Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

ASU researchers ’wire’ DNA to identify mutations

09.12.2005


A team of ASU researchers led by Nongjian Tao and Peiming Zhang has developed a new, breakthrough technique for the detection of DNA mutations.



Their results, published in the journal Proceedings of the National Academy of Sciences, demonstrate for the first time, the possibility of directly identifying these mutations, or single nucleotide polymorphisms (SNPs), by means of measuring the electrical conductance of a single DNA molecule.

SNPs are buried in the 3 billion DNA bases of the human genome. On average, SNPs occur about once in every 1,000 DNA bases, though not every SNP found will necessarily cause a disease mutation. Cataloging these subtle DNA differences among the populace will aid the ongoing quest to understand and prevent disease.


"There is a high demand to track mutations for cancer research or future applications in personalized medicine," said Zhang, an associate research professor of the Center for Single Molecule Biophysics in the Biodesign Institute at ASU. "Currently, the main issue in doing this type of detection is that it is still costly and time consuming."

The team’s breakthrough relies on an intrinsic physical property of DNA, conductivity, or how well the molecule can carry an electrical current. Depending on the experimental conditions, DNA has been previously shown to act as both a conductor and insulator.

"We have developed a technology that allows us to wire single molecules into an electrical circuit," said Tao, professor of electrical engineering in the Ira A. Fulton School of Engineering and also a researcher in the Center for Solid State Electronics Research. "We can now directly read the biological information in a single DNA molecule."

Measurement of DNA conductivity first requires wiring the molecule into an electrical circuit. "There are two things required to make a reliable measurement," said Tao. "One is that the DNA has to be tethered between two electrodes and the other is that it should be done in a slightly salty, water environment to minimize any perturbations to the structure of the molecule." Electrical engineering graduate students Joshua Hihath and Bingqian Xu carried out the measurement.

"We measure a small current through the molecules using a setup developed in our lab." said Tao. "It’s a conceptually simple setup. You just bring two electrodes together, separate them apart, make the measurement and repeat."

In the technique, chemical linker groups that form a tight bond with gold electrodes are attached to the ends of DNA. A drop of a DNA solution is then placed between the two electrodes. The DNA sticks to the surface of the electrodes spontaneously.

As the tip is pulled away and the two electrodes teased apart, the molecules of DNA are eventually dispersed to the point of measuring the current of a single DNA molecule.

For a proof of concept of the potential for measuring SNPs, the group used DNA of 11 or 12 bases in length dissolved in a physiologically relevant saline solution. From one electrode tip, a small current, or bias is used to probe the internal electronic states of DNA. By measuring the conductance, the team was able to understand the sequence information in the DNA and whether there was a mismatch in comparison to a normal DNA sequence.

What they found was that just a single base pair mutation in a DNA molecule, such as substituting an A for a G, can cause a significant change in the conductance of the molecule. The measurement is extremely sensitive, as the alteration of a single base in the DNA stack can either increase or decrease the conductivity of a DNA helix, depending on the type of mismatched base.

Not only was the group the first measure SNPs in this manner, but they were also the first to make the measurement in a water environment relevant to that found in biological systems.

How the current flows through the DNA molecule is still a subject of speculation. "One idea is that there is a tunneling process," said Tao.

The DNA has properties which make the electrons easier to tunnel through, just like lowering a hill for a marathon runner.

"The other may be a charge-hopping phenomenon, where the electrons get trapped in the DNA and then hop from the electrode to the DNA to the second electrode."

The next goal of the research is to make the measurement steps easier and faster through automation, which will allow many different DNA sequences to be analyzed at once.

Joe Caspermeyer | EurekAlert!
Further information:
http://www.asu.edu
http://www.fulton.asu.edu
http://www.biodesign.org

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

On the way to developing a new active ingredient against chronic infections

21.08.2017 | Life Sciences

Smart Computers

21.08.2017 | Information Technology

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>