Redox Interfaces for Electrochemically Controlled Protein–Surface Interactions: Bioseparations and Heterogeneous Enzyme Catalysis

Redox-active materials are an attractive platform for engineering specific interactions with charged species by electrochemical control. We present nanostructured redox-electrodes, functionalized with poly(vinyl)ferrocene embedded in a carbon nanotube matrix, for modulating the adsorption and release of proteins through electrochemical potential swings. The affinity of the interface toward proteins increased dramatically following oxidation of the ferrocenes, and, due to the Faradaic nature of the organometallic centers, the electrodes were maintained at sufficiently low overpotentials to ensure the preservation of both protein structure and catalytic activity. Our system was selective for various proteins based on size and charge distribution, and exhibited fast kinetics ( 200 mg/g) under moderate overpotentials (+0.4 V vs Ag/AgCl), as well as remarkable stability for binding under ferrocene oxidation conditions. The preservation of bioacti...