Abstract
The typical method for creating targeted contrast agents requires covalent conjugation of separate targeting and fluorophore domains. In this study, we demonstrate that it is possible to create near-infrared (NIR) fluorophores with different tissue specificities driven by their inherent chemical structures. Thus, a single compact molecule performs both targeting and imaging. We use this strategy to solve a major problem in head and neck surgery: the identification and preservation of parathyroid and thyroid glands. We synthesized 700-nm and 800-nm halogenated fluorophores that show high uptake into these glands after a single intravenous (IV) injection of 0.06 mg kg(-1) in a pig. By using a dual-channel NIR imaging system, we observed-in real time and with high sensitivity-the unambiguous distinction of parathyroid and thyroid glands simultaneously in the context of blood and surrounding soft tissue. This novel technology lays a foundation for performing head and neck surgery with increased precision and efficiency along with potentially lower morbidity, and it provides a general strategy for developing targeted NIR fluorophores.