(449bj) Developing High Performance Responsive HIC Membrane Adsorbers

Authors: 
Qian, X., University of Arkansas
Liu, Z., University of Arkansas
Wickramasinghe, R., University of Arkansas

Fast convective mass transport, low pressure drop and better accessibility to large biomolecules make membrane adsorbers an attractive alternative to packed-bed chromatography used in the downstream process. Responsive hydrophobic interaction chromatography (HIC) membranes are investigated for protein purification in a bind/elute mode. The surface of these responsive HIC is grafted with polymeric ligands with tunable hydrophobicity. Unlike traditional HIC ligands, responsive HIC ligands can switch between hydrophobic state (under high salt) and hydrophilic state (under low salt) for protein binding and elution respectively reducing the possibility of irreversible binding.

Thermo-responsive poly (N-vinyl caprolactam) (PVCL) ligands have been grafted on the surface of regenerated cellulose membrane (0.45 µm pore size) via atom transfer radical polymerization (ATRP). The conformations and degrees of hydration/dehydration of these responsive ligands are concentration and salt specific. Systematic studies have been performed to understand and optimize the chromatographic behavior of these responsive HIC membranes using BSA and IgG as model proteins. In addition, the effects of copolymerization with other monomers such as hydroxyethyl methacrylate, N-(2-hydroxypropyl) methacrylamide and hydroxyethyl acrylamide on binding capacity and recovery were also investigated. Our results suggest that the 3-D conformation, monomer property and composition all strongly affect the binding capacity and recovery.