Caught in the actinium: New research could help design better cancer treatments
The element actinium was first discovered at the turn of the 20th century, but even now, nearly 125 years later, researchers still don't have a good grasp on the metal's chemistry. That's because actinium is only available ...
In a study led by the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), researchers grew crystals containing actinium and studied the compound's atomic structure. While elements often behave similarly to their lighter cousins on the periodic table, researchers were surprised to find that the actinium behaved differently than predicted by looking at its counterpart, lanthanum.
"There's a breadth of applications for these elements, from nuclear energy to medicine to national security, but if we don't know how they behave, that inhibits the progress we can make," said Jen Wacker, first author of the paper published in Nature Communications and a chemist at Berkeley Lab.
"We're seeing that this work is necessary to really understand the complexity of these radioactive elements, because in a lot of cases, using their surrogates is not sufficient to understand their chemistry."
One area of interest is in using an isotope of actinium (actinium-225) in a cancer treatment method called targeted alpha therapy (TAT), which has shown promise in clinical trials. The TAT method uses biological delivery systems such as peptides or antibodies to move the radioactive element to the cancer site.
When the actinium decays, it releases energetic particles that travel a short distance, destroying the nearby cancer cells but sparing healthy tissue further away.
Researchers grew crystals of a pure actinium compound, seen here through a microscope, to understand how actinium binds to other molecules in a solid. Credit: Jen Wacker/Berkeley Lab
This rendering shows the structure of how actinium (magenta) binds with other molecules. Red triangles point out how the arrangement differs from actinium's lighter counterpart, lanthanum (gray). The stick structure of the binding molecule (the ligand) is surrounded by pockets in the protein. Credit: Jen Wacker/Berkeley Lab