Rapid insertion of bismuth radioactive isotopes into texaphyrin in aqueous media

Radioisotopes 213Bi and 207Bi were successfully inserted into a water-soluble and tumor-targeting texaphyrin ligand. The reaction with 207Bi(OAc)3 proceeds in about 15 min in aqueous media without the use of any organic base. The Bi(III) texaphyrin complex formed (3) is stable in aqueous media even in the presence of an excess of competitive chelators (EDTA or citric acid), as well as in human blood plasma. These results validate texaphyrins as potential candidates for coordinating bismuth radionuclides and set the stage for their use in targeted alpha therapy (TAT).