| Abstract: | Employing immobilized metal‐ion affinity chromatography and magnetic separation could ideally provide a useful analytical strategy for purifying His‐tagged protein. In the current study, a facile route was designed to prepare CMPEI‐Ni2+@SiO2@Fe3O4 (CMPEI=carboxymethylated polyethyleneimine) magnetic nanoparticles composed of a strong magnetic core of Fe3O4 and a Ni2+‐immobilized carboxymethylated polyethyleneimine coated outside shell, which was formed by electrostatic interactions between polyanionic electrolyte of carboxymethylated polyethyleneimine and positively charged surface of 3‐(trimethoxysilyl)propylamin modified SiO2@Fe3O4. The resulting CMPEI‐Ni2+@SiO2@Fe3O4 composite nanoparticles displayed well‐uniform structure and high magnetic responsiveness. Hexa His‐tagged peptides and purified His‐tagged recombinant retinoid X receptor alpha were chosen as the model samples to evaluate the adsorption, capacity, and reusability of the composite nanoparticles. The results demonstrated the CMPEI‐Ni2+@SiO2@Fe3O4 nanoparticles possessed rapid adsorption, large capacity, and good recyclability. The obtained nanoparticles were further used to purify His‐tagged protein in practical environment. It was found that the nanoparticles could selectively capture His‐tagged recombinant retinoid X receptor protein from complex cell lysate. Owing to its easy synthesis, large binding capacity, and good reusability, the prepared CMPEI‐Ni2+@SiO2@Fe3O4 magnetic nanoparticles have great potential for application in biotechnological fields. |
