Porous magnetic chelator support for albumin adsorption by immobilized metal affinity separation

Magnetic poly(2-hydroxyethylmethacrylate) (mPHEMA) beads are modified by iminodiacetic acid (IDA) to implify the reactive groups and subsequent binding of Cu²⁺ ions to form metal chelate. mPHEMA beads, in the size range of 80-120 μm, were produced by a modified suspension polymerization technique. mPHEMA beads were characterized by swelling tests, electron spin resonance (ESR), FTIR, and scanning electron microscopy (SEM). Important results obtained in this study are as follows. The swelling ratio of mPHEMA beads was 34%. The presence of magnetite particles in the polymeric structure was confirmed by ESR. FTIR data confirmed that the magnetic polymer beads were modified with functional groups IDA. The mPHEMA beads have a spherical shape and porous structure. The effect of pH and concentration of human serum albumin (HSA), on the adsorption of HSA to the metal-chelated magnetic beads, were examined in a batch reactor. Most importantly, the magnetic beads had little nonspecific adsorption for HSA (0.5 mg/g) before introducing IDA groups. Cu chelation increased the HSA adsorption up to 28.4 mg/g. Adsorption behavior can be described at least approximately with the Langmuir equation. Regeneration of the metal-chelated magnetic beads was easily performed with 1.0M NaSCN, pH 8.0, followed by washing with distilled water and reloading with Cu²⁺.