Electrochemically Triggered Surface Deposition of Polyelectrolytes

An electrochemical approach to surface deposition of polyelectrolytes on self-assembled monolayers is presented. This deposition process can be triggered facilely by a potential bias, which oxidizes ferrocene moieties included in the self-assembled monolayer to ferrocenium, whose charge compensation is fulfilled by polyelectrolytes and associated counterions. This approach is quite general, affording quantitative deposition of both polyanions and polycations with a wide range of chemical identities (synthetic polymers, peptides, and DNA) and molecular weights (10³-10⁷ Da as tested). Conventional layer-by-layer polyelectrolyte deposition can be straightforwardly combined with this method to produce electroactive polymer films. Several techniques, including voltammetry, fluorescence spectroscopy, contact angle analysis, electrochemical quartz crystal microbalance, and atomic force microscopy, were employed to characterize the deposition processes. A detailed discussion on the involved deposition mechanisms is also presented.