Bifunctional Gallium-68 Chelators: Past, Present, and Future

This article reviews the development of bifunctional chelates for synthesising 68Ga radiopharmaceuticals. It structures the chelates into groups of macrocycles, nonmacrocycles, and chimeric derivatives. The most relevant bifunctional chelates are discussed in chelate structure, parameters of 68Ga-labeling, and stability of the 68Ga-chelate complexes. Furthermore those derivatives are included, where 67Ga was applied instead of 68Ga. A particular feature discussed is the ability of certain bifunctional chelate structures to function in kit-type preparation of the 68Ga radiopharmaceuticals. Currently, nonmacrocyclic and chimeric derivates attract particular attention such as THP-derivates and DATA-derivates.