A Versatile Fabrication Route for Screening of Block Copolymer Membranes in Bioprocessing

Traditional poly(ether sulfone) (PES) filters, widely used for sterile, viral, and ultrafiltration, often exhibit restrictions in their selectivity-permeability profile due to their heterogeneous pore size distribution. This limitation has sparked interest in developing novel isoporous membrane materials and fabrication techniques. Among promising candidates, block copolymer (BCP) membranes produced via self-assembly and nonsolvent-induced phase separation (SNIPS) offer significant advantages, including tunable pore size, narrow pore size distribution, high porosity, and enhanced mechanical flexibility. However, optimizing the structure formation in SNIPS remains a complex and time-consuming process, making it unsuitable for rapidly screening new BCP candidates. In response, this study introduces an alternative fabrication approach based on the direct spin-coating of BCPs onto anodic aluminum oxide (AAO) supports. Using this method, a poly(styrene)-<i>block</i>-poly(methyl methacrylate) (PS-<i>b</i>-PMMA) thin film was directly cast onto a water-filled AAO support, enabling the formation of an isoporous membrane structure for filtration applications, significantly reducing the complexity of structure-application optimization. When compared to commercial PES membranes with similar molecular weight cut-offs, these novel PS-<i>b</i>-PMMA thin-film composite membranes exhibited comparable transmission rates for bovine serum albumin and a monoclonal antibody, while delivering a ninefold improvement for thyroglobulin rejection. This superior cutoff precession highlights their potential to remove viruses and antibody aggregates during the downstream processing of monoclonal antibody production. By reducing the burden of chromatographic polishing steps, this advance offers promise for enhancing efficiency and lowering costs in biopharmaceutical manufacturing.