TY - GEN
T1 - Metallic nanoparticles as optoacoustic contrast agents for medical imaging
AU - Conjusteau, Andre
AU - Ermilov, Sergey A.
AU - Lapotko, Dmitri
AU - Liao, Hongwei
AU - Hafner, Jason
AU - Eghtedari, Mohammad
AU - Motamedi, Massoud
AU - Kotov, Nicholas
AU - Oraevsky, Alexander A.
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2006
Y1 - 2006
N2 - A contrast agent for optoacoustic imaging and laser therapy of early tumors is being developed based on gold nanocolloids strongly absorbing visible and near-infrared light. The optoacoustic signals obtained from gold nanospheres and gold nanorods solutions are studied. In the case of 100 nm nanospheres as an example, a sharp increase in the total area under the curve of the optoacoustic signal is observed when the laser fluence is increased beyond a threshold value of about 0.1 J/cm 2. The change in the optoacoustic signal profile is attributed to the formation of water vapor bubbles around heated nanoparticles, as evidenced via thermoacoustic microscopy experiments. It has been determined that, surprisingly, gold nanoparticles fail to generate detectable nanobubbles upon irradiation at the laser fluence of ~2 mJ/cm 2, which heats the nanoparticles up to 374°C, the critical temperature of water. Only when the estimated temperature of the particle reaches about 10,000°C, a marked increase of the optoacoustic pressure amplitude and a changed profile of the optoacoustic signals indicate nanobubble formation. A nanoparticle based contrast agent is the most effective if it can be activate by laser pulses with low fluence attainable in the depth of tissue. With this goal in mind, we develop targeting protocols that form clusters of gold nanocolloid in the target cells in order to lower the bubble formation threshold below the level of optical fluence allowed for safe laser illumination of skin. Experiments and modeling suggest that formation of clusters of nanocolloids may improve the sensitivity of optoacoustic imaging in the detection of early stage tumors.
AB - A contrast agent for optoacoustic imaging and laser therapy of early tumors is being developed based on gold nanocolloids strongly absorbing visible and near-infrared light. The optoacoustic signals obtained from gold nanospheres and gold nanorods solutions are studied. In the case of 100 nm nanospheres as an example, a sharp increase in the total area under the curve of the optoacoustic signal is observed when the laser fluence is increased beyond a threshold value of about 0.1 J/cm 2. The change in the optoacoustic signal profile is attributed to the formation of water vapor bubbles around heated nanoparticles, as evidenced via thermoacoustic microscopy experiments. It has been determined that, surprisingly, gold nanoparticles fail to generate detectable nanobubbles upon irradiation at the laser fluence of ~2 mJ/cm 2, which heats the nanoparticles up to 374°C, the critical temperature of water. Only when the estimated temperature of the particle reaches about 10,000°C, a marked increase of the optoacoustic pressure amplitude and a changed profile of the optoacoustic signals indicate nanobubble formation. A nanoparticle based contrast agent is the most effective if it can be activate by laser pulses with low fluence attainable in the depth of tissue. With this goal in mind, we develop targeting protocols that form clusters of gold nanocolloid in the target cells in order to lower the bubble formation threshold below the level of optical fluence allowed for safe laser illumination of skin. Experiments and modeling suggest that formation of clusters of nanocolloids may improve the sensitivity of optoacoustic imaging in the detection of early stage tumors.
KW - Bubble formation
KW - Clusters
KW - Gold nanoparticles
KW - Gold nanorods
KW - Optoacoustic imaging
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U2 - 10.1117/12.658065
DO - 10.1117/12.658065
M3 - Conference contribution
AN - SCOPUS:33646180378
SN - 0819461288
SN - 9780819461285
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Proceedings of SPIE - The International Society for Optical Engineering
T2 - 7th Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics - Photons Plus Ultrasound: Imaging and Sensing 2006
Y2 - 22 January 2006 through 26 January 2006
ER -