Glutamate oxidase-integrated biomimetic Fe3O4 hybrids as cascade nanozymes for glutamate detection

Herein, a new nanozyme/natural enzyme hybrid biosensor was established for ultrasensitive l-glutamic acid (L-Glu) detection. The Fe ₃O ₄ nanoparticles with peroxidase-like activity and stability was used as a nanozyme and carrier for immobilizing l -Glutamate oxidase (GLOD) through Schiffff base reaction to construct a chem-enzyme cascade detector. The resultant Fe ₃O ₄-GOLD exhibited a wide linear range (10−500 μM) and a low detection limit of 6.03 μM for L-Glu detection. Furthermore, the Fe ₃O ₄ -GOLD exhibited excellent pH stability, thermal stability, reusability and storage stability. After repeated nine cycles, Fe ₃O ₄-GOLD still retained 70% of its initial activity. Meanwhile, Fe ₃O ₄ -GOLD maintained 50% of its initial activity after storage for 20 days, while free GLOD only retained 20% of its initial activity. This strategy of integrating biomimetic Fe ₃O ₄ 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.