Light bright: Nanoparticles emit unique wavelengths of light when struck by a common source of radiation. These waves can be detected as different colors by clinical scanners.
Nanoparticles — tiny objects less than one one-thousandth the width of a human hair — are an increasingly common part of medical treatment and diagnosis. They can be packed with drugs to deliver a cancer-fighting punch or labeled with radioactive tracers that light up on scans. They’re generally thought of as inert, more a transportation vehicle than an active driver. But a new study from researchers at the Sloan Kettering Institute challenges that view.
“We thought nanoparticles were silent carriers for radiation,” says Jan Grimm, a physician-scientist in the Molecular Pharmacology Program at SKI. “But it turns out they speak loud and clear. They emit different signals that can be used for advanced diagnostics, and can even influence your study results.”
These newly recognized signals are the result of energetic interactions between the nanoparticles and radiation emitted from a radioactive atom. When zapped with radiation, the nanoparticles release light or X-rays that can be detected with an imaging technology such as PET or CT.
According to Dr. Grimm, these signals could be used to improve theranostics, a medical approach that merges diagnostic and therapeutic capabilities. “We can now much better see therapeutic tracers that could otherwise not be visualized,” he says.
The new study is the first comprehensive analysis of the interaction of nanoparticles with isotopes emitting radiation of different kinds.
With the discovery of these new signals comes the potential for more versatile types of imaging technology.
“Through exploring how nanoparticles produce light, we found new radioactive tracers that could be used for imaging,” says Chuck Pratt, a Weill Cornell Medicine graduate student working in Dr. Grimm’s lab. Mr. Pratt and Hunter College graduate student Travis Shaffer are co-first authors on the new paper. “That enabled us to develop a new multi-color imaging modality that could enable scientists and clinicians to detect several signals at once instead of one at a time.”
Besides the potential clinical applications, the study also extends scientists’ basic knowledge about the electromagnetic spectrum, which includes light, X-rays, and radio waves. The results, Dr. Grimm says, “have wide implications for anyone working with nanoparticles or radiation anywhere.”
The paper appears today in the journal Nature Nanotechnology.
