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.
Aminated n-HAP-g-polyacrylonitrile (n-HAP-g-APAN) particle brushes were developed for highly efficient heavy metal removal based on surface-initiated ATRP (SI-ATRP) and subsequent amination. An efficient one-step method for morphology controlled synthesis of ATRP initiator immobilized n-HAP (n-HAP-Br) was realized by using 2-bromoisobutyric acid as tetherable initiator. Uniform and individually dispersed n-HAP-Br NCs were obtained with controlled morphology and particle size by adding portion of water miscible organic solvents to rational adjusting aqueous dispersion medium. Aminated n-HAP-g-APAN displayed record-high adsorption capacity of heavy meatal ions due to the combined contributions of grafted APAN providing pendent amino diethylenepentamine as chelating groups and n-HAP core towards heavy metal ions (pure n-HAP of q e = 284.4 mg/g vs n-HAP-g-APAN of q e = 944.4 mg/g). The proposed one-step direct bromination of n-HAP strategy provides the preparation of uniform n-HAP NCs ready for polymer grafting and further fabrication of n-HAP-g-polymers via SI-ATRP for various applications depending on the characteristic of grafted polymers.
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