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Published January 25, 2011 | Supplemental Material + Accepted Version
Journal Article Open

Noninvasive Photoacoustic and Fluorescence Sentinel Lymph Node Identification using Dye-Loaded Perfluorocarbon Nanoparticles


The contrast mechanisms used for photoacoustic tomography (PAT) and fluorescence imaging differ in subtle, but significant, ways. The design of contrast agents for each or both modalities requires an understanding of the spectral characteristics as well as intra- and intermolecular interactions that occur during formulation. We found that fluorescence quenching that occurs in the formulation of near-infrared (NIR) fluorescent dyes in nanoparticles results in enhanced contrast for PAT. The ability of the new PAT method to utilize strongly absorbing chromophores for signal generation allowed us to convert a highly fluorescent dye into an exceptionally high PA contrast material. Spectroscopic characterization of the developed NIR dye-loaded perfluorocarbon-based nanoparticles for combined fluorescence and PA imaging revealed distinct dye-dependent photophysical behavior. We demonstrate that the enhanced contrast allows detection of regional lymph nodes of rats in vivo with time-domain optical and photoacoustic imaging methods. The results further show that the use of fluorescence lifetime imaging, which is less dependent on fluorescence intensity, provides a strategic approach to bridge the disparate contrast reporting mechanisms of fluorescence and PA imaging methods.

Additional Information

© 2011 American Chemical Society. Received for review September 3, 2010; and accepted December 07, 2010. Published online December 20, 2010. These studies were funded, in part, by grants from the NIH (R01 EB008111 and R01 EB008458 to S.A. and R01 EB000712, R01 EB008085, R01 CA134539, U54 CA136398, R01 EB010049, and 5P60 DK02057933 to L.V.W). L.V.W. has a financial interest in Microphotoacoustics, Inc. and in Endra, Inc., which, however, did not support this work.

Attached Files

Accepted Version - nihms259581.pdf

Supplemental Material - nn102274q_si_001.pdf


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