(219e) Insights on Ligand-Protein Interactions in Affinity Membranes for Antibody Purification
Preliminary experiments with commercial cellulosic membranes decorated with these ligands, in particular with one of them called HPTA, showed promising properties in terms of binding capacity, selectivity and overall recovery of IgG from complex mixtures. Indeed, there are several issues related to residual non-specific binding and to the antibody recovery with the elution step, that appear to be associated to the membrane surface and to the spacer arm and not to the ligand itself. This was demonstrated in fundamental studies in which the influence of the endcapping protocol and of the spacer arm on the new ligand selectivity was studied, using pure solutions of IgG, BSA and lysozyme, as well as mixtures of IgG and BSA and lysozyme.
Current work is focused on the modification of the properties of the membrane surface in proximity of the affinity ligand by functionalizing part of the surface with histidines or similar residues containing amines, that able to change their protonation state as a function of pH. A modification of the charge of the surface is indeed expected to change drastically the energy of interaction of the adsorbed antibody with the surface, thus improving selectivity.