Photoacoustic tomography with novel optical contrast agents based on gold nanocages or nanoparticles containing near-infrared dyes

Poly(ethylene glycol)-coated Au nanocages have been evaluated as a potential near-infrared (NIR) contrast agent for photoacoustic tomography (PAT). Previously, Au nanoshells were found to be an effective NIR contrast agent for PAT; however, Au nanocages, with their more compact sizes (<50 nm compared to >100 nm for Au nanoshells) and larger optical absorption cross-sections, should be better suited for in vivo applications. In this study, we tested Au nanocages as a contrast agent for PAT. The result suggests that Au nanocages are promising contrast agents for our applications. We also present PAT results when novel, dye-containing nanoparticles are used as contrast agents.