Fabrication of graphene oxide decorated with FeO@SiO for immobilization of cellulase

FeO@SiO–graphene oxide (GO) composites were successfully fabricated by chemical binding of functional FeO@SiO and GO and applied to immobilization of cellulase via covalent attachment. The prepared composites were further characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. FeO nanoparticles (NPs) were monodisperse spheres with a mean diameter of 17 ± 0.2 nm. The thickness of SiO layer was calculated as being 6.5 ± 0.2 nm. The size of FeO@SiO NPs was 24 ± 0.3 nm, similar to that of FeO@SiO–NH. FeO@SiO–GO composites were synthesized by linking of FeO@SiO–NH NPs to GO with the catalysis of EDC and NHS. The prepared composites were used for immobilization of cellulase. A high immobilization yield and efficiency of above 90 % were obtained after the optimization. The half-life of immobilized cellulase (722 min) was 3.34-fold higher than that of free enzyme (216 min) at 50 °C. Compared with the free cellulase, the optimal temperature of the immobilized enzyme was not changed; but the optimal pH was shifted from 5.0 to 4.0, and the thermal stability was enhanced. The immobilized cellulase could be easily separated and reused under magnetic field. These results strongly indicate that the cellulase immobilized onto the FeO@SiO–GO composite has potential applications in the production of bioethanol.