Efficient purification of His-tagged protein by superparamagnetic Fe3O4/Au-ANTA-Co2+ nanoparticles.

Superparamagnetic Fe3O4/Au nanoparticles were synthesized and surface modified with mercaptopropionic acid (MPA), followed by conjugating Nα,Nα-Bis(carboxymethyl)-l-lysine hydrate (ANTA) and subsequently chelating Co(2+). The resulting Fe3O4/Au-ANTA-Co(2+) nanoparticles have an average size of 210 nm in aqueous solution, and a magnetization of 36 emu/g, endowing the magnetic nanoparticles with excellent magnetic responsivity and dispersity. The Co(2+) ions in the magnetic nanoparticle shell provide docking site for histidine, and the Fe3O4/Au-ANTA-Co(2+) nanoparticles exhibit excellent performance in binding of a His-tagged protein with a binding capacity of 74 μg/mg. The magnetic nanoparticles show highly selective purification of the His-tagged protein from Escherichia coli lysate. Therefore, the obtained Fe3O4/Au-ANTA-Co(2+) nanoparticles exhibited excellent performance in the direct separation of His-tagged protein from cell lysate. Crown