Bifunctional chelators: An important tool in the development of inorganic pharmaceuticals

Metal ion-based pharmaceuticals now play an important role in both the diagnosis and treatment of patients. The design of modern inorganic pharmaceuticals for imaging or radiotherapy often consists of a biological targeting vector and a bifunctional ligand for coupling a diagnostic or therapeutic metal ion with the targeting vector. Bifunctional ligands may serve only to prevent the release of adventurous metal ions in the body or play a second role in imparting new physical features to the metal ion that aid in diagnosis. Given that so many bifunctional ligands are available to choose from, it is important to understand the features of these molecules that serve the desired application best. This short review summarizes some key factors to consider which choosing a bifunctional ligand for a particular imaging or therapeutic application.