Metal nanoshells as a contrast agent in near-infrared diffuse optical tomography

The plasma resonance peak of metal nanoshells can be tuned to the near-infrared region (700-900 nm), making them have great potential in biological and biomedical applications. Gold nanoshells has been synthesized and characterized as a contrast agent for diffuse optical tomography. A unique advantage of the nanoshells is their tremendous absorptivity. Spectral measurements indicate that the absorption cross-section of each nanoshell is 40,000 times larger than that of an Indocyanine Green (ICG) molecule, suggesting that the nanoshells are a much more efficient absorption agent than ICG molecules. Tissue-like phantom experiments using the nanoshells were performed using our diffuse optical imaging system and absorption images were successfully obtained through a finite element based reconstruction algorithm.