Charge transport in a multi-terminal DNA tetrahedron: Interplay among contact position, disorder, and base-pair mismatch

TL;DR

This study investigates how contact position, disorder, and mismatches affect charge transport in DNA tetrahedra, revealing regimes of efficiency and potential for spin filtering, with implications for nanodevice design.

Contribution

It provides a comprehensive analysis of charge transport behavior in multi-terminal DNA tetrahedra considering various factors, highlighting new regimes and spin filtering capabilities.

Findings

Charge transport efficiency is nearly independent of contact position in weak disorder.

Single base-pair mismatch dramatically reduces charge transport, aligning with experiments.

DNA tetrahedron can act as an efficient spin filter, separating spin-polarized electrons.

Abstract

As a secondary structure of DNA, DNA tetrahedra exhibit intriguing charge transport phenomena and provide a promising platform for wide applications like biosensors, as shown in recent electrochemical experiments. Here, we study charge transport in a multi-terminal DNA tetrahedron, finding that its charge transport properties strongly depend upon the interplay among contact position, on-site energy disorder, and base-pair mismatch. Our results indicate that the charge transport efficiency is nearly independent of contact position in the weak disorder regime, and is dramatically declined by the occurrence of a single base-pair mismatch between the source and the drain, in accordance with experimental results [J. Am. Chem. Soc. {\bf 134}, 13148 (2012); Chem. Sci. {\bf 9}, 979 (2018)]. By contrast, the charge transport efficiency could be enhanced monotonically by shifting the source toward the drain in the strong disorder regime, and be increased when the base-pair mismatch takes place exactly at the contact position. In particular, when the source moves successively from the top vertex to the drain, the charge transport through the tetrahedral DNA device can be separated into three regimes, ranging from disorder-induced linear decrement of charge transport to disorder-insensitive charge transport, and to disorder-enhanced charge transport. Finally, we predict that the DNA tetrahedron functions as a more efficient spin filter compared to double-stranded DNA and opposite spin polarization could be observed at different drains, which may be used to separate spin-unpolarized electrons into spin-up ones and spin-down ones. These results could be readily checked by electrochemical measurements and may help for designing novel DNA tetrahedron-based molecular nanodevices.