Nickel hydroxide/hydroxyapatite nanorods as affinity adsorbents for separation histidine-tagged proteins

Nickel hydroxide/hydroxyapatite (designated as Ni(OH)2/HAP) nanorods have been designed and synthesized by hydrothermal method. The size and morphology of Ni(OH)2/HAP sample depend strongly on the reaction condition, and introduction of small amount of Ni2+ ions would be propitious to get the smaller size nanorods. By taking advantage of the high affinity of Ni2+ ions toward histidine-tagged (His-tagged) proteins, the Ni(OH)2/HAP nanorods can be used to enrich and separate His-tagged proteins directly from a mixture of lysed cells, and their universality was evaluated by separating three kinds of His-tagged proteins. The Ni(OH)2/HAP nanorods present negligible nonspecific protein adsorption and high protein binding ability, and their specificity and affinity toward His-tagged proteins can be remained after 4 times recycling. The Ni(OH)2/HAP nanorods may provide many potential applications for the detection or separation of different biomolecules.