Binding specificity of α-bilirubin-imprinted poly(methacrylic acid-co-ethylene glycol dimethylacrylate) toward α-bilirubin

α-Bilirubin is an important index to determine the liver's functions. Poly(methacrylic acid-co-ethylene glycol dimethylacrylate) (poly(MAA-co-EGDMA)) imprinted with α-bilirubin was proposed and shown to be able to bind α-bilirubin specifically. The extraction condition was also discussed. Polymers prepared by imprinting bilirubin in poly(MAA-co-EGDMA) and in poly(β-cyclodextrin-co-EGDMA) were compared. In this work, binding specificity of molecularly imprinted polymer (MIP) toward the target template, α-bilirubin, is discussed. Adsorption profile of α-bilirubin by bilirubin-imprinted poly(MAA-co-EGDMA) was measured as a function of time, from where the equilibrium could be determined. Two hours was determined to be the proper time for adsorption. Biliverdin as a rather similar analog compound of bilirubin was chosen for comparison of binding specificity in this study. Progesterone as well as testosterone was also chosen for study because they both co-exist in serum with bilirubin and might interfere with binding capacity of imprinted poly(MAA-co-EGDMA) toward α-bilirubin. Specificity of this polymer for bilirubin was thus confirmed by tasks carried out in mixture solutions comprised of compounds above. It is true that biliverdin contained in the binary mixture did affect the binding capacity of bilirubin. Nevertheless, polymer's binding specificity for bilirubin was essentially sufficient for recognition of α-bilirubin in the presence of other compounds. How MIP identified the target template molecule, α-bilirubin, is also elucidated.