Preparation of New Core 99Tcm (CO)2(NO)2+ and Its Derivatives 99Tcm (CO)2(NO)L (L=DTPA， EDTA， EHIDA) in Aqueous Solution

In order to develop a new method for the preparation of the ⁹⁹Tc^m (CO)₂(NO)-L (L=DTPA, EDTA, EHIDA) complexes in aqueous solution, two different procedures were developed: one is formation of the metal-tricarbonyl-ligand complex and subsequent nitrosylation; another is nitrosylation of the metal-tricarbonyl precursor followed by reaction with the ligand. The optimal labeling conditions were studied. Results of TLC and HPLC indicate that the radiochemical yields derived from the two methods list above are all more than 90%. It’s an easier new way to prepare ⁹⁹Tc^m (CO)₂(NO)-L complexes in aqueous solution with high efficiency. The newly developed ⁹⁹Tc^m (CO)₂(NO)-L complexes are stable at room temperature during 1 half-life of the isotope. At the same time, the lipophility and net charge of ⁹⁹Tc^m (CO)₂(NO)-Lcomplexes are also changed comparing with that of corresponding ⁹⁹Tc^m(CO)₃⁺core complexes. It opens a new field for designing radiopharmaceuticals. 