Facile and green fabrication of cation exchange membrane adsorber with unprecedented adsorption capacity for protein purification

- A novel membrane adsorber is prepared by grafting alginate dialdehyde on nylon membrane.
- Alginate dialdehyde (ADA) reacts with sodium bisulfite to generate sulphonic groups on ligands.
- Sulphonic and carboxylic groups (both on membrane and ADA) endow a high binding capacity.
- The novel membrane adsorber captures lysozyme from chicken egg white solution.
- The purified lysozyme shows similar specific activity as commercial product.

Fabricating membrane adsorbers with high adsorption capacity and appreciable throughput for the separation and purification of protein products is challenging in biomedical and pharmaceutical industries. Herein, we report the synthesis of a novel membrane adsorber by functionalizing a nylon microfiltration membrane with alginate dialdehyde (ADA) followed by sulphonic addition, without any solvent usage, and its successful application in the purification of lysozyme. Taking advantage of abundant dual cation exchange (CEX) groups on sulphonic-ADA (S-ADA) ligands, this novel S-ADA-nylon membrane adsorber showed an unprecedented static binding capicity of 286 mg/mL for lysozyme adsorption. Meanwhile, the prepared membrane adsorber could be easily regenerated (complete protein elution) under mild conditions and be reused at least for five times. Featured with a unique selectivity, the S-ADA-nylon membrane also captured lysozyme from chicken egg white solution with a high purity (100%) and a high recovery of 98%. The purified lysozyme showed similar specific activity as commercial product. The present work provides a facile, green and low-cost approach for the preparation of high-performance membrane adsorbers, which has a great potential in protein production.