Nanomotor from DNA Strand

Phrogger writes "Nanomotors have been built from multiple DNA strands before this but this is the first to be built from a single strand. Said to be more practical, this holds wonderful promise for treating diseases such as cancer."

Really really small blinking lights

[hij]

They confirmed that it worked by attaching a light-emitting organic molecule to one end and a light-quenching molecule to the other. When the motor extended, separating the quencher and emitter, the light went on. When it curled up, the light went out.

Cool! This would be perfect for the world's smallest redlight district.

eh?

[skilef]

I'm a biologist myself, but the concept of nanomotors eludes me. As I listen to the term 'nanomotor', I think of a new tiny apparatus capable of moving itself (and cargo) to a destination. This is mentioned in the article as well, but hybridization (binding of DNA and a target) and diffusion could do the job as well.. What is that special property of hinging DNA that can improve medicine research/efficiency?

I'll tell you what it's for...

[monkeyserver.com]

To summarise:
These could be used to help drugs better "stick to" cancer cells. They could also help determine which cells are cancerous, helping to reduce some of the horrible side effects seen in such treatments as chemotherapy.
They could also be used for "test-tube manufacturing," think nano-bots :-P
To quote the article:
The first use of DNA motors is already beginning to emerge in the form of biosensors, said Hiroaki Yokota, a nanomotor researcher at Osaka University in Japan. These are instruments that researchers use to detect a very specific piece of DNA that may be related to disease. Such sensors "enable us to detect only a few DNA molecules that contain specific sequences and thus possibly diagnose patients as having such specific sequences related to a cancer gene or not," he said.
Down the road, it is anticipated that nanomotors will play an active role in clinical treatment. For example, these ultra-small devices could be injected along with drugs that kill cancer cells or tumors, Tan said. When the drugs reach the disease site, the nanomotors would make the drug molecules attach and stick to the cancer cell membrane, Tan said.
Perhaps more importantly, the motors' precision would give them the ability to prevent the drugs from attaching to noncancerous molecules or healthy parts of the body -- eliminating the debilitating effects, for example, of chemotherapy drugs.
Some scientists believe that nanomotors could also be used in so-called "test-tube manufacturing." This approach turns traditional manufacturing on its head. Where traditional manufacturing creates structures from existing materials or parts, test-tube manufacturing involves building structures from the smallest molecular or atomic components.

Sensor function of DNA nanomotors

[nucal]

In my opinion, calling these things nanomotors is a bit of a misnomer, since they are really undergoing cycles of melting (to cause the hairpinning) and reannealing (to straighten the DNA strand). But, this melting cycle can do work to move things around - which is the strict definition of a motor. Will these things work as a drug targeting strategy for cancer cells? Maybe someday, but that's a long ways off until the problem of inducing specific DNA melting in vivo is solved (a non-trivial issue).

On the other hand, the sensor function seems to be more practical right now. Any type of hybridization strategy requires and interaction between the target and the "test" sample from some source (cancer cell, crime scene evidence, etc.) to generate a signal. Most of the current technologies require processing the sample to add a detectable marker, either radioactivity or fluorescence, which is then detected when it binds to the target stuck to some matrix.

For DNA nanomotors to act as a sensor, sample DNA would bind to the DNA target to interfere with motor function - I'm guessing to leave it in a semi-melted state. One key here is that the DNA nanomotor has the detection method built into the target - since when the DNA melts, the fluorescence is emitted (e.g. through resonance energy transfer - RET [molecularprobes.com]). Having the detector in the target eliminates a lot of sample processing steps and so increases the sensitivity of detection. Adding motor function may enable this to be linked to some sort of electronic relay - further increasing sensitivity.

The real advance here is that by doing this with a single DNA strand it is much easier to engineer a "detector" sequence into the nanomotor than it would be if multiple strands are required for different steps in motor function.

Give credit where credit is due

[ChaoticPenguin]

The first such concept was demonstrated years ago by Andrew Turberfield of Oxford. Read about it, for example, here [bbc.co.uk]. The work reported in the current article is a step forward, not revolutionary. P.S. Incidentally, Turberfield was trained as a low temperature physicist before moving into biology. Just goes to show that inter-disciplinary research often results in cool ideas!