Science 324, 67–71 (2009)

Researchers have designed a DNA molecule that can 'walk' for two-and-a-half steps in a predetermined direction along a DNA track.

Nadrian Seeman at New York University and his colleagues created a 49-nanometre-long track of bound DNA strands with loops, and a single-stranded DNA 'walker' molecule. The walker ratchets itself along when its front 'leg' binds to the next loop on the track, triggering a reaction that frees the back leg. Chemical analyses showed the walker took a step 74% of the time.

The team is exploring other chemical reactions besides base-pair binding to drive the walkers. If such constructs can be designed to carry cargo, they could be used to build molecular complexes, the researchers say.