Multifunctionalization of RC membrane via combining surface initiated RAFT polymerization with thiolactone chemistry for enhanced antibody recovery

Hydrophobic charge induction chromatography (HCIC) is becoming an attractive separation technology for antibody purification but suffers from low recovery. Herein we attempted to incorporate temperature responsiveness and strong ion exchange functions onto HCIC membrane adsorber to enhance antibody recovery. We proposed a multifunctional surface modification method combining surface-initiated reversible addition-fracture chain transfer polymerization (SI-RAFT) and the thiolactone chemistry . A regenerated cellulose (RC) membrane was modified by the SI-RAFT of N-isopropylacrylamide (NIPAAm) and thiolactone acrylamide (TIaAm), followed by the “amine-thiol-ene” cascade reaction of thiolactone with tryptamine , a HCIC ligand and methylpropylene trioxyethyl ammonium chloride (METAC), a strong ion exchanger. Temperature, pH and salt effects on IgG and BSA adsorption were investigated. After optimization, the RC-HCIC membrane adsorber had a static adsorption capacity of 41 mg/g for IgG, and an ideal IgG to BSA separation factor of 4.7, under the condition of pH = 7 and T  = 30 °C. The membrane showed temperature-responsive IgG uptake from 10 °C to 35 °C. At pH = 5 and T = 10 °C, the recovery of IgG reached 93.5%, and the activity was well retained. These results indicate that the combination of temperature responsiveness of NIPAAm with HCIC is an effective strategy to improve the IgG recovery.