pH and temperature dual-sensitive molecular imprint polymers for BSA based on Cu²⁺ coordination

A novel kind of pH and temperature dual-sensitive Molecular imprint polymers (MIPs) combined with Cu²⁺ coordination (SiO₂@CS/NIPAM-Cu²⁺-MIP) has been synthesized using glycidyl methacrylate-iminodiacetic acid (GMA-IDA) as a metal chelating ligand, with bovine serum albumin (BSA) as template protein, combined with pNIPAM and chiston (CS) as temperature and pH sensitive monomers, respectively. The coordination effect of GMA-IDA-Cu²⁺ has been shown to be beneficial to improve the adsorption capacity and adsorption specificity of BSA. The influence of pH not only changed the charge force between the polymer and protein in the imprinting system, but also deformed the imprinting cavity through the protonation of NH₃⁺ on CS. Further, the thermo-sensitivity of the imprinted polymer was also found to be satisfactory. With the joint efforts of coordination, electrostatic action and good matching of imprinted sites, higher adsorption capacity (173.48 mg∙g^-1) and imprinting factor (2.72) have been obtained at pH 4.6 and 35ºC. Although it took about 4 h to reach saturation adsorption, the cyclability of the SiO₂@CS/NIPAM-Cu²⁺-MIP was found to be acceptable and the adsorption capacity was maintained at original 81.16% after six cycles. It is for the first time that GMA-IDA-Cu²⁺ has been used to prepare the pH and temperature dual-sensitive imprinted polymer for BSA.