Evaluating antibody monomer separation from associated aggregates using mixed-mode chromatography

Aggregate level is a key factor when assessing quality attributes of antibody product, since the aggregation might impact the biological activity of biopharmaceutical. Effective separation methods are usually essential in manufacturing processes. In this study, three mixed-mode resins, i.e. Capto adhere and two home-made resins with benzylamine and butylamine as the functional ligands (named BA and AB), were used to investigate the separation performances of antibody aggregate removal processes. In addition, two traditional resins (Q Sepharose FF and Phenyl Sepharose 6 FF) were also investigated to explore the role of molecular interaction in the aggregate removal. The results indicated that the removal efficiency was highly dependent on the mass loading. With the sample load of 50 mg/ml resin both Capto adhere and BA resins can significantly reduce the aggregate level from 20.5% to 2.6% and 2.4%, respectively, while a relatively low degree of aggregate reduction was found with the traditional resins. The research indicates that both hydrophobic interaction and electrostatic interaction are critical for the aggregate removal and the cooperativity of different molecular interactions is important for the effective aggregates removal with mixed-mode resins.