A Prototype Electrochemical Chromatographic Column for Use with Proteins

We developed electrochemical hardware and media targeted for protein chromatography. Two types of stationary phases were investigated. The first comprised gold-plated stainless 316L beads coated with a self-assembled monolayer of 6-mercaptohexan-1-ol and was expected to behave like an ion-exchange resin in the presence of an electric field. The second stationary phase comprised the first stationary phase with further functionalization with immobilized heme moieties and was expected to behave like an immobilized metal affinity resin. We tested the apparatus with both stationary phases using ribonuclease A as a model protein and applied potentials from −0.3 to +0.3 V versus the saturated calomel electrode. Despite low binding capacities, we demonstrated that protein retention on both stationary phases could be controlled with an applied potential. The greatest extent of electromodulation was achieved with the mercaptohexanol-based ion-exchange media.