Purification of immunoglobulin G from human plasma by metal‐chelate affinity chromatography

A new group of specific‐affinity beads with metal chelates as ligands and synthetic polymer beads as support matrices was prepared and tested. This study focused on developing metal‐chelated poly(hydroxyethyl methacrylate) (PHEMA) gel beads in a spherical form (100–150 μm in diameter) for the separation of immunoglobulin G (IgG) from human plasma. Crosslinked PHEMA gel beads were prepared by suspension polymerization. The metal‐complexing ligand L ‐histidine was then immobilized by covalent binding onto these gel beads. Different transition‐metal ions, including Zn(II), Ni(II), Co(II), and Cu(II), were chelated on these gel beads. An elemental analysis of immobilized L ‐histidine for nitrogen was estimated to be 401.9 μmol of L ‐histidine/g of PHEMA. The nonspecific IgG adsorption onto plain PHEMA gel beads was negligible (ca. 0.17 mg/g). Higher adsorption values (up to 3.5 mg/g) were obtained in which L ‐histidine‐immobilized PHEMA gel beads were used from aqueous solutions. A remarkable increase in the IgG adsorption capacities were achieved from human plasma with L ‐histidine‐immobilized gel beads (up to 44.8 mg/g). Further increases in the IgG adsorption capacities of the metal‐chelated gel beads were observed when human plasma was used (up to 79.6 mg/g). The metal‐chelate affinity gel beads allowed the one‐step separation of IgG from human plasma. The recognition range of metal ions for surface histidines from human plasma followed this order: Cu(II) > Ni(II) > Zn(II) > Co(II). IgG molecules could repeatedly be adsorbed and desorbed with these metal‐chelated PHEMA gel beads without a noticeable loss in their IgG adsorption capacity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1567–1572, 2003