Abstract:A one-step hydrothermal procedure to form Fe₃O₄ nanospheres on chemically reduced graphene oxide (CRGO) surfaces was proposed, and these nanocomposites were used as substrates for enzyme immobilization. The as-prepared Fe₃O₄/CRGO nanocomposites were characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), FT-IR and vibrating sample magnetometer. Fe₃O₄ microspheres are randomly distributed on graphene sheets, and the average diameter of Fe₃O₄ microspheres is about 260 nm. Horseradish peroxidase (HRP) was used as a model enzyme to investigate the immobilization activity. The HRP loading was 23.3 mg/g supports and retained 70% of the first use after ten cycles. The catalyzed capability of immobilized HRP was investigated and the immobilized HRP exhibited broader pH stability and excellent reusability. The results show that the Fe₃O₄/CRGO nanocomposites are appropriate for the immobilization of enzyme, and could have potential use in practical.

Key words: chemically reduced graphene oxide (CRGO); Fe₃O₄; horseradish peroxidase (HRP); enzyme immobilization