One-Electron Oxidation Potentials and Hole Delocalization in Heterogeneous Single-Stranded DNA

Area of Science:

• Computational chemistry
• Molecular biophysics
• Nanotechnology

Background:

• Understanding DNA charge transfer is crucial for applications like DNA nanowires and electrochemical biosensors.
• Investigating redox properties and charge transport mechanisms in DNA is essential for advancing these technologies.

Purpose of the Study:

• To computationally explore the one-electron oxidation potential and hole delocalization in heterogeneous single-stranded DNA.
• To elucidate the charge transport mechanisms (hopping vs. tunneling) in DNA based on sequence and structural factors.

Main Methods:

• A two-step computational protocol combining quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations with QM1/QM2/continuum and Marcus theory.
• Analysis of conformational space sampling and energetic properties over selected geometries.

Main Results:

• The one-electron oxidation potential of heterogeneous DNA strands can be predicted as a linear combination of homogeneous strands.
• Hole delocalization between nucleobases is generally small, supporting a hopping charge transport mechanism.
• Charge delocalization increases when nucleobases have similar reducing powers, enhancing tunneling contributions.

Conclusions:

• The sequence of nucleotides, rather than internal strand structure, predominantly dictates hole delocalization in DNA.
• Hopping is the primary charge transport mechanism, but tunneling becomes significant under specific electronic conditions.
• Computational modeling provides key insights into DNA charge transport for biosensor and nanowire development.