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 (SiO2-SH) NSs were prepared through a hydrothermal route. The SiO2-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 m2/g, 0.72 cm3/g and 0.4 nm, respectively. Then hollow SiO2-SH NSs were further modified by conjugating iminodiacetic acid (IDA) to bear dual chelating groups (SH and COOH). After chelating Ni2+, 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.