US chemists have designed the world’s first two-footed molecular robot and taken it for a stroll in a lab dish, the British weekly New Scientist says in its next issue, out on Saturday. The robot’s legs, which measure just 10 billionths of a metre, are the first nanoscale device to be capable of bipedal movement. The robot is able to “walk” because it is made out of scraps of DNA, the molecule of life, which comprises a dual strand joined together by mating pairs of chemical rungs, called bases. A single strand of DNA, like one side of a zip fastener, provides the track along which the robot moves. The robot itself looks rather like a geometry compass, with two legs comprising 36 DNA bases. It gets attached to the walkway thanks to tiny anchor strands of DNA that are introduced into the solution and which bind to the track as well as the undersides of the feet. To get the robot to move forward, another piece of DNA, called an unset strand, is introduced. It peels the anchor strand away from the track. This causes the foot to move forward and look for the next mating anchor strand along the line. Repeating the procedure with the backward foot gets the robot to shuffle along. The biped’s inventors are Nadrian Seeman and William Sherman of New York University, who have published their work in a peer-reviewed journal, Nano Letters.
