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Carbon nanotube jungles created to better detect molecules

Date:
November 6, 2013
Source:
DOE/Lawrence Livermore National Laboratory
Summary:
Researchers have developed a new method of using nanotubes to detect molecules at extremely low concentrations enabling trace detection of biological threats, explosives and drugs.

The top view of the jungle canopy (hafnium thickness of 2.5 nanometers and gold thickness of 20 nanometers).
Credit: Image courtesy of DOE/Lawrence Livermore National Laboratory

Researchers from Lawrence Livermore National Laboratory (LLNL) and the Swiss Federal Institute of Technology (ETH) in Zurich have developed a new method of using nanotubes to detect molecules at extremely low concentrations enabling trace detection of biological threats, explosives and drugs.

The joint research team, led by LLNL Engineer Tiziana Bond and ETH Scientist Hyung Gyu Park, are using spaghetti-like, gold-hafnium-coated carbon nanotubes (CNT) to amplify the detection capabilities in surface-enhanced Raman spectroscopy (SERS).

SERS is a surface-sensitive technique that enhances the inelastic scattering of photons by molecules adsorbed on rough metal surfaces or by nanostructures.

Bond and her collaborators are using metal-coated nanotubes bunched together like a jungle canopy to amplify the signals of both the incident and Raman scattered light by exciting local electron plasmons.

Their real breakthrough, however, is discovering the use of an intermediate dielectric coating (hafnium) to block the quenching of the free electrons in the metal by the CNTs, allowing the nanotubes to function uninhibited. By preserving the electrons and enhancing the light through the use of nanotube jungles, the team is able to significantly increase the SERS' detection sensitivities in CNTs structures.

The hafnium coating enables the bunching of gold nanotubes that creates a thick canopy full of sensitive spots for detection. The nanotubes enable incident light to be trapped and focused at the numerous contact points and crevices, allowing the Raman-scattered light to pass through. This enables portable Raman devices to detect and identify specific airborne substances randomly.

"This is a very important discovery in our efforts to improve the use of SERS devices," Bond said. "We gained this valuable knowledge through multidisciplinary basic research and approaching the problem with a rational design."

Bond and Park hope their engineered material will eventually be used in portable devices to conduct on-site analysis of chemical impurities such as environmental pollutants or pharmaceutical residues in water. Other applications include the real-time point-of-care monitoring of physiological levels for the biomedical industry and fast screening of drugs and toxins for law enforcement.

"We are in the process of filing a patent for our new discovery," Bond said.


Story Source:

The above story is based on materials provided by DOE/Lawrence Livermore National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Ali Ozhan Altun, Seul Ki Youn, Nuri Yazdani, Tiziana Bond, Hyung Gyu Park. Metal-Dielectric-CNT Nanowires for Femtomolar Chemical Detection by Surface Enhanced Raman Spectroscopy. Advanced Materials, 2013; 25 (32): 4431 DOI: 10.1002/adma.201300571

Cite This Page:

DOE/Lawrence Livermore National Laboratory. "Carbon nanotube jungles created to better detect molecules." ScienceDaily. ScienceDaily, 6 November 2013. <www.sciencedaily.com/releases/2013/11/131106132027.htm>.
DOE/Lawrence Livermore National Laboratory. (2013, November 6). Carbon nanotube jungles created to better detect molecules. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2013/11/131106132027.htm
DOE/Lawrence Livermore National Laboratory. "Carbon nanotube jungles created to better detect molecules." ScienceDaily. www.sciencedaily.com/releases/2013/11/131106132027.htm (accessed July 26, 2014).

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