The Energetics of Electron Transfer in Redox-DNA Layers Mimics That of Redox Proteins.

Redox-DNA layers have recently shown unique properties, such as tunable reorganization energy of electron transfer that can be modulated by DNA length or hybridization state and completely suppressed under nanoconfinement. These discoveries, attributed to the changes in the solvation of the redox marker and/or fast chain dynamics, provide a unique opportunity to use electrochemical measurements as a tool to address open questions in ion solvation. Moreover, they offer a pathway to clarify the origin of the largely unsolved problem of establishing low activation barriers for biological electron transfer. Here, high-scan-rate, variable-temperature cyclic voltammetry analyzed using the Marcus formalism and molecular dynamics simulations, reveals that the total free energy barrier of electron transfer consists of two additive elements: the reorganization energy of the partially desolvated redox marker and the energy cost for solvation changes of the redox marker at the solid/liquid interface. These results may have profound implications for our understanding of electron transfer and solvation effects in redox proteins, providing opportunities for better design of artificial photosynthetic systems, biosensing, and energy conversion devices.