Two spiders are walking along a track – a seemingly ordinary scene, but these are no ordinary spiders. They are molecular robots and they, like the tracks they stride over, are fashioned from DNA. One of them has four legs and marches over its DNA landscape, turning and stopping with no controls from its human creators. The other has four legs and three arms – it walks along a miniature assembly line, picking up three pieces of cargo from loading machines (also made of DNA) and attaching them to itself. All of this is happening at the nanometre scale, far beyond what the naked eye can discern. Welcome to the exciting future of nanotechnology.
The two robots are the stars of two new papers that describe the latest advances in making independent, programmable nano-scale robots out of individual molecules. Such creations have featured in science-fiction stories for decades, from Michael Crichton’s Prey to Red Dwarf, but in reality, there are many barriers to creating such machines. For a start, big robots can be loaded with masses of software that guides their actions – no such luck at the nano-level.
The two new studies have solved this problem by programming the robots’ actions into their environment rather than their bodies. Standing on the shoulders of giants, both studies fuse two of the most interesting advances in nanotechnology: the design of DNA machines, fashioned from life’s essential double helix and possessing the ability to walk about; and the invention of DNA origami, where sets of specially constructed DNA molecules can be fused together into beautiful sheets and sculptures. Combine the two and you get a robot walker and a track for it to walk upon.