Fabrication of Yolk–Shell Fe₃O₄@NiSiO₃/Ni Microspheres for Efficient Purification of Histidine-Rich Proteins

Magnetic materials perform well in the purification of histidine-rich proteins (His-proteins). In this work, a facile fabrication of yolk-shell magnetic Fe3O4@NiSiO3/Ni microspheres for the efficient purification of His-proteins has been reported. Yolk-shell Fe3O4@NiSiO3 microspheres were prepared via hydrothermal reaction. Then Ni nanoparticles (NPs) were loaded on Fe3O4@NiSiO3 microspheres after the adsorption and in situ reduction of nickel acetylacetonate. The yolk-shell Fe3O4@NiSiO3/Ni microspheres had a hierarchical flower-like structure and large cavities. The size of the cavity depended on the reaction time. This indicated that the microspheres had a large specific surface area for loading of more Ni NPs, which was crucial to the high His-protein adsorption capacity of Fe3O4@NiSiO3/Ni microspheres. Fe3O4@NiSiO3/Ni microspheres had a high adsorption capacity for bovine hemoglobin (BHb, 2822 mg/g), which was better than the values of other His-protein adsorbents. Fe3O4@NiSiO3/Ni microspheres still had a high BHb separation efficiency after seven separation cycles, indicating its good reusability and stability. Therefore, the as-prepared bifunctional yolk-shell Fe3O4@NiSiO3/Ni microspheres exhibited great practical application value for His-protein purification.