Re-engineering a simple nanotech device to make it more functional, Chinese scientists have developed an improved DNA tweezers that is able to capture, hold, and release a target molecule in a controlled manner. To do so, they took advantage of an alternative type of DNA base pair that allows a third strand of DNA to bind to a DNA double helix to form triple strand DNA under certain conditions. From a Nanowerk Spotlight, written by Michael Berger “The gripping potential of DNA nanotechnology“:
The exciting potential applications for DNA tweezers include their use in constructing various molecular devices dedicated to repairing a functional unit in a cell, harnessing the delivery of drug molecules to pathogenic cells, or assembling nanoscale devices.
There have been several earlier versions of similar DNA devices that can be operated to have open and close actions but it still has been a challenge to make them behave like real tweezers that can be handled to grasp and transfer an object. A team of Chinese scientists has now demonstrated a very simple design to fabricate a close-to-reality ‘grasp’ and ‘release’ function for a pair of DNA tweezers.
“The most challenging part to make this tweezer function available has to do with the structural simplicity of DNA tweezers that only have two mechanical arms — which is not a good setup for stably capturing something” Dr. Zhaoxiang Deng tells Nanowerk. “We have successfully circumvented this challenge thanks to the helical wrapping action of the DNA target around the tweezers’ arms during the formation of Hoogsteen bonds …, which greatly increases the probability for the target to be held between the tweezers’ arms.”
Based on this, Deng, a professor in the Department of Chemistry at the University of Science & Technology of China in Hefei, Anhui Province, together with his group, has successfully built a pair of DNA tweezers that can capture, hold, and release an object with easy control. They have reported their findings in the October 14, 2008 online edition of Journal of American Chemical Society (“Catch and Release: DNA Tweezers that Can Capture, Hold, and Release an Object under Control“).
Berger’s nicely illustrated article explains clearly how this improved tweezers functions. We are particularly happy to see that Prof Deng is thinking about how to eventually use his improved DNA nanodevice as one part of complex molecular machine systems.
“Also, if you imagine a nanofactory, you would need a mechanical hand to deal with many different tasks such as taking one part from an upstream worker, processing it and then handing it over to a downstream worker. In this process, a device like the one we have invented might find some uses even though it might be too early to think about these questions.”
The team is currently considering the integration of different DNA mechanical devices including the tweezers toward multiplexed and cooperative functions. Deng mentions that the simple demonstration devices that currently exist can only perform a simple task at a time; something which is not suitable for the construction of highly advanced nanofabrication systems and other nano devices. He notes that the ability to be integrated into larger assemblies is an inherent merit of DNA structures, which makes it possible to combine different functional units in a single platform and also allows them to be individually addressable after being coded using DNA sequences.