Regulation of protein-binding activities of molecularly imprinted polymers via post-imprinting modifications to exchange functional groups within the imprinted cavity.

We prepared lysozyme-imprinted polymers bearing modifiable sites within the imprinted cavity to introduce various functional groups via post-imprinting modifications. For this purpose, ({[2-(2-methacrylamido)-ethyldithio]-ethylcarbamoyl}-methoxy)acetic acid (MDTA), which has a carboxy group to interact with the target protein, lysozyme, and a disulfide linkage for post-imprinting modifications, was used as a functional monomer. A lysozyme-imprinted polymer film was prepared by copolymerization of MDTA with a cross-linker, N,N'-methylenebisacrylamide, in the presence of lysozyme. After removing lysozyme, followed by reducing the disulfide linkage, various functional groups, such as carboxy, amino, sulfonate, and oligo-ethylene oxide, were introduced to the exposed thiol groups via a disulfide exchange reaction using the pyridyldisulfide derivatives of these functional groups. Various functional groups could be introduced reversibly via this post-imprinting disulfide exchange reaction after the construction of the lysozyme-imprinted cavities. The modification regulated the protein-binding activity. The proposed post-imprinting modification system, based on a molecular imprinting process, is expected to lead to the development of advanced materials for fine-tuning and/or introducing desired functions.