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Published May 2010 | Supplemental Material + Accepted Version
Journal Article Open

Near infrared photoacoustic detection of sentinel lymph nodes with gold nanobeacons


Detection of sentinel lymph node (SLN) using photoacoustic imaging is an emerging technique for noninvasive axillary staging of breast cancer. Due to the absence of intrinsic contrast inside the lymph nodes, exogenous contrast agents are used for photoacoustic detection. In this work, we have demonstrated near infrared detection of SLN with gold nanobeacons (GNBs) providing the photoacoustic contrast in a rodent model. We found that size dictates the in vivo characteristics of these nanoparticles in SLN imaging. Larger nanobeacons with high payloads of gold were not as efficient as smaller size nanobeacons with lower payloads for this purpose. Colloidal GNBs were designed as a nanomedicine platform with "soft" nature that is amenable to bio-elimination, an essential feature for in vivo efficacy and safety. The GNBs were synthesized as lipid- or polymer-encapsulated colloidal particles incorporating tiny gold nanoparticles (2–4 nm) in three tunable sizes (90 nm, 150 nm and 290 nm). Smaller GNBs were noted trafficking through the lymphatic system and accumulating more efficiently in the lymph nodes in comparison to the bigger nanoagents. At 20 min, the GNBs reached the SLN and were no longer observed within the draining lymphatic vessel. Within 1 h post-injection, the contrast ratio of the lymph nodes with the surrounding blood vessels was 9:1. These findings were also supported by analytical measurements of the ex vivo tissue samples. Results indicate that cumulative nanoparticle deposition in lymph nodes is size dependent and that high payloads of gold, although offering greater contrast in vitro, may yield nanoagents with poor intradermal migration and lymphatic transport characteristics.

Additional Information

© 2010 Elsevier Ltd. Received 24 November 2009; Accepted 27 January 2010; Available online 20 February 2010. The financial support from the AHA under grant number 0835426N (DP), from NIH under grant numbers NS059302, CA119342 (GML), HL073646 (SAW), U54 CA136398, R01EB000712, R01NS046214, EB008085 (LW) is greatly appreciated. L.W. has a financial interest in Microphotoacoustic, Inc. and Endra, Inc., which, however, did not support this work.

Attached Files

Accepted Version - nihms177064.pdf

Supplemental Material - mmc1.doc


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