Polyethylenimine-grafted and HSA-immobilized poly(GMA-MMA) affinity adsorbents for bilirubin removal

Abstract

The epoxy-group-containing microspheres from cross-linked glycidyl methacrylate and methyl methacrylate, poly(GAM-MMA), were prepared by suspension polymerisation. The epoxy groups of the poly(GMA-MMA) microspheres were used for grafting with an anionic polymer polyethylenimine (PEI) to prepare non-specific affinity adsorbents (poly(GMA-MMA)-PEI) for bilirubin removal. The specificity of the poly(GMA-MMA)-PEI adsorbent to bilirubin was further increased by immobilization of human serum albumin (HSA) via adsorption onto PEI-grafted poly(GMA-MMA) adsorbent. Various amounts of HSA were immobilized on the poly(GMA-MMA)-PEI adsorbent by changing the medium pH and initial HSA concentration. The maximum HSA content was obtained at 68.3mg g-1 microspheres. The effects of pH, ionic strength, temperature and initial bilirubin concentration on the adsorption capacity of both adsorbents were investigated in a batch system. Separation of bilirubin from human serum was also investigated in a continuous-flow system. The bilirubin adsorption on the poly(GMA-MMA)-PEI and poly(GMA-MMA)-PEI-HSA was not well described by the Langmuir model, but obeyed the Freundlich isotherm model. The poly(GMA-MMA)-PEI affinity microspheres are stable when subjected to sanitization with sodium hydroxide after repeated adsorption-desorption cycles. © 2004 Society of Chemical Industry.