Nanoscopic gold spheres can be reversibly bound to DNA strands reversibly bound to DNA strands

Dec 05, 2004

How can individual components be assembled into larger functional units? And how can robot arms, for example, be made to "grab" specific nano-objects-and to release them at the right moment? The field of biotechnology presents interesting approaches to these problems. Researchers at the University of Dortmund have now developed an elegant method to link nanoparticles reversibly: they use short DNA strands to cause gold spheres to aggregate "on demand" and then to separate again, also "on demand".

The "genetic molecule" DNA has already proven itself as a nanoconstruction material; the specific base pairing of mutually complementary DNA regions puts this material into a position that promotes organization into defined structures.

A team headed by Christof M. Niemeyer has now used this property of single DNA strands to link together nanoscopic gold particles. The principle works as follows: The single strands of DNA with two different sequences, A and B, are attached to tiny spheres of gold. Free DNA strands are then added as "glue". These consist of three regions: Region A' is exactly complementary to DNA A and immediately binds to the A strands on the gold spheres. After A' comes region B', which is the counterpart to DNA B and thus binds to the B strands on the gold spheres. In this manner, the gold spheres are linked into small clumps.

The third region of the "glue" DNA, called C', is complementary to neither DNA A nor DNA B, and thus remains unaffected. This end acts as a kind of "tear-away strap" when it is time to separate the gold spheres from each other. The "glue remover" is a single strand of DNA that is exactly complementary to the glue DNA A'B'C', and so consists of regions A, B, and C. This is added to the mixture, and as soon as its C end "discovers" the free C' end (the "strap") on the glue DNA, it binds to it. The entire strip of "glue" then detaches to form a complete double strand with the glue-dissolving DNA. The gold spheres are thus separated once again and and revert back to their initial state. Addition of more single strands of glue DNA, can then reinitiate the aggregation.

"Our concept," says Niemeyer, " could be the basis for the production of nanomaterials with programmable functions."

Source: University of Dortmund

Explore further: Nanoparticles release drugs to reduce tooth decay

Related Stories

New nanodevice defeats drug resistance

Mar 02, 2015

Chemotherapy often shrinks tumors at first, but as cancer cells become resistant to drug treatment, tumors can grow back. A new nanodevice developed by MIT researchers can help overcome that by first blocking ...

A layered nanostructure held together by DNA

Mar 20, 2014

(Phys.org) —Dreaming up nanostructures that have desirable optical, electronic, or magnetic properties is one thing. Figuring out how to make them is another. A new strategy uses the binding properties ...

Traces of DNA exposed by twisted light

Oct 28, 2013

Structures that put a spin on light reveal tiny amounts of DNA with 50 times better sensitivity than the best current methods, a collaboration between the University of Michigan and Jiangnan University in China has shown.

Recommended for you

Nanoparticles release drugs to reduce tooth decay

5 hours ago

Therapeutic agents intended to reduce dental plaque and prevent tooth decay are often removed by saliva and the act of swallowing before they can take effect. But a team of researchers has developed a way ...

Combining magnetism and light to fight cancer

10 hours ago

By combining, in a liposome, magnetic nanoparticles and photosensitizers that are simultaneously and remotely activated by external physical stimuli (a magnetic field and light), scientists at the Laboratoire ...

Natural nanocrystals shown to strengthen concrete

Mar 31, 2015

Cellulose nanocrystals derived from industrial byproducts have been shown to increase the strength of concrete, representing a potential renewable additive to improve the ubiquitous construction material.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.