Selective binding and magnetic separation of histidine-tagged proteins using Ni2+-decorated Fe3O4/hydroxyapatite composite nanoparticles

Abstract Fe 3 O 4 /hydroxyapatite (Fe 3 O 4 /HAP) nanoparticles (NPs) were synthesized by hydrothermal method. The obtained NPs have excellent magnetic responsibility and can immobilize metal ions. After chelating Ni 2+ ions, Fe 3 O 4 /HAP-Ni 2+ NPs can be used to enrich histidine-tagged (His-tagged) proteins directly from the mixture of lysed cells. Results show that Fe 3 O 4 /HAP-Ni 2+ NPs present negligible nonspecific protein adsorption and high protein binding activity with the saturation capacity being 12.98 mmol/g. Their separation capcity towards His-tagged proteins was remained after 4 times recycling. They are especially suitable for rapid purification of His-tagged proteins.