Synthesis of molecularly imprinted polymers based on boronate affinity for diol-containing macrolide antibiotics with hydrophobicity-balanced and pH-responsive cavities.

In this research, in order to separate and purify diol-containing macrolide antibiotics, like tylosin, from complex biological samples, molecularly imprinted polymer (MIP) based on boronate affinity for tylosin was synthesized by using precipitation polymerization method with 4-vinylphenylboronic acid (VPBA) and dimethyl aminoethyl methacrylate (DMAEMA) as pH-responsive functional monomers, and N,N'-methylene bisacrylamide (MBAA)/ ethylene glycol dimethacrylate (EGDMA) as the co-crosslinkers that balance the hydrophobicity of the MIP. The synthesized tylosin-MIP had the advantages of high adsorption capacity (120 mg/g), fast pH-responsiveness responsible for the accessibility of imprinted cavities, and high selectivity coefficient towards tylosin versus its analogues (2.8 versus spiramycin, 7.3 versus desmycosin) in an aqueous environment. The mechanism of boronate affinity between tylosin and VPBA in the form of charged hydrogen bonding was analyzed via density functional theory (DFT). MIPs were used to successfully separate diol-containing macrolides through molecularly imprinted solid phase extraction (MISPE). The results show that MIPs prepared in this method have a good application prospect in the separation and purification of the diol-containing macrolide antibiotics.