Development of [201 Tl](III) oxinate complex for in vitro cell labeling

Background: the incorporation of thallium-201 into 8-hydroxyquinoline was targeted for cell labeling due to interesting physical properties and wide availability of this nuclide as a single photon emission computed tomography (spect) radionuclide. materials and methods: thallium-201 (t1/2=3.04 d) in tl^+ form was converted to tl^3+ cation in presence of o3/6m hcl and di-isopropyl ether, controlled by radiothin layer chromatography (rtlc) /gel electrophoresis methods. the final evaporated activity reacted with ethanolic 8-hydroxy-quinoline (oxine) solution in normal saline to yield [201 tl](iii)oxinate at room temperature after 0.5 h, followed by solid phase extraction/purification using c18 sep-pak column and partition coefficient determination for water/lipid solubility. in vitro red blood cell (rbc) labeling was also performed. 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 rbc labeling. the cell uptake ratio was 0.47 after 240 min. conclusion: [201 tl](iii) oxinate used in this study is a widely available agent for use in rbc labeling studies in biology, medicine and various other research areas.