The architecture of responsive polymeric ligands on protein binding and recoveryElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ra01499f

Ligand design and optimization are critical for protein purification during downstream processing. Here the effects of three dimensional architecture of salt- and thermo-responsive polymeric ligands on binding and recovery of bovine serum albumin (BSA) were investigated. The comb-like salt-responsive copolymers consisting of hydrophilic backbone (poly(hydroxylethyl methacrylate) (poly(HEMA))) and branched responsive (poly( N -vinylcaprolactam) (PVCL)) chains have been successfully grafted on membrane substrates as hydrophobic interaction ligands for protein capture and recovery. Protein binding capacity, binding kinetics and recovery were systematically investigated as a function of backbone chain density and chain length. Atom-transfer radical polymerization (ATRP) was used to control the polymer chain length and chain density of grafted brushes. Our results show that the architecture of these polymeric ligands has a significant impact on protein binding and recovery. The protein binding isotherm was found to follow the Freundlich model suggesting a multi-layer adsorption mechanism. Ligand design and optimization are critical for protein purification during downstream processing.