Protein-imprinted polymers with shape-memorable imprint cavities operating at physiological pH

A strategy in which shape-memorable imprint cavities are constructed using peptide crosslinker (PC) was recently developed and the two major challenges for protein-imprinted polymers, i.e, difficult template removal and low imprinting efficiency, were successfully overcome.. Unfortunately, these polymers fail to bind the target protein at physiological pH, which severely limits their applications. Herein a novel PC based on the copolymer of γ-(2-(2-(2-methoxyethoxy)ethoxy)ethyl L-glutamate (EG 3 Glu) and L-boronophenylalanine (BPA) was designed and synthesized. The PC adopts an α-helical conformation at physiological pH but converts to extended coil conformation at high pH values. Using it as crosslinker, BSA-imprinted polymer was synthesized. Because of the reversible and precise pH-induced helix-coil transition of the peptide segments, the template can be removed facilely by elution with pH 11.5 solution. Meanwhile high affinity towards the template protein BSA is achieved at physiological pH. Both imprinting factor (6.28) and adsorption capacity (965.57 mg/g) is significantly higher than the polymer crosslinked with the common crosslinker N,N’-methylenebisacrylamide (BIS). The polymer also demonstrates high selectivity towards BSA and excellent reusability.It was successfully used to remove BSA from mixed solution of BSA and lysozyme at physiological pH. Not only BSA was removed selectively and efficiently, but the bioactivity of lysozyme was not affected, because BSA removal was performed under very mild conditions, i.e., at physiological pH and room temperature.