Electrochemical separation of 132/135La theranostic pair from proton irradiated Ba target

Lanthanum-132/135 is an emerging theranostic pair of radiometals that might find widespread application in nuclear medicine. The present study describes the production of 132/135La in a low energy linear accelerator via natBa (p, n) 132/135La reaction. A robust and efficient method has been optimized for separation of no-carrier-added (NCA) 132/135La from the bulk irradiated target by electrodeposition of 132/135La on platinum anode. Near quantitative electrodeposition yield of 132/135La could be obtained when a potential of 6 V was applied for 20 min in an electrolyte solution (containing Ba and La) maintained at pH ∼ 3. After electrochemical separation, 132/135La could be obtained with > 99.99 % radionuclidic purity in a form suitable for radiopharmaceutical preparation. As a proof of concept, 132/135La-complex of a tumor avid peptide conjugate, namely, DOTA-E-[c(RGDfK)]2 was formulated with > 98 % yield and the radiolabeled complex maintained its integrity under physiological conditions over a prolonged period of time. Overall, this study amply demonstrates that electrochemical separation is a viable strategy for obtaining 132/135La for theranostic radiopharmaceutical preparation.