Efficient isolation of immunoglobulin G by paramagnetic polymer beads modified with 2-mercapto-4-mythyl-pyrimidine

A potential non-chromatographic technique was explored to purify antibody from human serum based on the thiophilic magnetic beads, which were prepared with vinyl acetate and divinylbenzene by microsuspension polymerization. Depending on the effective surface modification of 2-mercapto-4-mythyl-pyrimidine and divinyl-sulfone, the micron-size magnetic beads could selectively capture immunoglobulin G (IgG) from human serum in a non salt-dependent manner. Just because this specific adsorption towards IgG could be carried out in the physiological pH range (5-7) and at low salt concentration (25 mM PBS aqueous solution), the isolated antibody could keep a high purity (92.7%) and strong bioactivity (99%). However, the responding recovery of bound antibodies from magnetic beads was greatly influenced by the types of salt in the eluate. The sodium chloride aqueous solution was much effective to release IgG from these magnetic beads. Because the driving force for this selective recognition was attributed to electron donor-acceptor (EDA) interaction, the effect of temperature on the adsorption was not obvious. Using the successive isolation, the yield of this technology even reached 79.4%. The strong specificity, rapid process, mild conditions and excellent reusability of this technique bring it great potentialities into the antibodies purification on a large scale.