Radiation able to be securely stored in nontoxic molecule, study finds

Researchers have discovered that microscopic "bubbles" developed at Kansas State University are safe and effective storage lockers for harmful isotopes that emit ionizing radiation for treating tumors.

The findings can benefit patient health and advance radiation therapy used to treat cancer and other diseases, said John M. Tomich, a professor of biochemistry and molecular biophysics who is affiliated with the university's Johnson Cancer Research Center.

The study looks at the ability of nontoxic molecules to store and deliver potentially harmful alpha emitting radioisotopes—one of the most effective forms of radiation therapy. In 2012, Tomich and his research lab team combined two related sequences of amino acids to form a very small, hollow nanocapsule similar to a bubble.

"We found that the two sequences come together to form a thin membrane that assembled into little spheres, which we call capsules," Tomich said. "While other vesicles have been created from lipids, most are much less stable and break down. Ours are like stones, though. They're incredibly stable and are not destroyed by cells in the body."

The ability of the capsules to stay intact with the isotope inside and remain undetected by the body's clearance systems prompted Tomich to investigate using the capsules as unbreakable storage containers that can be used for biomedical research, particularly in radiation therapies.

"The problem with current alpha-particle radiation therapies used to treat cancer is that they lead to the release of nontargeted radioactive daughter ions into the body," Tomich said. "Radioactive atoms break down to form new atoms, called daughter ions, with the release of some form of energy or energetic particles. Alpha emitters give off an energetic particle that comes off at nearly the speed of light."