Gold Nanobeacons Detect Sentinel Lymph Nodes

March 25, 2010

(PhysOrg.com) -- Virtually every patient diagnosed with breast cancer or melanoma undergoes lymph node biopsy to determine if their cancer has begun spreading in the body. Taking this biopsy involves an invasive and uncomfortable procedure, and though necessary it detects metastases less than 95% of the time. To eliminate the need for invasive biopsy, and to improve upon the diagnostic sensitivity of biopsy, researchers have been working to develop non-invasive imaging techniques to identify tumor-bearing sentinel lymph nodes.

Now, a group of investigators at Washington University of St. Louis, led by Dipanjan Pan, Ph.D., and including Gregory Lanza, M.D., and Samuel Wickline, M.D., both members of the Siteman Center of Cancer Nanotechnology Excellence, has developed "soft" gold nanoparticles that accumulate in and that are visible using a technique known as photoacoustic imaging. The investigators published their results in the journal Biomaterials.

Photoacoustic imaging combines aspects of optical and ultrasound imaging in a sensitive imaging technique suitable for use in the human body. Photoacoustic imaging agents, including gold nanoparticles, emit sound waves when illuminated with specific frequencies of light. In the case of gold nanoparticles, the activating light energy occurs in the near infrared, a region of the optical spectrum that passes readily through biological tissues, and their photoacoustic emissions are strong enough to be detectable using standard clinical ultrasound equipment.

The key to this study was developing a gold nanoparticle imaging agent that balances the rate of accumulation in sentinel lymph nodes with the rate of elimination of particles that the lymph nodes do not trap. The solution was to wrap multiple , each 2-4 in diameter, within a soft polymer matrix, producing a 90 nanometer gold nanobeacon that accumulates rapidly in sentinel lymph nodes. When the investigators injected their nanobeacons into mice and imaged lymph nodes one hour later, they found that the photoacoustic signal was nine-fold stronger in lymph nodes than in surrounding blood vessels. While larger nanoparticles produced a stronger signal, they did not accumulate exclusively in the lymph nodes, so the contrast they produced was much smaller.

This work, which is detailed in a paper titled, "Near infrared photoacoustic detection of sentinel lymph nodes with nanobeacons," was supported in part by the NCI Alliance for Nanotechnology in Cancer, a comprehensive initiative designed to accelerate the application of nanotechnology to the prevention, diagnosis, and treatment of cancer. An abstract of this paper is available at the journal's Web site.

Explore further: Improved imaging for identifying breast cancer in overweight women

Related Stories

Golden Nanotubes Detect Tumor Cells, Map Sentinel Lymph Nodes

September 24, 2009

(PhysOrg.com) -- Biomedical researchers at the University of Arkansas in Fayetteville and the University of Arkansas for Medical Sciences (UAMS) in Little Rock have developed a special contrast-imaging agent made of gold-coated ...

Nanoparticles Detect and Purge Metastases in Lymph Nodes

October 30, 2009

Colonoscopy represents one of the great weapons against cancer. In one step, a physician can find precancerous lesions in the colon and then cut them out, an on-the-spot intervention that prevents cancer from developing. ...

Recommended for you

Meet the high-performance single-molecule diode

July 29, 2015

A team of researchers from Berkeley Lab and Columbia University has passed a major milestone in molecular electronics with the creation of the world's highest-performance single-molecule diode. Working at Berkeley Lab's Molecular ...

Could stronger, tougher paper replace metal?

July 24, 2015

Researchers at the University of Maryland recently discovered that paper made of cellulose fibers is tougher and stronger the smaller the fibers get. For a long time, engineers have sought a material that is both strong (resistant ...

Reshaping the solar spectrum to turn light to electricity

July 28, 2015

When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense. The solar cells—made often of silicon or cadmium telluride—rarely cost more than 20 percent ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.