The team has pioneered work on the use of nanopores—tiny chambers that mimic the ion channels in the membranes of cells—for the detection and identification of a wide range of molecules, including DNA. Ion channels are the gateways by which the cell admits and expels materials like proteins, ions and nucleic acids. The typical ion channel is so small that only one molecule can fit inside at a time.
By tethering gold nanoparticles (large spheres in top image) to the nanopore (violet), the temperature around the nanopore can be changed quickly and precisely with laser light, allowing scientists to distinguish between similar molecules in the pore that behave differently under varied temperature conditions.
Previously, team members inserted a nanopore into an artificial cell membrane, which they placed between two electrodes. With this setup, they could drive individual molecules into the nanopore and trap them there for a few milliseconds, enough to explore some of their physical characteristics.
"A single molecule creates a marked change in current that flows through the pore, which allows us to measure the molecule's mass and electrical charge with high accuracy," says Joseph Reiner, a physicist at VCU who previously worked at NIST. "This enables discrimination between different molecules at high resolution. But for real-world medical work, doctors and clinicians will need even more advanced measurement capability."
A goal of the team's work is to differentiate among not just several types of molecules, but among the many thousands of different proteins and other biomarkers in our bloodstream. For example, changes in protein levels can indicate the onset of disease, but with so many similar molecules in the mix, it is important not to mistake one for another. So the team expanded their measurement capability by attaching gold nanoparticles to engineered nanopores, "which provides another means to discriminate between various molecular species via temperature control," Reiner says.
The team attached gold nanoparticles to the nanopore via tethers made from complementary DNA strands. Gold's ability to absorb light and quickly convert its energy to heat that conducts into the adjacent solution allows the team to alter the temperature of the nanopore with a laser at will, dynamically changing the way individual molecules interact with it.
"Historically, sudden temperature changes were used to determine the rates of chemical reactions that were previously inaccessible to measurement," says NIST biophysicist John Kasianowicz. "The ability to rapidly change temperatures in volumes commensurate with the size of single molecules will permit the separation of subtly different species. This will not only aid the detection and identification of biomarkers, it will also help develop a deeper understanding of thermodynamic and kinetic processes in single molecules."
The team is researching ways to improve semiconductor-based nanopores, which could further expand this new measurement capability.
*J.E. Reiner, J.W.F. Robertson, D.L. Burden, L.K. Burden, A. Balijepalli and J.J. Kasianowicz. Temperature sculpting in yoctoliter volumes. Journal of the American Chemical Society, DOI: 10.1021/ja309892e. Jan. 24, 2013.
Chad Boutin | EurekAlert!
Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy