Synthesis and evaluation of a novel 99mTc nitrido radiopharmaceutical with alendronate dithiocarbamate as a potential bone-imaging agent

Currently, a popular strategy for designing novel radioprobes as bone-imaging agents is based on the concept of bifunctional radiopharmaceuticals. Considering the dithiocarbamate ligand can act as a suitable bifunctional linking agent to attach technetium-99m (Tc-99m) to corresponding target molecules, in this study, alendronate dithiocarbamate (ALNDTC) was synthesized and radiolabeled with [(TcN)-Tc-99m](2+) core by ligand exchange reaction to produce (TcN)-Tc-99m-ALNDTC complex, for the potential use as a novel probe for bone imaging. The radiochemical purity of the complex was over 90%. The complex was stable in vitro and could bind to hydroxyapatite. The partition coefficient result indicated it was hydrophilic, and an evaluation of biodistribution in mice indicated that the complex exhibited a higher bone uptake than did Tc-99m-labeled methylenediphosphonate (Tc-99m-MDP). Further, single photon emission computed tomography imaging study indicated clear accumulation in bone, suggesting that (TcN)-Tc-99m-ALNDTC would be a promising candidate for bone imaging.