Authors: Y.-S. Yang, S. Vaithilingam, H.T.-J. Ma, B.T. Khuri-Yakub, S. Guccione
Affilation: Stanford University, United States
Pages: 708 - 711
Keywords: photoacoustic tomagraphy, gold, nanosphere, nanoparticle, contrast agent
Photoacoustic tomography (PAT) utilizes non-ionizing energy to obtain structural/functional information with high spatial resolution and sensitivity. Heterogeneous absorption of optical energy in biological tissues results in differentially expressed acoustic signals yielding spatial/temporal information. A critically underdeveloped area in PAT is the development of contrast agents. Gold-containing nanoparticles can be a good choice due to their high bio-compatibility, low toxicity, high feasibility of surface modification/conjugation. Here we present a broad evaluation of gold-containing nanoparticle for PAT contrast agents with different sizes and optical absorption properties. Gold nanospheres with diameters of 2-60nm generated PAT contrast enhancement at visible-light region. The enhancement increased with increasing size. Encapsulation of gold nanospheres using liposomes provides increased enhancement and shift in optical absorption to above 600nm. The highest contrast enhancement was obtained using PDA encapsulating 5nm-Au nanosphere. In summary we have demonstrated the capability of preparing the optimal contrast agents for PAT by fine-tuning the size, and the composition of the nanoparticles. We have also synthesized gold nanorods with optical absorption in the near-IR region. They can be encapsulated in the liposomes in a similar manner. Characterization of these nanoparticles is underway. Future work also focuses on modifying the liposome and in-vivo evaluation for targeted delivery.