The architecture of responsive polymeric ligands on protein binding and recovery

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.