Selective and fast separation of BSA using surface-imprinted polymer under mild conditions

It still remains a big challenge to separate a target protein from a complicated biological samples selectively. Here BSA-imprinted silica nanoparticles were synthesized by combining several new strategies. Firstly, a novel surface enzyme-initiated polymerization was used to synthesize the imprinted polymer shell over nanoparticles. Particle agglomeration, a key problem for conventional surface imprinting, was successfully avoided, even when high concentration prepolymerization solutions were used. Therefore high imprinting efficiency was achieved because of the enhanced pre-assembly between the template and functional monomers. Secondly, the “shape-memory imprint cavity” strategy was used in which a peptide crosslinker capable of undergoing pH-induced helix-coil transition was used as crosslinker. This strategy not only facilitate the removal of template protein, but also significantly improve imprinting efficiency. In addition, to rebind protein at physiological pH, a new peptide crosslinker which adopts an α-helical conformation at physiological pH but converts to extended coil conformation at high pHs was used. The resulting BSA-imprinted silica nanoparticles exhibited high adsorption capacity (119.7 mg g −1 ), high imprinting factor (8.86), high selectivity, good reusability, and rapid binding kinetics. The particles can separate BSA from mixed protein solutions and even complex serum samples selectively, efficiently and quickly. More importantly, because the process was performed under very mild conditions, i.e., at room temperature and in aqueous solution with physiological pH, the biological activity of the remaining proteins was not affected.