Molecularly Imprinted Polymer Microspheres Prepared by Precipitation Polymerization for the Binding and Recognition of Roxithromycin

In the presence of a template molecule, roxithromycin (RM), novel molecularly imprinted polymer (MIP) microspheres were prepared by one-step precipitation polymerization using methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA) and 2´2-azobisisobutyronitrile (AIBN) as functional monomer, cross-linker and initiator, respectively. The scanning electron microscopy exhibited that the imprinted polymers synthesized were uniform spheres with the diameter of about 3μm. The results of equilibrium rebinding experiments showed that the binding ability of imprinted microspheres to RM was much higher than that of non-imprinted ones and the imprinted polymers possessed a fast adsorption dynamics. Scatchard plot analysis revealed that there were two types of binding sites formed in the imprinted polymer microspheres. The dissociation constant and the apparent maximum binding capacity were 2.63×10^-2μmol/mL and 14.65μmol/g for the high affinity binding sites and 1.05 μmol/mL, 83.16μmol/g for the low affinity binding sites. The specificity of the imprinted microspheres was investigated by binding analysis with RM and its analogues, erythromycin (EM), azithromycin (AM) and erythromycin ethylsuccinate (EE). Compared to those three structurally similar compounds, the imprinted microspheres exhibited a high selective recognizable capacity towards the template. The results of this study implied that the obtained imprinted microspheres can be utilized as specific absorbents for the separation, enrichment, and analysis of roxithromycin in environmental water or food.