In
2008, a team of investigators at Stanford University’s Center for
Cancer Nanotechnology Excellence demonstrated that they could use a
technique known as nanoparticle-aided Raman spectroscopy to look at
microscopic structures, including nascent tumors, deep inside the body.
That team has now conducted extensive preclinical tests and shown that
the gold nanoparticles can be safely administered into the colon and
used with a Raman endoscope to image the inside of the large intestines.
Reporting
their work in the journal Small, Sanjiv Sam Gambhir and his colleagues
describe the experiments they conducted using radioactively labeled gold
nanoparticles to track the accumulation of the nanoparticle imaging
agents inside mice. Dr. Gambhir is the principal investigator of the
Stanford Center for Cancer Nanotechnology Excellence, one of nine such
centers included in the National Cancer Institute’s Alliance for
Nanotechnology in Cancer.
After
labeling the nanoparticles with a radioactive isotope of copper, the
investigators used micro-positron emission tomography (micro-PET) to
image the nanoparticles’ location in the body. When the nanoparticles
were injected intravenously, they accumulated in a variety of organs,
with almost 10% of the dose of nanoparticles ending up in the liver. In
contrast, when the nanoparticles were injected rectally into the colon,
less than 1/10th of 1 percent of the nanoparticles accumulated outside
of the large intestine even as far as two weeks after injection. In the
colon, the nanoparticles could be visualized using an endoscope modified
to detect Raman signals.
