Near-infrared (NIR) fluorescence-emitting small organic molecules for cancer imaging and therapy

Near-infrared (NIR) fluorophores have unique features that endow them with several advantages over conventional shorter wavelength emitting dyes. As a result, they have been widely utilized as fluorescence and photoacoustic imaging agents, as well as photodynamic and photothermal therapeutic agents. However, non-targeting NIR fluorescence-emitting organic molecules have the drawback of low selectivity toward tumors, which potentially results in severe side effects caused by damage to normal tissues. Thus, the development of NIR fluorophore-based substances that target tumors is a highly active area in medicinal chemistry research. Research efforts carried out thus far have led to the development of a number of NIR fluorophore-based, tumor imaging and therapeutic agents. The discussion in this review focuses on the results of research reported in the 2012-2021 period, giving particular emphasis to studies of NIR small organic dye-based imaging and therapeutic agents that are designed utilizing cancer-selective strategies.