Plasmon-resonant Nanorods as Multifunctional Imaging Agents

Gold nanorods have several outstanding characteristics as optical contrastagents for biomedical imaging. Their strong optical absorption atnear-infrared (NIR) frequencies can be used to generate contrast for opticalcoherence tomography (OCT) imaging, and is well matched for detectionmodalities based on differential albedo. Nanorods can also be imageddirectly by two-photon luminescence (TPL) with single-particle sensitivity,and are sufficiently bright to support in vivo imaging applications. TPLimaging has been used to study the uptake of ligand-functionalized nanorodsby tumor cells. Lastly, nanorods are excellent converters of light energyinto heat, with direct application in photothermal therapy.