Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First Step Towards Electronic DNA Sequencing: Translocation Through Graphene Nanopores

27.07.2010
Researchers at the University of Pennsylvania have developed a new, carbon-based nanoscale platform to electrically detect single DNA molecules.

Using electric fields, the tiny DNA strands are pushed through nanoscale-sized, atomically thin pores in a graphene nanopore platform that ultimately may be important for fast electronic sequencing of the four chemical bases of DNA based on their unique electrical signature.

The pores, burned into graphene membranes using electron beam technology, provide Penn physicists with electronic measurements of the translocation of DNA.

The article, submitted on March 25, is published in the current issue of Nano Letters.

“We were motivated to exploit the unique properties of graphene — a two-dimensional sheet of carbon atoms — in order to develop a new nanopore electrical platform that could exhibit high resolution,” said Marija Drndiæ, associate professor in the Department of Physics and Astronomy in Penn’s School of Arts and Sciences and the paper’s senior author. “High resolution of graphene nanopore devices is expected because the thickness of the graphene sheet is smaller than the distance between two DNA bases. Graphene has previously been used for other electrical and mechanical devices, but up until now it has not been used for DNA translocation.”

The research team had made graphene nanopores in a study completed two years ago and in this study put the pores to work.

To conduct the experiments, Drndiæ and postdoctoral fellow Christopher A. Merchant, together with Ken Healy, Meni Wanunu, Vishva Ray and other members from the Drndiæ lab made use of large-area graphene material developed by postdoctoral fellow Zhengtang Luo and Professor A.T. Charlie Johnson, both physicists at Penn. The team used a chemical vapor deposition, or CVD, method to grow large flakes of graphene and suspend them over a single micron-sized hole made in silicon nitride. An even smaller hole, the nanopore in the very center of the suspended graphene, was then drilled with an electron beam of a transmission electron microscope, or TEM.

Solid-state nanopores are proving to be invaluable tools for probing biology at the single-molecule level.

Graphene nanopore devices developed by the Penn team work in a simple manner. The pore divides two chambers of electrolyte solution and researchers apply voltage, which drives ions through the pores. Ion transport is measured as a current flowing from the voltage source. DNA molecules, inserted into the electrolyte, can be driven single file through such nanopores.

As the molecules translocate, they block the flow of ions and are detected as a drop in the measured current. Because the four DNA bases block the current differently, graphene nanopores with sub-nanometer thickness may provide a way to distinguish among bases, realizing a low-cost, high-throughput DNA sequencing technique.

In addition, to increase the robustness of graphene nanopore devices, Penn researchers also deposited an ultrathin layer, only a few atomic layers thick, of titanium oxide on the membrane which further generated a cleaner, more easily wettable surface that allows the DNA to go through it more easily. Although graphene-only nanopores can be used for translocating DNA, coating the graphene membranes with a layer of oxide consistently reduced the nanopore noise level and at the same time improved the robustness of the device.

Because of the ultrathin nature of the graphene pores, researchers were able to detect an increase in the magnitude of the translocation signals relative to previous solid state nanopores made in silicon nitride, for similar applied voltages.

The Penn team is now working on improving the overall reliability of these devices and on utilizing the conductivity of the graphene sheet to create devices with transverse electrical control over DNA transport. Specifically, this transverse electrical control may be achievable by carving graphene into nanoelectrodes and utilizing its conducting nature. Towards this goal, Michael Fischbein and Drndic have previously demonstrated nanosculpting of graphene into arbitrary structures, such as nanoribbons, nanopores and other shapes, published in Applied Physics Letters in 2008, creating a firm foundation for future research.

Research was conducted by Merchant, Healy, Wanunu, Ray, Neil Peterman, John Bartel, Michael D. Fischbein, Kimberly Venta, Luo, Johnson and Drndiæ of Penn’s Department of Physics and Astronomy.

The research was supported by a National Institutes of Health grant and also grants from the U.S. Department of Defense, Army Research Office, Penn Genome Frontiers Institute, Nano-Bio Interface Center at Penn, Nanotechnology Institute of the Commonwealth of Pennsylvania and Pennsylvania Department of Health. The Department of Health specifically disclaims responsibility for any analyses, interpretations or conclusions.

Jordan Reese | EurekAlert!
Further information:
http://www.upenn.edu

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>