Cu(II)-incorporated, histidine-containing, magnetic-metal-complexing beads as specific sorbents for the metal chelate affinity of albumin

N-Methacryloyl-(L)-histidine methyl ester (MAH) was synthesized from metharyloyl chloride and histidine. Spherical beads with an average size of 150-250 μm were obtained by the suspension polymerization of ethylene glycol dimethacrylate and MAH in an aqueous dispersion medium. Magnetic polyethylene glycol dimethacrylate-co-N-Methacryloyl-(L)-histidine methyl ester) [m-p(EGDMA-co-MAH)] microbeads were characterized with swelling tests, electron spin resonance, elemental analysis, and scanning electron microscopy. The specific surface area of the beads was 80.1 m²/g. m-p(EGDMA-co-MAH) microbeads with a swelling ratio of 40.2% and 43.9 μmol of MAH/g were used for the adsorption of bovine serum albumin (BSA) in a batch system. The Cu(II) concentration was 4.1 μmol/g. The adsorption capacity of BSA on the Cu(II)-incorporated beads was 19.2 mg of BSA/g. The BSA adsorption first increased with the BSA concentration and then reached a plateau, which was about 19.2 mg of BSA/g. The maximum adsorption was observed at pH 5.0, which was the isoelectric point of BSA. The BSA adsorption increased with decreasing temperature, and the maximum adsorption was achieved at 4°C. High desorption ratios (>90% of the adsorbed BSA) were^pwith 1.0M NaSCN (pH 8.0) in 30 min. The nonspecific adsorption of BSA onto the mp(EGDMA-co-MAH) beads was negligible.