Charge Transfer Mechanism in Guanine-based Self-Assembled Monolayers on a Gold Surface

In this work, we have theoretically determined the one-electron oxidation potentials and charge transfer mechanisms in complex systems based on a self-assembled monolayer of guanine molecules adsorbed on a gold surface through different organic linkers. Simulations were carried out in the framework of the Marcus theory and in combination with an additive scheme previously developed. The conformational sampling, description of the environment and effects caused by the linker have been considered. We unravel the phenomena of electric current transport by evaluating the different stages in which charge transfer could occur. The results revealed that the positive charge migrates from the organic layer to the gold surface through a single ligand and driven with the help of the electrostatic interactions of the surrounding molecules. The established computational protocol sheds light on the mechanism behind charge transport in electrochemical DNA-based biosensor nanodevices.