Ferroferric oxide/l-cysteine magnetic nanospheres for capturing histidine-tagged proteins.

Ferroferric oxide/l-cysteine (Fe3O4/Cys) nanospheres (NSs) have been successfully synthesized via a facile solvothermal route. Fe3O4/Cys NSs possessed high thiol group density and saturation magnetization (Ms) of 84.6 emu g-1. The prepared magnetic NSs are biocompatible and manipulatable by an external magnetic force. After chelating Ni2+ ions, Fe3O4/Cys-Ni2+ NSs were used to enrich and purify histidine-tagged (His-tagged) proteins directly from the mixture of lysed cells without pretreatment. It has been found that Fe3O4/Cys-Ni2+ NSs present negligible nonspecific protein adsorption and high protein binding activity with the saturation capacity being 53.2 μg mg-1 and they are especially suitable for rapid purification of His-tagged proteins.