Molecularly Imprinted Polymer with High Capacity and Selectivity for Separation of Bovine Serum Albumin

A cost-effective but simple method for the separation of bovine serum albumin (BSA) from complex biological fluids is still lacking. Here using N-isopropylacrylamide as the main monomer and dimethylaminoethyl methacrylate, methacrylic acid, and acrylamide as functional monomers, a BSA-imprinted polymer was synthesized. To overcome the two major obstacles of common protein-imprinted polymers, i.e., difficult template removal and low imprinting efficiency, an oligo(glutamic acid)-based peptide cross-linker with the same vinyl group on both ends was designed and used as cross-linker in the synthesis of the polymers. The introduction of the peptide segments, which are capable of undergoing a pH-triggered reversible and precise helix–coil transition, into the polymers makes the imprint cavities shape-memorable. Therefore, complete removal of the template BSA under mild conditions, that is, at physiological pH, ionic strength, and temperature, was achieved. More importantly, an adsorption capacity of 607 mg/g and an imprinting factor of 6.0, both of which are not only higher than the molecularly imprinted polymer (MIP) cross-linked with the commonly used cross-linker N,N′-methylenebis(acrylamide), but also higher than most BSA MIPs reported previously in the literature, were obtained, indicating a high affinity of the MIP to the template BSA. The BSA MIP also showed a high selectivity and could be used repeatedly. Using the BSA MIP as the adsorbent, BSA was extracted from fetal bovine serum selectively and efficiently.