Electrodepositing DNA Self-Assembled Monolayers on Au: detailing the influence of electrical potential perturbation and surface crystallography.

The preparation of DNA self-assembled monolayers (SAMs) on single crystal gold bead electrodes using an applied potential is evaluated with in-situ electrochemical fluorescence microscopy. Applying a constant deposition potential or a square-wave potential perturbation during the formation of DNA SAMs is compared for two different modification methods: DNA SAM formation on a clean gold surface followed by alkythiol backfilling (as is typically done in literature) or via thiol-exchange on an alkylthiol modified gold surface. DNA SAMs prepared from a chloride containing deposition buffer were not significantly different when using either square-wave potential perturbation or at a constant applied potential even when considering different surface crystallographies. Greater variations were observed when applying more positive potentials for both DNA thiol-exchange and DNA adsorption on clean Au. Our results suggest that using either a constant potential or a square wave potential perturbation for 5 min both create defects by weakening the gold-thiol bond. When the deposition is performed with the adsorption of chloride ions from the electrolyte, the electrodeposition results in a similar increase in DNA coverage when compared to depositions performed at open circuit potentials.