Birnessite: A New-Generation and Cost Effective Ion Exchange Material for Separation of Clinical-Grade 90Y from 90Sr/90Y Mixture

The widespread clinical utilization of Y-90 for preparation of target specific radiopharmaceuticals stipulates design of superior advanced materials for facile and cost effective separation of Y-90. We demonstrate for the first time potential of birnessite type phylomanganates for radiochemical separation of clinical grade Y-90 from Sr-90/Y-90 mixture. Sodium birnessite was synthesized by controlled oxidation of MnCl2.4H(2)O in presence of excess of NaOH and characterized thoroughly for structure, microstructure and purity. Ion exchange experiments in the presence of Sr-90/Y-90 equilibrium mixture confirmed the exceptionally high selectivity of synthetic sodium birnessite for exchanging Sr2+ ions and the conditions have been optimized to achieve radiochemically pure Y-90 (> 80% separation yield) meeting all the pharmaceutical requirements for its clinical use. Radionuclidic purity of Y-90 could be achieved to < 1 x 10(-4) % of Sr-90 which is well below the limit set internationally (2 x 10(-3) %). The separated Y-90 has been used to prepare Y-90 radiolabeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid coupled dimeric cyclic RGD peptide derivative [DOTA-E[c(RGDfK)](2)] and the biological efficacy of the radiotracer was established in C57/BL6 mice bearing melanoma tumors. The results indicated highly target specific radiotherapy suggesting the potential of sodium birnessite for cost effective radiochemical separation of Y-90.