title: Preparation of no-carrier-added technetium-99m complexes via metal-assisted cleavage from a solid phase.
abstract: A novel method for the preparation of no-carrier-added (nca) complexes [99mTc(CO)3L] (L = diethylenetriamine or picolylamine-N-acetic acid) is described. The ligands were covalently bound to a solid support of organic polymers via formation of a tertiary amine from the chelating unit. This C-N bond to the solid phase is selectively cleaved during the formation of the technetium complexes by intramolecular nucleophilic attack of a remaining hydroxy ligand to the alpha-carbon. The complex [99mTc(CO)3L] is released into solution while uncomplexed ligand and uncleaved complex remain solid-phase bound. High specific activity technetium complexes can then be isolated by simple filtration. Cleavage yield depends on temperature, pH, and ligand. Up to 50% release from the solid phase could be achieved under optimized conditions. Corresponding to the 99mTc concentration, free ligand is present in concentrations lower than 10(-7) M. If a targeting vector is conjugated to these ligands, no-carrier-added radiopharmaceuticals can be prepared in that way.
authors.affiliation: Department of Inorganic Chemistry, University of Zürich, CH-8057 Zürich, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mundwiler
authors.forename: Lukas
authors.initials: L
authors.lastname: Candreia
authors.forename: Pascal
authors.initials: P
authors.lastname: Häfliger
authors.forename: Kirstin
authors.initials: K
authors.lastname: Ortner
authors.forename: Roger
authors.initials: R
authors.lastname: Alberto
mesh_terms: D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D005374:Filtration; D007202:Indicators and Reagents; D007700:Kinetics; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*; D021241:Spectrometry, Mass, Electrospray Ionization; D013667:Technetium / Q000737:chemistry*; D013696:Temperature
chemical_list: D007202:Indicators and Reagents; D008024:Ligands; D008670:Metals; D019275:Radiopharmaceuticals; D013667:Technetium