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Proceedings Paper

Multiple targeting in photoacoustic imaging using bioconjugated gold nanorods
Author(s): Pai-Chi Li; Chen-Wei Wei; Chao-Kang Liao; Cheng-Dah Chen; Kuei-Chen Pao; Churng-Ren Chris Wang; Ya-Na Wu; Dar-Bin Shieh
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Paper Abstract

Cancer cells presented altered surface molecules to encourage their growth and metastasis. Expression of oncogeneic surface molecules also play important roles in the prediction of clinical outcome and treatment response of anti-cancer drugs. It is thus conceivable that imaging of cancer lesions while simultaneously obtaining their pathogenic information at molecular level of as many oncogenic proteins as possible is of great clinical significance. Gold nanoparticles have been used as a contrast agent for photoacoustic imaging. In addition, gold nanoparticles can be bioconjugated to probe certain molecular processes. An intriguing property of gold nanoparticles is its ability to tailor its optical properties. For example, size effects on the surface plasmon absorption of spherical gold nanoparticles have shown that the peak optical absorption red-shifts with the increasing particle size. In addition, the optical absorption spectrum of cylindrical gold nanoparticles (i.e., gold nanorods) exhibits a strong absorption band that is directly related to the aspect ratio. With these unique characteristics, selective targeting can be achieved in photoacoustic molecular imaging. Specifically, gold nanorods with different aspect ratios can be bioconjugated to different antibodies. Multiple targeting and simultaneous detection can then be achieved by using laser irradiation at the respective peak optical absorption wavelength. In this study, photoacoustic multiple targeting using gold nanorods is experimentally demonstrated. We have chosen Her2 and CXCR4 as our primary target molecule as Her2 expression is associated with growth characteristics and sensitivity to Herceptin chemotherapy. On the other hand, CXCR4 expression predict the organ-specific metastatic potential of the cancer cells for clinical intervention in advance. Monoclonal antibody (mAb) against Her2/neu was conjugated to nanorods with several different aspect ratios. The agarose gel is suitable for photoacoustic signal acquisition. A wavelength tunable Ti-Sapphire laser was used for laser irradiation and a 1 MHz ultrasound transducer was used for acoustic detection. The optical wavelength of the laser was tuned between 800 nm and 940 nm, corresponding to gold nanorods of an aspect ratio ranging from 3.7 to 5.9. The results clearly show the potential of photoacoustic molecular imaging with multiple targeting in revealing different oncogene expression levels of the cancer cells.

Paper Details

Date Published: 6 March 2006
PDF: 10 pages
Proc. SPIE 6086, Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, 60860M (6 March 2006); doi: 10.1117/12.645248
Show Author Affiliations
Pai-Chi Li, National Taiwan Univ. (Taiwan)
Chen-Wei Wei, National Taiwan Univ. (Taiwan)
Chao-Kang Liao, National Taiwan Univ. (Taiwan)
Cheng-Dah Chen, National Chung-Cheng Univ. (Taiwan)
Kuei-Chen Pao, National Chung-Cheng Univ. (Taiwan)
Churng-Ren Chris Wang, National Chung-Cheng Univ. (Taiwan)
Ya-Na Wu, National Cheng Kung Univ. (Taiwan)
Dar-Bin Shieh, National Cheng Kung Univ. (Taiwan)

Published in SPIE Proceedings Vol. 6086:
Photons Plus Ultrasound: Imaging and Sensing 2006: The Seventh Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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