Preparation of surface molecularly imprinted polymeric microspheres and their recognition property for basic protein lysozyme

The surface imprinting of basic protein lysozyme (Lys) was carried out by designing a new route. The copolymerization of N-vinylpyrrolidone (NVP) and 2-hydroxyethyl methacrylate (HEMA) was first conducted in an inverse suspension polymerization system, and the crosslinked copolymeric microspheres HEMA/NVP were prepared. Subsequently, the esterification reaction of methacryloyl (MAO) chloride with the hydroxyl groups on the surfaces of HEMA/NVP microspheres was performed, and the modified microspheres MAO–HEMA/NVP, on which a mass of polymerisable double bonds were introduced, were obtained. In the presence of lysozyme, by initiating of K2S2O8–NaHSO3, the monomer methacrylic acid (MAA) in the solution was crosslink-polymerized on the surfaces of MAO–HEMA/NVP microspheres, resulting in the surface imprinting of lysozyme. After removing the template molecules, the lysozyme molecule-surface-imprinted material MIP-HEMA/NVP was obtained. Because there were strong interactions between lysozyme and monomer MAA, electrostatic interaction and hydrogen bonding, the lysozyme molecule-surface imprinting was successfully realized. The MIP-HEMA/NVP microspheres have very high binding affinity for lysozyme, and the binding capacity gets up to 216 mg/g. It is more important that MIP-HEMA/NVP microspheres have specific recognition selectivity for lysozyme, and the selectivity coefficient for lysozyme with respect to bovine hemoglobin (BHb), which was used as a contrast protein in the experiments, actually reaches 31.07. In the respect of protein imprinting, the imprinting material with such high performance is unwonted.