Vik points to an article in Technology Research News ("Morphing DNA makes motor", by Kimberly Patch, 16 January 2002) on the research by Nadrian Seeman at New York University into DNA-based devices:
"Dr. Nadrian Seeman has created and tested a 4-step DNA motor that can rotate indefinitely. Fuelled by other DNA strands, the molecular motor described in [the] TRN article operates in controllable steps. Dr. Seeman says that the range of motion is from 0.04 to 4 nm, although movement of 35nm has been made using arrays of the devices."
This item was also reported here on 2 January 2002.