Labeling of bifunctional chelating agent, MAG3, with carrier-free Re

Hashimoto, Kazuyuki; Wan, K. W. H. B. B.*; Matsuoka, Hiromitsu

The radioisotopes of rhenium (Re and Re) are attractive radionuclides for radiotherapy because of their energetic beta particles and gamma rays suitable for imaging. Mercaptoacetyltriglycine, MAG3 (NS ligand), is a useful bifunctional ligand in labeling monoclonal antibodies with metallic radionuclides. In this study, the labeling of MAG3 with carrier-free Re from a W/Re generator was investigated in detail. The Re-MAG3 complex was synthesized by the direct labeling method and by the indirect labeling method using a transfer ligand (citric acid or gluconic acid). The dependence of the labeling yield upon the reaction conditions such as the concentrations of tin(II) chloride dihydrate as a reducing agent, S-benzoyl MAG3 and the transfer ligand, pH, temperature, reaction time and the addition of a carrier was examined. The labeling yield of Re-MAG3 synthesized by the all method was over 90% under the optimum conditions.