“Raman scattering provides information on the ways molecules vibrate, which is equivalent to taking their fingerprint. It’s a bit like a bar code,” said the internationally renowned professor. “Raman signals are specific for each molecule and thus useful in identifying these molecules.”
Richard Martel and his research team at the Department of Chemistry of the Université de Montréal have discovered a method to improve detection of the infinitely small. Their discovery is presented in the November 24 online edition of the journal Nature Photonics. Credit: Universite de Montreal
Applications of the discovery: retail, banks, hospitals, etc.
The discovery by Martel’s team is that Raman scattering of dye-nanotube particles is so large that a single particle of this type can be located and identified. All one needs is an optical scanner capable of detecting this particle, much like a fingerprint.
“By incorporating these nanoparticles in an object, you can make it perfectly traceable,” he said. Due to their unique structure, carbon nanotubes, which are electrically conductive, can be used as containers for various molecules. Coupled with a dye, these nanoprobes can increase the complexity and strength of the received signal.
Nanoprobes, which are composed of around one hundred dye molecules aligned inside a cylinder, are 50,000 times smaller than a human hair. They are about one nanometre (nm) in diameter and 500 nm long, yet they send a Raman signal one million times stronger than the other molecules in the surrounding.
According to Professor Martel, the applications from this discovery are numerous. In medicine, nanoprobes could lead to improved diagnostics and better treatment by adhering to the surface of diseased cells. These specifically modified nanoprobes could, in effect, be grafted to bacteria or even proteins, allowing them to be easily identified.
One could also imagine custom officers scanning our passports with Raman multispectral mode (i.e., involving several signals). Nanoprobes could also be used in banknote ink, making counterfeiting virtually impossible.
The beauty of it, said Martel, is that the phenomenon is generalized, and many types of dyes can be used to make nanoprobes or tags, whose “bar codes” are all different. “So far, more than 10 different tags have been made, and it seems the sky’s the limit,” he said. “We could, in theory, create as many of these tags as there are bacteria and use this principle to identify them with a microscope operating in Raman mode.”
The story of Raman signals
Raman scattering mode is an optical phenomenon discovered in 1928 by the physicist Chandrasekhara Venkata Raman. The effect involves the inelastic scattering of photons, i.e. the physical phenomenon by which a medium can modify the frequency of the light impinging on it. The difference corresponds to an exchange of energy (wavelength) between the light beam and the medium. In this way, scattered light does not have the same wavelength as incidental light. The technique has become widely used since the advent of the laser in the industry and for research .
But until now, molecular Raman signals have been too weak to serve the needs of optical imaging effectively. So researchers have used other more sensitive techniques but which are less specific because they have no “bar code.” “It is technically possible, however, to enhance the Raman signals of molecules using rough metallic surfaces,” said Martel. “But their sizes limit the applications of Raman spectroscopy and imaging.”
By aligning dye molecules encapsulated in carbon nanotubes, the researchers were able to amplify the Raman signals of these molecules, which until now have not been strong enough to detect. The article presents experimental evidence of extraordinary scattering of visible light on a nanoparticle.Besides Richard Martel, E. Gaufrès, N. Y. Wa Tang, F. Lapointe, J. Cabana, M. A. Nadon, N. Cottenye, F. Raymond, all of the Université de Montréal, and T. Szkopek, University McGill, contributed to this discovery.
William Raillant-Clark | alfa
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
Migrating Cells: Folds in the cell membrane supply material for necessary blebs
23.11.2017 | Westfälische Wilhelms-Universität Münster
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
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....
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
23.11.2017 | Information Technology
23.11.2017 | Physics and Astronomy
23.11.2017 | Life Sciences