Evaluation of magnetic particles modified with a hydrophobic charge-induction ligand for antibody capture.

Magnetic particles modified with 5-amino-benzimidazole (ABI), a ligand for hydrophobic charge-induction chromatography, were prepared and used for antibody capture. In this study, with IgG as the model target, and bovine serum albumin (BSA) as the model impurity, the separation mechanism and process of IgG was investigated. The adsorption isotherms of IgG and BSA were measured, and the effects of pH were investigated in the range of pH 4.0-8.0. The maximum adsorption capacity of IgG on the particles was 180mg/ml at pH 7.0, while low adsorption capacity of BSA (64mg/ml) was found at pH 7.0, resulting in good selectivity. The protein-ligand interactions were elucidated by adding NaCl and glycerol. The results indicated the hydrophobic interactions were the main forces for IgG-ligand association. Moreover, the batch uptake and desorption experiments demonstrated the fast adsorption and desorption processes for IgG separation. The purity of IgG separated from mimetic serum could reach 98.6%, and the purity of monoclonal antibody (mAb) from a cell culture supernatant was 97.1%. Magnetic particles with hydrophobic charge-induction ligands showed a robust performance and could purify antibody directly from the complicated feedstock without clarification, which would improve the efficiency of antibody purification.