Improvement of the stability and activity of immobilized glucose oxidase on modified iron oxide magnetic nanoparticles

•Modified iron oxide magnetic nanoparticles were synthesized by co-precipitation method and characterized by TEM and XRD.•Covalent attachment of GOX to MIMNs was confirmed by FT-IR technique.•Optimization of the reaction time and initial amount of the GOX were carried out.•Improvement of activity and stability of immobilized GOX have been increased in comparison of free GOX. Immobilized proteins and enzymes are widely investigated in the medical field as well as the food and environmental fields. In this study, glucose oxidase (GOX) was covalently immobilized on the surface of modified iron oxide magnetic nanoparticles (MIMNs) to produce a bioconjugate complex. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to the size, shape and structure characterization of the MIMNs. Binding of GOX to these MIMNs was confirmed by using FT-IR spectroscopy. The stability of the immobilized and free enzyme at different temperature and pH values was investigated by measuring the enzymatic activity. These studies reveal that the enzyme's stability is enhanced by immobilization. Further experiments showed that the storage stability of the enzyme is improved upon binding to the MIMNs. The results of kinetic measurements suggest that the effect of the immobilization process on substrate and product diffusion is small. Such bioconjugates can be considered as a catalytic nanodevice for accelerating the glucose oxidation reaction for biotechnological purposes.