Macroporous Thermosensitive Imprinted Hydrogel for Recognition of Protein by Metal Coordinate Interaction

A thermosensitive macroporous hydrogel showing selectivity for the lysozyme was developed by an imprinting procedure that is based on metal coordinate interaction. A metal chelate monomer [N-(4-vinyl)-benzyl iminodiacetic acid] forming coordination complex with the template protein in the presence of Cu ions co-polymerized with N-isopropylacrylamide and acrylamide, using N,N-methylenebisacrylamide as the cross-linker to prepare the thermosensitive protein-imprinted hydrogel. The synergetic combination of the smart property of the macroporous thermosensitive hydrogel with the merits of the coordinate interaction improved the selectivity and adsorption capacity, with respect to template lysozyme. The macropores were created by the frozen polymerization, and the influences of frozen polymerization and the chelate monomer content on the hydrogel affinity were investigated. The imprinted hydrogel can respond not only to external stimuli, but also to the template protein with a certain degree of shrinking. In recognition of the protein, the interaction of the imprinted thermosensitive hydrogel to the protein can be switched between the coordinate effect and the electrostatic effect by adding or not adding Cu ions. Finally, this imprinted hydrogel was used to purify the template lysozyme from the mixture of proteins and the real sample, which demonstrated its high selectivity.