An electrochemical generator for the continual supply of 213 Bi from 225 Ac for use in targeted alpha therapy applications.

Bismuth-213 is a radionuclide of interest for targeted alpha therapy and is supplied via a radiochemical generator system through the decay of ²²⁵ Ac. Radionuclide generators employ longer lived "parent" radionuclides to routinely supply shorter-lived "daughter" radionuclides. The traditional ²²⁵ Ac/ ²¹³ Bi radiochemical generator relies on an organic cation exchange resin where ²²⁵ Ac binds to the resin and ²¹³ Bi is routinely eluted. These resins degrade when they absorb large doses of ionizing radiation (>1 × 10 ⁶  Gy/mg), which has been observed when the loading activity of ²²⁵ Ac exceeds 2.59*10 ⁹  Bq (70 mCi). Herein we report the development of an electrochemical generator for the supply of ²¹³ Bi that has the potential to overcome this limitation. Bismuth-213 spontaneously electrodeposits onto nickel foils in 0.1 M hydrochloric acid at 70 °C. Using this method, we were able to plate an average of 73 ± 4 % of the ²¹³ Bi in solution and obtain a final ²¹³ Bi recovery of 65 ± 8 % in 0.1 M citrate pH 4.5 via reverse electrolysis using titanium as the cathode. The recovered ²¹³ Bi had an average radiochemical purity of >99.8 % and was successfully used to radiolabel DOTATATE with an average radiochemical yield of 85.1 % (not optimized).
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tara Mastren reports financial support was provided by Los Alamos National Laboratory. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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