Dual-filler mixed matrix membrane with covalent-organic framework and nano TiO2/polyether sulfone for efficient antibody purification

With the rapid expansion of antibody drug market, most biopharmaceutical industries urgently need to optimize their downstream purification processes to reduce production costs and improve market competitiveness. In this study, a dual-filler polyether sulfone (PES) mixed matrix membrane (MMM) that combines covalent-organic framework (COF) with nano TiO₂ was developed to overcome the drawbacks of conventional protein A based purification methods. Firstly, COF@TiO₂ dual-filler was prepared by Schiff base reaction. The proposed dual-filler MMM was fabricated via nonsolvent-induced phase separation (NIPS), followed by functionalization with a Fab-specific affinity peptide (m-EDPW) of trastuzumab through atom-transfer radical-polymerization method. The resulting m-EDPW@COF@TiO₂/PES affinity membrane effectively integrates the merits of COF and TiO₂ and show synergistic effects, demonstrating satisfactory hydrophilicity, anti-fouling ability (BSA rejection rate: 97.7%), enrichment recovery (90.8%), binding capacity for trastuzumab (386.6 mg/g), and long-term stability (∼ 21 days). Particularly, this affinity membrane showed good selectivity and specificity, enabling the successful purification of trastuzumab from spiked HCC1937 cancer cell culture medium with satisfactory purity (∼97.4%) and preservation of the antibody secondary structure. This study not only developed a novel affinity membrane with satisfactory antibody separation performance but also opened a new route for developing dual-filler or multi-filler MMM for highly efficient downstream protein purification.