Cancer therapy that involves injecting radioactive particles into tumor sites is a tried but not quite true method. One problem is delivering sufficient energy to diseased tissue without hurting the rest of the body too much. This is why radiopharmaceuticals that emit beta radiation (electrons) have been used. Alpha radiation emitting (2 protons + 2 neutrons) radionuclides have such comparatively enormous energy that they need to be carefully contained so as to not cause more harm than good, which has been difficult to accomplish.
Now researchers from University of Missouri and Oak Ridge National Laboratory are reporting the development of gold coated lanthanide phosphate nanoparticles that effectively contain actinium, an alpha decaying element. These nanoparticles can be injected to tumor sites with much more confidence that the energy of the radioactive cores will be delivered to target.
From the study abstract in PLOS ONE:
The major challenge with α-generator radiotherapies is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-target tissue. The recoil energy of the 225Ac daughters following α decay will sever any metal-ligand bond used to form the bioconjugate. This work demonstrates that an engineered multilayered nanoparticle-antibody conjugate can deliver multiple α radiations and contain the decay daughters of 225Ac while targeting biologically relevant receptors in a female BALB/c mouse model. These multi-shell nanoparticles combine the radiation resistance of lanthanide phosphate to contain 225Ac and its radioactive decay daughters, the magnetic properties of gadolinium phosphate for easy separation, and established gold chemistry for attachment of targeting moieties.