Electric detection of DNA hybridization by nanoparticle nanoswitch

Abstract

Abstract DNA hybridization was electrically detected by monitoring the electric conductance change of a nanodevice comprised of two electrodes separated by a narrow gap whose width was comparable to the size of a nanoparticle. Specific hybridization of a target DNA to the capture DNA on the electrode and the probe DNA on the gold nanoparticle resulted in the immobilization of gold nanoparticles between the electrodes, which in turn led to a conductance jump across the gap. After fabrication of the device, the whole area except the gap region was passivated by e-beam resist to reduce a possible loss of target DNA. Two types of thiol-modified single-strand DNAs, which would specifically hybridize with portions of the target DNA, were covalently attached onto the surfaces of the gold electrodes and nanoparticles. The conductance change upon immobilization of the nanoparticle was readily measurable at room temperature. The nanoparticles immobilized between the electrodes can be removed by a simple heat treatment.