Preparation of hollow nickel silicate nanospheres for separation of His-tagged proteins

Hollow nickel silicate nanospheres (NiSiO3 NSs) with hierarchical shells were hydrothermally synthesized by using silica spheres as a template. The NiSiO3 NSs have an average diameter of 250 nm with a shell thickness of 50 nm, and the hierarchical shell consists of a large number of sheets. By taking advantage of the high affinity of Ni(2+) toward histidine-tagged (His-tagged) proteins, hollow NiSiO3 NSs can be used to enrich and separate His-tagged proteins directly from a mixture of lysed cells. Results indicated that the hollow NiSiO3 NSs presented negligible nonspecific protein adsorption and a high protein binding ability with a high binding capacity of 13.2 mmol g(-1). Their specificity and affinity toward His-tagged proteins remained after recycling 5 times. The hollow NiSiO3 NSs are especially suitable for rapid purification of His-tagged proteins.