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REU

December 6, 2006

FRONTIERS IN MATERIALS SCIENCE
VINSE COLLOQUIUM SERIES

Dr. Bruce Weisman
Professor of Chemistry
Rice University
"Fluorescence of single-walled carbon nanotubes: An application in Physics, Chemistry, and Biomedicine"

Abstract.  The intrinsic near-IR fluorescence of semiconducting single-walled carbon nanotubes (SWNTs) provides a powerful tool for a variety of basic and applied investigations. Several current studies in this area will be surveyed. In one, near-IR video-microscopy is used to monitor the diffusional motions of SWNTs in ambient aqueous suspensions and to assess the thermally-induced bending deformations of (n,m)-identified  nanotubes. Analysis provides values of bending stiffness as a function of SWNT diameter. Another project is developing increasingly sensitive, sophisticated, and automated fluorimetric analysis methods for the detailed characterization of bulk samples. In support of this effort, single-nanotube measurements are exploring the variations in peak absorptivities and fluorescence quantum yields as a function of SWNT structure. Bulk  fluorescence spectroscopy of aqueous SWNT suspensions reveals species-dependent changes in E11 peak  positions, widths, and emission yields as a function of temperature. Finally, the ability of near-IR fluorescence microscopy to detect single SWNTs in biological media is illustrated by in vivo studies. In one, SWNTs are observed to enter the tissues of drosophila larvae following oral exposure through their food supply. Fluorescence microscopy allows us to quantitatively deduce the resulting tissue biodistributions. In another study, the circulation half-life of nanotubes in the blood stream of rabbits is measured to be 1.0 hours, and nanotubes are found to be taken up by the liver. This work may help form a foundation for the medical use of SWNTs as diagnostic and therapeutic agents. 

 
 
Vanderbilt University