Understanding the electronic properties of single- and double-stranded DNA

Understanding the charge transfer mechanism through deoxyribonucleic acid (DNA) molecules remains a challenge for numerous theoretical and experimental studies in order to be utilized in nanoelectronic devices. Various methods have attempted to investigate the conductivity of double-stranded (ds-) and single-stranded DNA (ssDNA) molecules. However, different electronic behaviors of these molecules are not clearly understood due to the complexity and lack of accuracy of the methods applied in these studies. In this work however, we demonstrated an electronic method to study the electrical behavior of synthetic ssDNA or dsDNA integrated within printed circuit board (PCB)-based metal (gold)-semiconductor (DNA) Schottky junctions. The results obtained in this work are in agreement with other studies reporting dsDNA as having higher conductivity than ssDNA as observed by us in the range of 4-6μA for the former and 2-3μA for the latter at an applied bias of 3V. Selected solid-state parameters such as turn-on voltage, series resistance, shunt resistance, ideality factor, and saturation current were also calculated for the specifically designed ss- and dsDNA sequences using the thermionic emission model. The results also showed that the highest conductance was observed for dsDNA with guanine and cytosine base pairs, while the lowest conductance was for ssDNA with adenine and thymine bases. We believe the results of this preliminary work involving the gold-DNA Schottky junction may allow the interrogation of DNA charge transfer mechanisms and contribute to better understanding its elusive electronic properties

Exploring the Electronic Properties of Ribonucleic Acids Integrated Within a Schottky-Like Junction

Deoxyribonucleic acid (DNA), being the main biomolecule of life, has been studied extensively in terms of its electronic properties, charge transport mechanisms and potential use in nano-electronic devices. The ability of DNA to self-replicate, self-assemble and mediate charge transfer has made it an interesting molecule to multidisciplinary researchers. However, not much attention has been given to ribonucleic acid (RNA), which is an equally important biomolecule that shares some common features with DNA. Elucidation of RNA’s electronic behavior could provide more information regarding its electronic properties, potentially offering a new biomolecule for application in bioelectronics. In this work, RNA samples integrated within two metal electrodes were subjected to positive and negative bias potentials and their resulting current profiles were investigated. Interestingly, current rectification similar to electric field-induced semi-conductive behavior of conventional Schottky junctions was observed for all RNA samples tested, indicating highly characteristic RNA-specific Schottky profiles. A non-linear profile was observed from the current–voltage (I–V) characteristics of gold (Au)-RNA-Au structures showing resemblance to metal-DNA structures investigated previously. Various solid-state parameters such as turn-on voltage, shunt resistance, series resistance and ideality factor were also calculated to further understand the biomaterial’s solid-state behavior. These results successfully demonstrated the exciting observation of the semi-conductive-like behavior of RNA which could be utilized as a tool in molecular electronics. © 2019, The Minerals, Metals & Materials Society