanozyme and carrier for immobilizing glutamate oxidase (GLOX) through Schiff base reaction to construct a chem-enzyme cascade detector (MIL-88B(Fe)-NH2@GLOX). The resultant MIL-88B(Fe)-NH2@GLOX exhibited a wide linear range (1–100 μM), with a low detection limit of 2.5 μM for glutamate detection. Furthermore, the MIL-88B(Fe)-NH2@GLOX displayed excellent reusability and storage stability. After repeated seven cycles, MIL-88B(Fe)-NH2-GLOX (GLOX was adsorbed on MIL-88B(Fe)-NH2) lost most of its activity, whereas MIL-88B(Fe)-NH2@GLOX still retained 69% of its initial activity. Meanwhile, MIL-88B(Fe)-NH2@GLOX maintained 60% of its initial activity after storage for 90 days, while free GLOX only retained 30% of its initial activity. This strategy of integrating MOF mimics and natural enzymes for cascade catalysis makes it possible to design an efficient and stable chemo-enzyme composite catalysts, which are promising for applications in biosensing and biomimetic catalysis.