Silane‐Modified Magnetic Beads: Application to Immunoglobulin G Separation

Abstract The magnetic poly(2‐hydroxyethyl methacrylate ethylene glycol dimethacrylate) [ m ‐poly(HEMA‐EGDMA)] beads (150–250‐μm diameter in spherical form) were prepared by a radical suspension polymerization technique. The pseudo‐specific ligand, reactive imidazole containing 3–(2‐imidazoline‐1‐yl)propyl (triethoxysilane) (IMEO) was selected as a silanization agent. IMEO was covalently immobilized onto the magnetic beads. IMEO‐immobilized m ‐poly(HEMA‐EGDMA) beads were used for the affinity adsorption of immunoglobulin‐G (IgG) from aqueous solutions and human plasma. To evaluate the degree of IMEO attachment, the m ‐poly(HEMA‐EGDMA) beads were subjected to Si analysis by using flame atomizer atomic absorption spectrometer, and it was estimated as 36.6 mg IMEO/g of polymer. The nonspecific IgG adsorption onto the plain m ‐poly(HEMA‐EGDMA) beads was very low (about 0.4 mg/g). Higher adsorption values (up to 55 mg/g) were obtained when the m ‐poly(HEMA‐EGDMA)/IMEO beads were used from both aqueous solutions and human plasma. The maximum IgG adsorption on the m ‐poly(HEMA‐EGDMA)‐IMEO beads was observed at pH 7.0. The IgG molecules could be repeatedly adsorbed and desorbed with m ‐poly(HEMA‐EGDMA)‐IMEO beads without noticeable loss in the IgG adsorption capacity. The adsorption capacity from human plasma in magnetically stabilized fluidized bed decreased drastically from 78.9 to 19.6 mg/g with the increase of the flow rate from 0.2 to 3.5 mL/min.