Radium-doped BaSO₄ Nanoparticles for Future Targeted Alpha Therapy

Targeted alpha therapy (TAT) is continually focused and discussed in radiopharmaceutical research [1]. By the combination of an alpha emitting radionuclide with a biological targeting unit, tumor cells can be affected very efficiently by inducing a high number of double strand breaks to the DNA. 223Ra and 224Ra are two alpha-emitting radionuclides with suitable half-lives for TAT. 223Ra in form of [223Ra]RaCl2 (Xofigo®) is the only EMA- and FDA-approved alpha-emitting radiopharmaceutical as well as the prime example for the working principle of TAT. Based on its calcimimetic behavior, radium is built into the bone structure. To exploit the therapeutic potential of alpha emitters like ²²³Ra and ²²⁴Ra, novel targeting strategies and carrier systems have to be developed. Therefore, it is worth to examine alternative carriers like nanoparticles, using the principle of co-precipitation of Ra/BaSO₄. By the combination of a therapeutic alpha-emitting radionuclide like ²²³Ra on the one hand and the diagnostically applicable barium radioisotope ¹³¹Ba on the other hand with nearly identical physical half-lives it is also possible pursue theragnostic approaches. Thus, our research aims at developing a simple method for the synthesis of small radiolabeled Ra/BaSO₄ nanoparticles and testing further surface functionalization regarding the ability of constructing biological targeting moieties.