High Affinity BSA-imprinted polymers with long-chain alkyl ionic liquid functional monomers

Functional monomers play a key role in protein-imprinted polymers. Inspired by the ability of albumin to bind and deliver lipids, imidazolium-based ionic liquid (IL) monomers with an allyl group and a long chain alkyl group were selected as cationic functional monomer for synthesis of molecularly imprinted polymers (MIPs) of BSA. The “shape-memorable imprint cavity” strategy, which uses peptide crosslinkers (PCs) to construct shape-memorable imprint cavities, was also adopted. Fluorescence quenching demonstrated that the IL monomers have a larger binding constant with BSA than the conventional cationic monomer DMAEMA, because they bind with BSA via not only electrostatic interaction but also hydrophobic force due to their long-chain alkyl group. In addition, with increasing length of the alkyl group, the IL monomers bind with BSA more strongly. Compared with the BSA MIP using DMAEMA, significantly improved imprinting efficiency was observed when using the IL monomers as cationic monomers. Particularly the MIP using [C 8 VIm]Br exhibits an adsorption capacity of 983.90 mg/g and an imprinting factor of 7.76. The selectivity of the MIP towards BSA was also improved. In addition, like other MIPs using the “shape-memorable imprint cavity” strategy, the new BSA MIPs also exhibit advantages such as complete template removal under mild conditions and excellent reusability. The new BSA MIP was successfully used to extract BSA from fetal bovine serum, demonstrating its high potential for the separation and purification of BSA from complicated biological fluids.