Glutamate oxidase-integrated biomimetic Fe_(3)O_(4) 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_(3)O_(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_(3)O_(4)-GOLD exhibited a wide linear range(10−500μM)and a low detection limit of 6.03μM for L-Glu detection.Furthermore,the Fe_(3)O_(4)-GOLD exhibited excellent pH stability,thermal stability,reusability and storage stability.After repeated nine cycles,Fe_(3)O_(4)-GOLD still retained 70%of its initial activity.Meanwhile,Fe_(3)O_(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 3 O4 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.

A dual enzyme-phosphate hybrid nanoflower for glutamate detection

The enzyme hybrid nanoflower has gained interests in biosensors due to their simple synthesis and high efficiency.In this study,glutamate oxidase(GLOX)and horseradish peroxidase(HRP)hybrid nanoflowers(GLOX&HRP-HNFs)were successfully prepared for the detection of glutamic acid(Glu).The effects of the synthesis conditions on the activity of GLOX&HRP-HNFs were investigated.Results revealed that the maximum activity of GLOX&HRP-HNFs was under 4 mM phosphate radical,2.5 mM MnSO4,0.04 mg/mL GLOX,and 0.16 mg/mL HRP.After immobilization,no significant differences were observed in optimum pH and temperature values of the GLOX and HRP.The GLOX&HRP-HNFs exhibited higher storage stability and resistance to organic solvents than free GLOX and HRP.Additionally,the GLOX&HRP-HNFs maintained 69%of its primary activity after 6 cycles.More important,the GLOX&HRP-HNFs exhibited a good linear range from 1 to 100μM(R^(2)=0.9979)and a low limit of detection(LOD)of 0.59μM for glutamate.These results suggest that the GLOX&HRP-HNFs is a promising candidate for applications in biosensing for the detection of glutamate.