Congo Red and Cu(II) carrying poly(ethylene glycol dimethacrylate hydroxyethyl methacrylate) microbeads as specific sorbents - Albumin adsorption/desorption

Poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) [poly(EGDMA-HEMA)] microbeads, in the size range 150-200 mu m, were produced by a modified suspension copolymerization of EGDMA and HEMA. Congo Red was attached covalently to the poly(EGDMA-HEMA) microbeads, then Cu(II) ions were incorporated within the microbeads by chelating with the immobilized dye molecules. Different amounts of Cu(II) ions [0.5-2.9 mg Cu(II)/g polymer] were conjugated on the microbeads by changing the initial concentration of Cu(II) ions, pH and ionic strength. Bovine serum albumin (BSA) adsorption on these microbeads from aqueous solutions containing different amounts of BSA at different pH and ionic strengths was investigated in batch reactors. The non-specific BSA adsorption on the poly(EGDMA-HEMA) microbeads was almost zero. Congo Red derivatization significantly increased the BSA adsorption (up to 90 mg BSA/g polymer). A further increase in the adsorption capacity (up to 136 mg BSA/g polymer) was observed when Cu(II) ions were incorporated. More than 90% of the adsorbed BSA was desorbed in 1 h in a desorption medium containing 0.5 M NaSCN at pH 8.0.