Matching Chelators to Radiometals for Positron Emission Tomography Imaging-Guided Targeted Drug Delivery

Positron emission tomography (PET) is a functional imaging modality that measures pathophysiology status of disease noninvasively, and has become a key component for innovative drug delivery system (DDS) studies recently. The development of multifunctional chelating agents is critical for developing PET radiopharmaceuticals and therefore has become a hot and demanding research topic recently. The optimal chelators should be readily attached to biomolecules covalently, able to form stable complexes with radiometals, and demonstrate good bio-distribution pattern in vivo. Indeed, the selection of suitable chelators can facilitate the development of an effective PET imaging probe by improving targeting properties and providing favorable in vivo pharmacokinetics of radiolabeled probes. This review focuses on the recent developments of multifunctional chelators that are suitable for both imaging and radiation therapy.