Immunoglobulin G adsorption behavior of l-histidine ligand attached and Lewis metal ions chelated affinity membranes

Immobilized metal affinity membranes were prepared by chelating Cu(II) and Fe(III) ions on poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), poly(HEMA-GMA) membranes using l-histidine as a chelating ligand. To achieve this goal, the poly(HEMA-GMA) membrane was prepared via UV initiated photopolymerization. A spacer-arm (i.e., 1,6-diaminohexane) was introduced through the epoxy groups of the membrane (poly(HEMA-GMA)-SA). A chelating ligand (i.e., l-histidine amino acid) was covalently attached on the poly(HEMA-GMA) and/or poly(HEMA-GMA)-SA using glutaric dialdehyde as a coupling agent, poly(HEMA-GMA)-H and poly(HEMA-GMA)-SAH membranes, respectively. Then, Cu(II) and Fe(III) ions were chelated through poly(HEMA-GMA)-SAH membrane. The binding characteristics of human immunoglobulin G (IgG) to IMAC membranes and the selectivity of Cu(II) and Fe(III) ions to the IgG have been investigated from aqueous solution using l-histidine attached membrane (poly(HEMA-GMA)-SAH) as a control system. The experimental data was analyzed using two adsorption kinetic models, the pseudo-first-order and the pseudo-second-order, to determine the best-fit equation for the adsorption of IgG onto l-histidine incorporated and/or different metals ion immobilized affinity membranes. The first-order equation in the affinity membrane systems is the most appropriate equation to predict the adsorption capacity for all the tested adsorbents. Moreover, the effect of spacer-arm on the adsorption capacity was evaluated using poly(HEMA-GMA)-H membrane as a control system. The IgG binding order on the affinity membranes was poly(HEMA-GMA)-SAH-Cu(II) > poly(HEMA-GMA)-SAH-Fe(III) > poly(HEMA-GMA)-SAH > poly(HEMA-GMA)-H. Finally, the polarities and the surface free energies of the affinity membranes were determined by contact angle studies.