DES-PMMA-assisted preparation of D-Serine chiral imprinted polymers and its molecular recognition behavior

Chiral separation of D- and L-Serine is of great value in the fields of biopharmaceuticals. For this purpose, a D-Serine imprinted polymer was prepared by precipitation polymerization with the aid of deep eutectic solvent (DES) and crowding agent (polymethyl methacrylate, PMMA). The preparation conditions were optimized by a L 9 (3 4 ) orthogonal design. Structure characterization was performed by the FTIR, SEM, AFM and XPS techniques and adsorption selectivity and separation efficiency for this imprinted material investigated. The results showed that under the conditions of pH 5.0 and 303 K, the polymer exhibited maximum adsorption capacity, reaching 121.4 mg g -1 , with a selectivity factor as high as 11.87. When this D-serine-imprinted material was used as a chromatographic stationary phase to separate a mixture of D- and L-serine, the resolution achieved was 1.765, demonstrating high chiral separation efficiency. The high adsorption selectivity for the novel imprinted material might result from the synergistic effect of deep eutectic solvent with macromolecular crowding reagent during the preparation of the imprinted materials. One hand, deep eutectic solvent can stabilize the zwitterionic form of D-Serine ( + H 3 N-CH(CH 2 OH)-COO - ) and hence enhance the ionic interactions between the template and functional monomers and the stability of template-functional monomer complexes; on the other hand, crowding agents significantly improved the binding efficiency between the functional monomer and the template molecules during the pre-assembly stage through the "excluded volume effect". This synergy promotes to form higher density and more precise specific recognition sites during the synthesis of the imprinted polymer and to improve the adsorption selectivity of the material obtained.