Development of [201Tl](III)Oxinate complex for cell labeling

Introduction: Due to interesting physical properties and wide availability of thallium-201 as a SPECT radionuclide, the incorporation of this nuclide into 8-hydroxyquinoline for cell labeling was targeted. Methods: Thallium-201 (T1/2=3.04 d) in Tl+ form was converted to Tl3+ cation in presence of O3/6M HCl and di-isopropyl ether, controlled by RTLC/gel electrophoresis The final evaporated activity reacted with ethanolic 8-hydroxy-quinoline (oxine) solution in normal saline to yield [201Tl](III)oxinate at room temperature after 0.5 h, followed by solid phase extraction/purification using C18 Sep-Pak column Results: A radiochemical yield of more than 95% was obtained. Radiochemical purity of 92% was obtained using RTLC (>90% using HPLC) with specific activity of about 820 GBq/mmol. The tracer was stable in the final product and in presence of human serum at 37°C up to 6h. The partition coefficient of lopP=5.5 was obtained. The labeled compound was used in red blood cell (RBC) labeling. The cell uptake ratio was determined at 37°C up to 3 hours. Conclusion: The radiolabeled compound used in this study is a very inexpensive agent for use in cell labeling studies in biology, medicine and various research areas.