Sequence specific electronic conduction through polyion-stabilized double-stranded DNA in nanoscale break junctions

Authors

Ajit K. Mahapatro, Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue UniversityFollow
Kyung J. Jeong, Birck Nanotechnology Center, Departments of Chemical and Biomedical Engineering, Purdue UniversityFollow
Gil U. Lee, Birck Nanotechnology Center, Departments of Chemical and Biomedical Engineering, Purdue UniversityFollow
David B. Janes, Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue UniversityFollow

Abstract

This paper presents a study of sequence specific electronic conduction through short (15-base- pair) double-stranded (ds) DNA molecules, measured by immobilizing 3'-thiol-derivatized DNAs in nanometre scale gaps between gold electrodes. The polycation spermidine was used to stabilize the ds-DNA structure, allowing electrical measurements to be performed in a dry state. For specific sequences, the conductivity was observed to scale with the surface density of immobilized DNA, which can be controlled by the buffer concentration. A series of 15-base DNA oligonucleotide pairs, in which the centre sequence of five base pairs was changed from G: C to A: T pairs, has been studied. The conductivity per molecule is observed to decrease exponentially with the number of adjacent A: T pairs replacing G: C pairs, consistent with a barrier at the A: T sites. Conductance-based devices for short DNA sequences could provide sensing approaches with direct electrical readout, as well as label-free detection.

Date of this Version

May 2007