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

Redox-DNA layers have recently demonstrated unique properties, such as reorganization energy of electron transfer that can be tuned with DNA length or hybridization, and completely suppressed under nanoconfinement. These dis-coveries, 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 and to clarify the origin of low reorganization energies reported in protein 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 fast-moving molecules, providing opportunities for better design of artificial photosynthetic systems, biosensing, and ener-gy conversion devices.