Silica resins and peptide ligands to develop disposable affinity adsorbents for antibody purification

Abstract

A study is presented on the use of porous silica resins with tailored properties to develop affinity adsorbents for the purification of immunoglobulin G (IgG). Chromatorex® silica resins were utilized to study the dependence of IgG binding upon functional group density, pore size, and specific surface area. The IgG-binding peptide HWRGWV was chosen to demonstrate the potential of combining inexpensive substrates and ligands into efficient, yet disposable, adsorbents. The static binding capacity (SBC) of silica-peptide adsorbents depends significantly on surface area and pore size, yet minimally on ligand density. Chromatorex®-NH2 MB 800 HC (pore size 800 Å, surface area 31 m2/g) and MB 700 HC (700 Å, 44 m2/g) showed SBC of 55 and 75 mg IgG per mL resin, respectively. The dynamic binding capacity (DBC) reached values of up to 60 mg/mL at 5 min residence time, and was found to be almost independent of flow rate, thus offering a much higher productivity (capacity vs. residence time) than Sepharose resins. A selected adsorbent was utilized for purifying monoclonal antibodies from Chinese hamster ovary (CHO) cell culture supernatants, and polyclonal antibodies from llama and rabbit serum. Under optimized conditions, the silica-peptide adsorbent gave a Mab purity above 90%, 4 log removal of host cell DNA, 1.5 log removal of host cell proteins (HCPs) and Mab recovery of 89% and 92%. Similarly, llama and rabbit IgG were isolated at 80%–85% purity. These results demonstrate that porous silica, a non-traditional substrate for protein purification, shows great promise as potentially single-use affinity adsorbent for protein purification.