Kanazawa, Japan (UroToday.com) There is a substantial problem with binding the radioisotope to a molecular structure. Isotopes like Ra223 and Ac225 have decay chains that emit a total of four alphas. When the first decay occurs, the recoil of the daughter nucleus is sometimes sufficient to break the molecular bond holding the radioisotope. For the isotopes above, one of the daughter nuclei has a long enough half-life to travel through the body. This is doubly bad since not only is the alpha lost to the tumor site but the free isotope may damage healthy organs, especially the liver and kidneys.
The solution to these problems is to capture the radioisotope within a mechanical structure of a size (10’s of nanometers) and composition that alpha particles can escape but the daughter is retained. Either a coating or the composition of the nanocarrier is such that it can still be attached to antibody that targets the tumor. Read more.