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In The Future LED Light May Help In Locating Tumors

A system developed by chemist Bruce Weisman may one day be used to locate cancer tumors that are tagged by anti-body linked carbon nanotubes. How human tissue absorbs short-wave infrared light depends on the wavelength of the incoming light. By performing spectral analysis of the light coming through the skin one can establish the depth of the tissue. Nanotube beacons can then be located using the three-dimensional coordinates determined by the analysis.

The spectral triangulation system developed by Rice chemist Bruce Weisman and his colleagues is intended to pinpoint targeted cancer tumors tagged with antibody-linked carbon nanotubes. It is described in a paper in the Royal Society of Chemistry journal Nanoscale.
Because the absorption of short-wave infrared light in tissues varies with its wavelength, spectral analysis of light coming through the skin can reveal the depth of tissue through which that light has passed. This allows the three-dimensional coordinates of the nanotube beacon to be deduced from a small set of noninvasive optical measurements.
The Rice technique relies on the fact that single-walled carbon nanotubes naturally fluoresce at short-wave infrared wavelengths when excited by visible light. A highly sensitive detector called an InGaAs (indium gallium arsenide) avalanche photodiode made it possible to read faint signals from nanotubes up to 20 millimeters deep in the simulated tissue used for lab tests.
“We’re using an unusually sensitive detector that hasn’t been applied to this sort of work before,” said Weisman, a recognized pioneer for his discovery and interpretation of near-infrared fluorescence from single-walled nanotubes.

The full article can be read at Rice University's web site.