In vivo fluorescence imaging uses a sensitive camera to detect fluorescence emission from fluorophores in whole-body living small animals. To overcome the photon attenuation in living tissue, fluorophores with long emission at the near-infrared (NIR) region are generally preferred, such as small indocarbocyanine dyes. Near infrared (NIR) cyanine-based dyes, Cy5, Cy5.5 and Cy 7, are most commonly used for in vivo applications.