Preparation and Stability Evaluation of Small Interference RNA Radiolabeled With ⁹⁹Tc^m

This study was to develop an available method of radiolabeling siRNA via conjugation with chelator of S-acetyl NHS-MAG₃, and to evaluate its radiolabeled efficiency and stability in vitro. At room temperature, the labeling efficiency reaches (73.4±3.0)% under the reaction condition of reaction time above 1 h, and ρ (SnCl₂•2H₂O)<2 g/L. After Sephadex G25 purification, the radiochemical purity is no less than 92% and the specific activity is up to 25.9 PBq/mol. In different mediums of saline and fresh human serum, the radiochemical purity keeps high stability in room temperature and 37℃. ⁹⁹Tc^m-labeled siRNA has the same targeted inhibition activity as non-labeled siRNA.