A type of raspberry-like silica composite with tunable nickel nanoparticles coverage towards nanocatalysis and protein adsorption

In this manuscript, a facile one-pot approach is utilized to construct nickel-ion-polydopamine (PDA) complex thin coatings on silica spheres, which can be carbonized in an inert atmosphere, without using any extra reductant, to a raspberry-like hybrid nanocomposite with well-dispersed metallic nickel embedded in PDA-derived thin carbon layers on silica spheres. Due to the nickel-ion-PDA complex precursor, the formed nickel nanoparticles are well-dispersed onto the surface of the SiO2 without obvious aggregation. In addition, the size and density of the nickel nanoparticles could be precisely controlled by adjusting the molar ratio of nickel salt and dopamine, or by changing the calcination temperature. The as-prepared SiO2@C-Ni hybrid was employed as a reaction catalyst to investigate the catalytic performance in the reduction of 4-NP. Moreover, the nickel metal decorated on SiO2 spheres was also suitable for application as a magnetic separable nanocarrier, since these displayed a strong affinity for His-tagged proteins (BHb). The targeted protein species was captured on the surface of the SiO2@C-Ni hybrid via specific metal affinity forces between polyhistidine groups and nickel nanoparticles. The product exhibited highly selective adsorption on human serum albumin and hemoglobin (HHb and HSA) from diluted human blood.