Academics Andre's Research Biocuriosities Books Graduate School History of Science Hot off the Press Igor's Research Interdisciplinarity Molecule of the Month Open Access Philip's Research Philosophy of Science Physics Physicsworld.com
Backreaction Ceclia's Blog at PHD Comics Cocktail Party Physics Cosmic Variance The Daily Transcript Easternblot Everyday Scientist The Evilutionary Biologist Freelancing Science The Futile Cycle Good Math, Bad Math iMechanica in singulo Incoherently Scattered Ponderings Juniorprof Klara Stefflova Life of a Lab Rat The Loom Metadatta Mixed States Morning Coffee Physics Not Even Wrong Notes from the biomass Notional Slurry OpenScience Project Pharyngula PLoS Blog Ponderings of a fool Recombinants The Sandwalk SciAm Observations ScienceBlogs Scientific Clearing House Shtetl-Optimized Three-toed Sloth Uncertain Principles What's New by Bob Park
Last month, there was a Nature Nanotechnology article [abstract, full text is toll access] reporting new measurements of DNA conductivity from Jacqueline Barton’s and Colin Nuckolls’ groups.
The team began with a nanotube—a tiny tube of carbon about as thick as DNA itself—that was integrated within a simple electrical circuit. A 6-nm section of the nanotube was removed using plasma ion etching. This procedure not only cuts the tube, but also oxidizes the remaining tips. This makes it possible to bridge the gap with a DNA molecule with ends that have been designed to form strong chemical bonds with the oxidized tips.
This meant that they had a reliable, well defined connection between the bridging DNA molecules and the nanotube electrodes that allowed them to do their measurements in water at room temperature. Since everything is bathed in water they could add a DNA cutting enzyme to show that this breaks the circuit they formed and could also de-hybridze their bridging double strands, leaving only a single strand with a known sequence. Then, by flowing in an almost complementary strand, they could measure the effect of single base mismatches. Even a single mismatch increased the DNA’s resistance by 300 fold.
This structural sensitivity poses a significant challenge to anyone dreaming of making self-assembled circuits directly from DNA, but their system might also make a nice miniaturizable device for detecting single nucleotide polymorphisms, or SNPS. For this to be feasible, one of the first things they would need to improve is the rate at which they get successful DNA bridging. Right now it’s a bit low for commercial applications with their method producing “10 working devices out of 370 that were tested.”
For more, check out my news story at physicsworld.com.
Biocurious is written by Andre Brown and Philip Johnson, since 2005. Content of the weblog is licensed under a Creative Commons Attribution-Share Alike 3.0 License.
