Nano-hard template synthesis of pure mesoporous NiO and its application for streptavidin protein immobilization.

A simple and efficient immobilization of streptavidin protein (with hexa-histidine tag) onto the surface of mesoporous NiO is described. Before immobilization of streptavidin protein (with hexa-histidine tag) onto the surface of mesoporous NiO, we first synthesized well-organized mesoporous NiO by a nanocasting method using mesoporous silica SBA-15 as the hard template. Then, the well-organized mesoporous NiO particles were characterized by small angle x-ray diffraction (XRD), wide angle XRD, nitrogen adsorption/desorption, and transmission electron microscopy (TEM). TEM and small angle XRD suggested the formation of mesoporous NiO materials, whereas the wide angle XRD pattern of mesoporous NiO indicated that the nickel precursor had been transformed into crystalline NiO. The N2 sorption experiments demonstrated that the mesoporous NiO particles had a high surface area of 281 m2 g(-1), a pore volume of 0.51 cm3 g(-1) and a pore size of 4.8 nm. Next, the immobilization of streptavidin protein (with hexa-histidine tag) onto the surface of mesoporous NiO was studied. Detailed analysis using gel electrophoresis confirmed that this approach can efficiently bind his-tagged streptavidin onto the surface of mesoporous NiO material since the mesoporous NiO provides sufficient surface sites for the binding of streptavidin via non-covalent ligand binding with the histidine tag.