Supermacroporous poly(hydroxyethyl methacrylate) based cryogel with embedded bilirubin imprinted particles

Molecular imprinted polymers are artificial, template-made materials with the ability to recognize and to specifically bind the target molecule. The aim of this study is to prepare supermacroporous cryogel with embedded bilirubin-imprinted particles which can be used for the selective removal of bilirubin from human plasma. N-methacryloyl-(l)-tyrosinemethylester (MAT) was chosen as the pre-organization monomer. In the first step, bilirubin was complexed with MAT and the bilirubin-imprinted poly(hydroxyethyl methacrylate-N-methacryloly-(l)-tyrosine methyl-ester) [MIP] monolith was produced by bulk polymerization. MIP monolith was smashed and the particles ground and sieved through 100 μm sieves. In the second step, the supermacroporous poly(hydroxyethyl methacrylate) (PHEMA) cryogel with embedded MIP particles [PHEMA/MIP composite cryogel] was produced by free radical polymerization initiated by N,N,N′,N′-tetramethylene diamine (TEMED) and ammonium persulfate (APS) pair in an ice bath. After that, the template (i.e., bilirubin) molecules were removed using sodium carbonate and sodium hydroxide. Compared with the PHEMA cryogel (0.2 mg/g polymer), the bilirubin adsorption capacity of the PHEMA/MIP composite cryogel (10.3 mg/g polymer) was improved significantly due to the embedded MIP particles into the polymeric matrix. The relative selectivity coefficients of PHEMA/MIP composite cryogel for bilirubin/cholesterol and bilirubin/testosterone were 8.6 and 4.1 times greater than the PHEMA cryogel, respectively. The PHEMA/MIP composite cryogel could be used many times without decreasing the bilirubin adsorption capacity significantly.