Abstract: There is disclosed a relatively simple method to increase the performance of surface localised multi-valent affinity ligands whose target's isoelectric pH differs significantly from the ligand's optimal target-binding pH. This situation can result in ligand binding of target affecting local pH and subsequent binding of more target. Increasing the buffering capacity of the ligand via recombinant or other addition of charge groups to the ligand is expected to partially offset such effects, leading to enhanced binding capacity as well as possible secondary favourable alterations in regard to ligand elution pH, and non-specific surface binding of non-target proteins.