Tetra-nickel substituted polyoxotungsate as an efficient sorbent for the isolation of His6-tagged proteins from cell lysate

By virtue of the flexible structure of polyoxometalates , Ni 2+ is encapsulated into trivacant lacunary tungstophosphate ligands by the form of [Ni 4 ] cluster to offer a tetra-nickel substituted polyoxotungsate K 6 Na 4 [Ni 4 (H 2 O) 2 (PW 9 O 34 ) 2 ] (Ni 4 P 2 ). The Ni 4 P 2 is then immobilized onto the surface of SiO 2 nanoparticles by self-assembly under electrostatic interactions to give the product of Ni 4 P 2 @SiO 2 composites. Due to the specific affinity between substituted Ni 2+ in the polyoxotungsate and the histidine residues of protein, Ni 4 P 2 @SiO 2 composites exhibit highly adsorption selectivity towards histidine protein. This Ni 4 P 2 @SiO 2 composite is of high stability, and SDS-PAGE assay indicates that it can be used repeatedly as an efficient sorbent for the isolation of His6-tagged proteins from cell lysate with improved performance when compared with commercial NTA-Ni 2+ column.