Functionalized hollow silica nanospheres for His-tagged protein purification

Hollow silica nanospheres (NSs) with dual chelating groups have been successfully prepared for the affinity separation of recombinant proteins. First, thiol-functionalized hollow silica (SiO 2 -SH) NSs were prepared through a hydrothermal route. The SiO 2 -SH NSs have an average diameter of 45   nm, with shell thickness of 10   nm. Their Brunauer–Emmett–Teller (BET) surface area, pore volume and pore size are 261.0   m 2 /g, 0.72   cm 3 /g and 0.4   nm, respectively. Then hollow SiO 2 -SH NSs were further modified by conjugating iminodiacetic acid (IDA) to bear dual chelating groups ( SH and COOH). After chelating Ni 2+ , these hollow NSs with dual chelating groups were applied to purify histidine-tagged (His-tagged) proteins. Results show that these hollow NSs present negligible nonspecific adsorption and high protein binding, which are suitable for rapid purification of His-tagged proteins.