Saturday, April 23, 2005

Smaller smallest nanobats walking

New Scientist Breaking News - DNA robot takes its first steps
Jenny Hogan, Boston

A microscopic biped with legs just 10 nanometres long and fashioned from fragments of DNA has taken its first steps.

The nanowalker is being hailed as a major breakthrough by nanotechnologists. The biped's inventors, chemists Nadrian Seeman and William Sherman of New York University, say that while many scientists have been trying to build nanoscale devices capable of bipedal motion, theirs is the first to succeed.

"It's an advance on everything that has gone before," says Bernard Yurke of Bell Labs in New Jersey, part of the team that made one of the best-known molecular machines to date: a pair of "tweezers" also constructed from DNA strands (New Scientist print edition, 12 August 2000). Like similar molecular-scale efforts, the tweezers' arms merely open and close: they can not move around.

But for nanoscale manufacturing to become a realistic prospect, mobile microscopic robots will be needed to assemble other nanomachines and move useful molecules and atoms around.

Pairing up

The New York team's biped can "walk" because its DNA-based legs are able to detach themselves from a DNA-based track, move along a bit, then reattach themselves.

Why DNA? Two reasons. First, unlike other polymers, DNA chains like to pair up. However, two DNA strands will only "zip" together if the sequences of bases in each strand complement each other in the right way - so by tweaking the sequences chemists get a high degree of control over where each strand attaches. Second, researchers hope that cells can one day be engineered to manufacture these DNA-based machines.

walking DNA nanobot

The walker takes its nanostroll in a bath of a liquid called a "nondenaturing buffer", which stops the DNA falling apart. To start with, millions of walkers and tracks are floating around freely in this liquid. Only when the researchers add the DNA anchors do the bipeds' feet fix onto the footpaths. Then the unset strands can be added to begin the walking process.

The researchers were able to confirm that the nanowalkers had taken their first steps by taking small samples of the solution after each DNA addition. By feeding the material through a gel which separates DNA molecules by size and shape, they confirmed where the feet were attached - it is the same technique that gives "DNA fingerprints" in forensics.

Persuading the walker to ferry a load, such as a metal atom, is the team's next challenge.

Journal reference: Nano Letters (DOI: 10.1021/n1049527q)

New Scientist Breaking News - DNA robot takes its first steps


Post a Comment

Subscribe to Post Comments [Atom]

<< Home