ABSTRACT
Note: e: electronic capture. 8.2.1 Bifunctional ChelatorsBifunctional chelating agents or bifunctional chelators (BFCs) contain a metal binding moiety and a chemically reactive functional group. The first sequesters the metallic radionuclide, while the latter provides the requisite chemistry for covalent attachment to the molecule of interest (e.g. protein, antibody, peptide) or nanosystem. Due to its chelating properties, 1,4,7,10tetraazacyclododecane-tetraacetic acid (DOTA) has had a significant impact on the field of diagnostic imaging. DOTA is one of the most
popular chelators used in medical diagnostics and preclinical studies, and it is the only chelator that has had a significant impact on all the major imaging modalities: magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computerised tomography (SPECT), and fluorescent imaging [1].The relatively large cavity size of DOTA and its derivatives (Fig. 8.1) enables the chelation of a variety of metal ions of different sizes, from the small and hard Ga3+ and Fe3+ ions to the large and soft lanthanide ions, such as Gd3+ and Eu3+, and common radiometals, such as 111In, 90Y, and 177Lu.
