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

## TL;DR

A new fabrication method for block copolymer membranes is introduced, offering better performance and efficiency in bioprocessing.

## Contribution

A direct spin-coating method for BCP membranes is proposed, simplifying fabrication and improving filtration performance.

## Key findings

- PS-b-PMMA membranes showed comparable transmission rates to PES membranes for proteins.
- The new membranes achieved a ninefold improvement in thyroglobulin rejection.
- The method reduces the need for complex optimization and chromatographic steps in biopharmaceuticals.

## Abstract

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)-block-poly(methyl methacrylate) (PS-b-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-b-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.