Peptide-crosslinked IgG-imprinted polymers for antibody capture and separation

Downstream separation and purification of monoclonal antibodies (mAbs) has long been the major bottleneck for their production. Here novel molecularly imprinted polymers (MIPs) of immunoglobulin G (IgG) were designed for their capture and separation from cell culture supernatant. To overcome the severe problems faced by protein-imprinted polymers, i.e., difficult template removal and low imprinting efficiency, a poly(L-glutamic acid) (PLGA)-based peptide crosslinker, instead of commonly used crosslinkers, was employed. In addition, a thiophilic functional monomer, 2-((2-hydroxy-3-(methacryloyloxy)propyl)thio)nicotinic acid (GMA-NA), which can bind with IgG selectively, was designed and used for the synthesis of IgG-imprinted polymers. Because of the reversible and precise pH-induced helix-coil transition of the PLGA segments in the polymers and also the selective binding of GMA-NA with IgG, complete removal of the template protein was achieved under mild conditions. Meanwhile excellent imprinting efficiency was obtained. For the IgG-imprinted polymer with an optimized composition, a high adsorption capacity (790.2 mg/g) and a high IF (5.2) were achieved, both of which are much higher than the previously reported IgG-imprinted polymers. The polymer exhibits high selectivity towards the template IgG against non-template proteins. It also exhibits excellent reusability. The high adsorption capacity, high selectivity and mild elution conditions of the new IgG-imprinted polymer make it good adsorbent for antibody separation. Using the new MIP, IgG was successfully separated from human serum. More importantly, HLA-DRA mAb was successfully separated from cell culture supernatant with a removal rate of 89% and a purity of 87%, confirming the potential of the new MIP in mAb separation.