Retention studies of recoiling daughter nuclides of 225Ac in polymer vesicles

• First reported loading of 213Bi and 225Ac in polymer vesicles (i.e. polymersomes).
• Encapsulating 225Ac in polymersomes results in up to 69 % recoil retention of 221Fr.
• Encapsulating 225Ac in polymersomes results in up to 53 % recoil retention of 213Bi.

Alpha radionuclide therapy is steadily gaining importance and a large number of pre-clinical and clinical studies have been carried out. However, due to the recoil effects the daughter recoil atoms, most of which are alpha emitters as well, receive energies that are much higher than the energies of chemical bonds resulting in decoupling of the radionuclide from common targeting agents. Here, we demonstrate that polymer vesicles (i.e. polymersomes) can retain recoiling daughter nuclei based on an experimental study examining the retention of 221Fr and 213Bi when encapsulating 225Ac.