Tiny gold-centered balls are currently used to spot counterfeit money, and a new mouse study shows that they can also safely detect cancer.
Most colorectal cancers begin as small, slowly developing lumps of abnormal tissue. These polyps line the intestine or rectum.
Doctors see larger polyps with an endoscopy – which uses a tiny camera at the end of the tube – but tiny, flat, or obscure ones are often missed, along with the opportunity to catch abnormal tissue early on.
When scanned for authenticity, these gold-silica nanoparticles (pictured) embedded into currencies scatter light in unique patterns called Raman spectra.
About 100 nanometers in diameter, they can also have little hook-shaped peptides that home in and latch onto cancer cells. Free-floating nanoparticles typically just wash away. So during an endoscopy, doctors can better spot cancers by looking for places where these gold-silica nanoparticles have stuck.
“Photoimaging with these nanoparticles holds the promise of very early disease detection, even before any gross anatomical changes show up, without physically removing any tissue from the patient,” says study leader Sanjiv Gambhir of Stanford University.
According to a Stanford release:
Typically, light bounces off of a material’s surface at the same wavelength it had when it hit the surface. But in each of the specialized materials, about one ten-millionth of the incoming light bounces back in a pattern of discrete wavelengths characteristic of that material. The underlying gold cores have been roughed up in a manner that greatly amplifies this so-called ‘Raman effect,’ allowing the simultaneous detection of many different imaging materials by a sensitive instrument called a Raman microscope.
The team shows that these nanoparticles are safe for use in mice by monitoring them for various changes, such as in weight, behavior, blood count, inflammation, and gene expression.
- They found that injecting the particles into veins caused them to seep into the liver, spleen, and bone marrow; but they stay put when placed directly into the intestines (until excreted, that is).
“These nanoparticles’ lack of toxicity in mice is a good sign that they’ll behave well in humans,” Gambhir says.
They’re filing for FDA approval to proceed to clinical studies. Eventually, patients may be able to simply drink the nanoparticles. The tiny gold balls will settle in the stomach, travel to the bowel, and latch onto cancer cells, allowing for real-time detection and diagnosis during an endoscopy.
The study was published in Science Translational Medicine yesterday.