Quantum transport anomalies in DNA containing mispairs

TL;DR

This study investigates how mispairs affect charge transport in DNA sequences, revealing that mispairs can both enhance or reduce current depending on bias and transport mechanisms, with implications for DNA-based electronics.

Contribution

The paper introduces a detailed tight-binding model with parameters from ab initio calculations to analyze mispair effects on DNA charge transport.

Findings

Current decays exponentially with the number of (TA) basepairs at low bias.

High bias can establish multichannel transport, reducing current.

Mispairs near the middle can significantly alter charge transport, either enhancing or decreasing current.

Abstract

The effect of mispair on charge transport in a DNA of sequence (GC)(TA)_N(GC)_3 connected to platinum electrodes is studied using the tight-binding model. With parameters derived from ab initio density functional result, we calculate the current versus bias voltage for DNA with and without mispair and for different numbers of (TA) basepairs N between the single and triple (GC) basepairs. The current decays exponentially with $N$ under low bias but reaches a minimum under high bias when a multichannel transport mechanism is established. A (GA) mispair substituting a (TA) basepair near the middle of the (TA)_N sequence usually enhances the current by one order due to its low ionization energy but may decrease the current significantly when an established multichannel mechanism is broken.