No abstract

No abstract

This paper describes an electroless gold plating process for particulate 316L stainless steel. The process is based on a mildly acidic gold sodium thiosulfate/ascorbic acid plating solution and is performed under an inert environment at room temperature. The process affords a gold deposition efficiency of ϳ50% as inferred from a modified tin chloride based spectrophotometric assay for gold ion concentration. Successful gold deposition depended on the removal of the thin, passivating surface oxide layer on the stainless steel; this was accomplished by an initial cleaning step with 2 M HCl. In situ cyclic voltammetry experiments on a stainless steel electrode and atomic force microscopy scans on small coupons were used to further characterize the oxide removal and gold deposition reactions.

No abstract

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 secondary stationary phase comprised the first stationary phase with further functionalization with immobilized heme moieties and was expected to behave like immobilized metal affinity resin. We tested 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.