Magnetically steerable Fe3O4@Ni2+-NTA-polystyrene nanoparticles for the immobilization and separation of his6-protein

[Display omitted] •Ni2+-NTA-PS NPs encapsulated with magnetic Fe3O4 NPs were synthesized.•The morphology, size and encapsulation were confirmed using SEM, TEM and DLS.•The application of our system was proved by magnetic separation of his6-tag protein. We developed Ni2+-nitrilotriacetic acid (NTA) functionalized polystyrene (Ni2+-NTA-PS) nanoparticles encapsulated with magnetic Fe3O4 nanoparticles (Fe3O4@Ni2+-NTA-PS nanoparticles) via miniemulsion/solvent evaporation method for the affinity purification of his6-tag recombinant proteins. Fe3O4@Ni2+-NTA-PS nanoparticles have a high surface to volume ratio, which enhanced the protein immobilization efficiency through the specific interaction between his6-tag of protein and Ni2+-NTA end of the polymer. The potential of Fe3O4@Ni2+-NTA-PS nanoparticles is demonstrated by a direct comparison with commercially available Ni2+-NTA-magnetic beads in his6-protein immobilization and recovery. Furthermore, the practical application of Fe3O4@Ni2+-NTA-PS magnetic nanoparticles is illustrated in his6-protein separation from crude cell lysate.