Functionalized NaA nanozeolites labeled with 224,225Ra for targeted alpha therapy

The Ra-223, Ra-224, and Ra-225 radioisotopes exhibit very attractive nuclear properties for application in radionuclide therapy. Unfortunately the lack of appropriate bifunctional ligand for radium is the reason why these radionuclides have not found application in receptor-targeted therapy. In the present work, the potential usefulness of the NaA nanozeolite as a carrier for radium radionuclides has been studied. Ra-224 and Ra-225, alpha-particle emitting radionuclides, have been absorbed in the nanometer-sized NaA zeolite (30-70 nm) through simple ion exchange. Ra-224,Ra-225-nanozeolites exhibited very high stability in solutions containing physiological salt, EDTA, amino acids, and human serum. To make NaA nanozeolite particles dispersed in water their surface was modified with a silane coupling agent containing poly(ethylene glycol) molecules. This functionalization approach let us covalently attach a biomolecule to the NaA nanozeolite surface.