24 February 2009 Enhanced sensitivity carbon nanotubes as targeted photoacoustic molecular imaging agents
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Photoacoustic imaging of living subjects offers high spatial resolution at increased tissue depths compared to purely optical imaging techniques. We have recently shown that intravenously injected single walled carbon nanotubes (SWNTs) can be used as targeted photoacoustic imaging agents in living mice using RGD peptides to target αvβ3 integrins. We have now developed a new targeted photoacoustic imaging agent based on SWNTs and Indocyanine Green (SWNT-ICG) with absorption peak at 780nm. The photoacoustic signal of the new imaging agent is enhanced by ~20 times as compared to plain SWNTs. The particles are synthesized from SWNT-RGD that noncovalently attach to multiple ICG molecules through pi-pi stacking interactions. Negative control particles had RAD peptide instead of RGD. We measured the serum stability of the particles and verified that the RGD/RAD conjugation did not alter the particle's absorbance spectrum. Finally, through cell uptake studies with U87MG cells we verified that the particles bind selectively to αvβ3 integrin. In conclusion, the extremely high absorption of the SWNT-ICG particles shows great promise for high sensitivity photoacoustic imaging of molecular targets in-vivo. This work lays the foundations for future in-vivo studies that will use the SWNT-ICG particles as imaging agents administered systemically.
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Adam de la Zerda, Adam de la Zerda, Zhuang Liu, Zhuang Liu, Cristina Zavaleta, Cristina Zavaleta, Sunil Bodapati, Sunil Bodapati, Robert Teed, Robert Teed, Srikant Vaithilingam, Srikant Vaithilingam, Te-Jen Ma, Te-Jen Ma, Omer Oralkan, Omer Oralkan, Xiaoyuan Chen, Xiaoyuan Chen, Butrus T. Khuri-Yakub, Butrus T. Khuri-Yakub, Hongjie Dai, Hongjie Dai, Sanjiv S. Gambhir, Sanjiv S. Gambhir, "Enhanced sensitivity carbon nanotubes as targeted photoacoustic molecular imaging agents", Proc. SPIE 7177, Photons Plus Ultrasound: Imaging and Sensing 2009, 71772K (24 February 2009); doi: 10.1117/12.809601; https://doi.org/10.1117/12.809601

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