Protein A-connected SMA-modified PVDF membranes for high-selectivity IgG capture

The present research relates to a method for preparing high-performance polymeric membranes for protein purification. The membrane matrix is made of polyvinylidene fluoride or polyvinylidene difluoride (PVDF) and styrene maleic anhydride (SMAn) and fabricated using an improved phase inversion method. The PVDF serves as the support skeleton of the membrane and the RAFT (Reversible addition-fragmentation chain transfer) polymerized SMAn copolymer serves as the active component. By optimizing the ratios of Styrene: Maleic anhydride in SMAn copolymer, superior membrane properties can be fabricated with high porosity and surface-to-volume ratio for maximum protein binding throughput. The PVDF-SMAn membrane matrix can be tailored with suitable chemistries for the functionalization of the ligands of interest. In particular, a mixed-mode membrane and an affinity-based membrane have been fabricated immobilizing tris(hydroxymethyl)aminomethane (Tris) and protein A onto the membrane matrix via the SMAn copolymer, respectively. The morphology of the fabricated membrane matrix, as revealed by electron microscopy, shows superior porosity and surface area which are important for achieving a high protein binding capacity membrane. The maximum DBC for IgG observed under flow conditions, via bind-and-elute mode, using pure IgG sample as the feed solution was about 400 mg and 85 mg per ml for the mixed-mode and protein A membrane, respectively. The present research provides an efficient and simple method for fabricating high-performance polymeric membranes with optimum ligand distribution and internal structure for downstream purification of biologics.