Direct Detection of Nucleic Acids by Tagging Phosphates on Their Backbones with Conductive Nanoparticles

We report here a biosensor for the direct electrical detection of nucleic acids by forming conductive paths with zirconium-activated indium tin oxide (ITO) nanoparticle tags in the gaps of a pair of interdigitated electrodes. The formation of the electrical conductive ITO nanoparticle networks in the gaps bridges the electrode pair, allowing the detection of nucleic acids at subpicomolar levels with high specificity. The nucleic acid biosensor described here is rapid, ultrasensitive, and is able to directly detect nucleic acid without involving a biological ligation, a second probe, or amplification. It is of particular importance to the development of gene expression profiling tools.