Researchers Create DNA Walker for Biocomputational Devices

From Medgadget:

The fact that DNA molecules can potentially be used as nanowires and nanotransistors in DNA-based computers has already been profiled on our pages before. Now a group from Caltech has synthesized a molecular structure, designed from single and double-stranded pieces of DNA, that functions as a "molecular walker," that can be employed in dynamic molecular computational devices for therapeutic, diagnostic, and other applications. Researchers at the California Institute of Technology report they are able to program the pathways by which DNA molecules self-assemble, and hence to engineer diverse dynamic functions at the molecular level. "This capability is essential for something like the memory of a DNA computer, which would need large groups of molecules that can toggle from the on/off position in a fast and reliable fashion," said National Science Foundation (NSF) Program Manager Kathy Covert. Researchers Peng Yin, Harry Choi, Colby Calvert and Niles Pierce, who are funded by NSF, report their research results in the Jan. 17 issue of Nature. To illustrate their approach for encoding self-assembly and disassembly pathways into DNA sequences, the researchers experimentally demonstrated the locomotion of a two-legged DNA walker that moves along a DNA track without human intervention... The walker places foot-over-foot as each appendage is attracted biochemically to the next hairpin along the track. As foot and hairpin make contact, the hairpin unravels. The free end of the hairpin then catches a complementary hairpin that is free-floating in the solution that the whole system is immersed in. Both hairpins coil together forming a "waste duplex" (or the familiarly shaped double helix), releasing the walker's foot for its next stride. If the walker reaches the end of the track successfully, it leaves behind non-reusable material, and the track is spent. Its travels are more perilous than may seem if it lifts the wrong foot and finds itself trapped between two open hairpins, the walker will fall off never seeing the end of its track.

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