Shape-controlled synthesis of Fe3O4/CeO2hybrid octahedra for lipase immobilization

Fe3O4/CeO2 hybrid octahedra have been successfully synthesized on the large scale via a solvothermal route, which were confirmed by a series of modern analytical tools. The formation and evolution of Fe3O4/CeO2 hybrid octahedra were systematically investigated, and a kinetically induced anisotropic growth mechanism clearly contributes to the formation of the novel architecture. Because of the magnetic nature and unique surfaces, the as-prepared Fe3O4/CeO2 hybrid octahedra were employed as magnetic carriers for lipase immobilization. Our results indicated that the lipase loading amount on the magnetic Fe3O4/CeO2 nanoparticles was about 43.1 mg of protein per g. Hydrolytic activity tests revealed that the immobilized lipase retains about 92.4% of the free enzyme's activity. The reusability assay revealed that the immobilized lipase can be reused 3 times without marked loss of catalytic activity (<5%). Most importantly, the thermal, acid and alkali stabilities of immobilized lipase were strikingly improved. It is hoped that the Fe3O4/CeO2 hybrid octahedra may find applications in biotechnology and biocatalysis.