Rational Engineering of Copper Ion-Coordinated Molecularly Imprinted Polymers for Synergistic Enhancement of Protein Recognition and Separation

By creating tailor-made binding sites, molecularly imprinted polymers (MIPs) function as synthetic antibodies, offering comparable specificity with enhanced stability and lower cost. While molecular imprinting technology has achieved significant success with small molecules, its application to macromolecules such as proteins remains challenging. This is primarily due to the common use of aqueous solutions for protein imprinting, where key interactions like hydrogen bonding and electrostatic forces are significantly weakened. To address these limitations, this study reports the rational design of a Cu(II)-coordinated MIPs nanocavity for the efficient and selective adsorption of bovine serum albumin (BSA). The approach leverages the chelation between histidine residues on the surface of BSA and Cu(II), in conjunction with the primary monomer <i>N</i>-isopropylacrylamide (NIPAM) and various functional monomers, including acrylamide (AAM), dimethylaminoethyl methacrylate (DMAEMA), 4-vinylpyridine (4-Vpy), and methacrylic acid (MAA), to construct a shape memory characteristic imprinted nanocavity. Notably, polyglutamic acid peptide cross-linkers (PC) were employed in place of conventional cross-linkers, through a pH-induced helical-coil conformational change, they allow for the gentle yet complete extraction of the BSA template. Experimental results demonstrated that the incorporation of Cu(II) improved the imprinting effect, with the Cu(II)-containing hydrogel achieving an adsorption capacity of 757.5 mg/g and an imprinting factor (IF) of 5.28. Mechanistic analysis revealed that the coordination of Cu(II) synergistically combines the strength of covalent bonds with the flexibility of noncovalent interactions, while the dynamic structure of the PC enhances the specificity of the imprinted sites. Separation experiments conducted with actual serum samples validated the high selectivity of this material for BSA. This research introduces a strategy for protein molecular imprinting technology that integrates high adsorption performance with mild desorption conditions, suggesting significant potential applications in the fields of biomedicine and blood analysis.