Covalent immobilization of glucose dehydrogenase onto graphene oxide magnetic nanoparticles to improve the stability

Glucose dehydrogenase, as an important biocatalyst, has been widely used in biosensors, especially in measuring blood glucose levels. The low stability of the enzyme limits its applications in clinics and industry. To improve the stability, graphene oxide nanoparticles were fabricated, characterized, and used to immobilize of glucose dehydrogenase. The nanoparticles were characterized by FTIR. The enzyme was covalently immobilized on the nanoparticles with the activation of glutaraldehyde. After optimizing the immobilization conditions, an immobilization yield of 92% and the activity recovery of 91% were achieved. The immobilized GDH was characterized and compared with the free enzyme. It showed 6.9-fold higher stability than that of the free enzyme after the immobilization. And after 25 cycles, the immobilized GDH remained 50% of the initial activity. These results indicated that the immobilization could broaden the applications of the GDH in the industry and clinic.