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April 4, 2013 Volume 34, No. 25

Scientists harness alpha particles for radiation cancer therapy


The design of a gold-plated nanoparticle is breakthrough in radiation treatment

It is not wise to use a cannon to kill a mosquito,” the old saying goes. 

But what if you could focus the cannon’s power on a concentrated tiny space? 

In a new study, University of Missouri researchers have demonstrated the ability to harness powerful radioactive particles and direct them toward small cancer tumors while doing negligible damage to healthy organs and tissues. The study was published in February in the journal PLoS ONE.

Typically, when radiation treatment is recommended for cancer patients, doctors are able to choose from several radiopharmaceuticals that use low-energy radiation particles, known as beta particles. 

But for years, scientists have been studying how to in cancer treatments alpha particles, which are radioactive and contain a large amount of energy.

The challenges to using alpha particles, which are more than 7,000 times heavier than beta particles, include confining alpha in a designated location inside the body while preventing radiation from wandering to healthy organs and tissues.

“We believe we have found a solution that will allow us to target alpha particles to other cancer sites in the body in an effective manner,” said David Robertson, director of research at the MU Research Reactor and professor of chemistry in the College of Arts and Science.

Robertson and researchers from Oak Ridge National Laboratory and the School of Medicine at the University of Tennessee in Knoxville used the element actinium, known as an “alpha emitter” because it produces alpha particles. 

As it decays, actinium creates three additional elements that produce alpha particles. 

Due to the strength of these particles, though, keeping the elements concentrated on the cancer was impossible until Robertson and Mark McLaughlin, MU doctoral student and co-author on the study, designed a gold-plated nanoparticle that serves as a holding cell for the elements.

Robertson’s nanoparticle is a layered device. At the core is the original element, actinium. Robertson’s team then added four layers of material and coated the nanoparticle with gold. This made the nanoparticle strong enough to hold the actinium – and the other alpha emitters that were created – long enough for any alpha particles to destroy nearby cancer cells.

“Holding these alpha emitters in place is a technical challenge that researchers have been trying to overcome for 15 years,” Robertson said. “With our nanoparticle design, we are able to keep more than 80 percent of the element inside the nanoparticle 24 hours after it is created.”

Though alpha particles are extremely powerful, they don’t travel very far. When the nanoparticles get close to cancer cells, the alpha particles move out and destroy the cell much more effectively than current radiation therapy options, Robertson said.

— Nathan Hurst