Electronic Switch Crafted From DNA

Because double-stranded DNA can conduct electrical charge, it holds promise as a nanoscale component in electronic devices. Dipankar Sen and Yu Chuan Huang of Simon Fraser University, in Burnaby, British Columbia, have evolved that concept by creating the first easily reversible electronic switch made from DNA (J. Am. Chem. Soc., DOI: 10.1021/ja908508j). The double helix they used contains two short stretches of mismatched guanine-guanine base pairs. When the DNA is in an extended conformation in solution, the guanine base pair segments act as an insulator, preventing the DNA from conducting electricity. Adding potassium ions to the solution causes the DNA to contract, pinching closed a loop containing the nonconducting section and allowing current to pass through the remainder of the DNA. The switch can be turned off by sequestering the potassium ions with crown ethers, which allows the DNA to stretch back out. The researchers believe a similar switch could be designed to respond to an electronic signal.