Developing an efficient method of protein purification has been one of the challenges in biopharmaceutical industry. The objective of protein purification is to capture the target protein with dynamic adsorption and the least impurities. In this research, multimodal membranes have been developed to test static binding capacity (SBC) of protein. These membranes are functionalized with ligands that exhibit both Columbic interactions and hydrophobic interactions with the protein. Operational conditions are widened compared to the traditional exchange membrane; a high SBC can be achieved in the presence of an ionic buffer.

 The multimodal membranes tested in this research were produced by attaching poly(glycidyl methacrylate) to the regenerated cellulose membrane via atom transfer radical polymerization. With the presence of the reactive epoxy group, a ligand attachment of 4-mercaptobenzoic acid was able to be performed. To evaluate the performance of the membranes, SBC of the protein Immunoglobulin G (IgG) was measured. Study parameters included the buffer pH and ionic solution which have been found to affect both the hydrophobic and Coulombic interactions. In order to test the Columbic and hydrophobic interactions, protein adsorption of IgG was conducted in varying ionic solutions, and SBC was measured.