Gold Nanobeacons Detect Sentinel Lymph Nodes

Mar 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: Nanocontainers for nanocargo: Delivering genes and proteins for cellular imaging, genetic medicine and cancer therapy

add to favorites email to friend print save as pdf

Related Stories

Nanoparticles Detect and Purge Metastases in Lymph Nodes

Oct 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. ...

Golden Nanotubes Detect Tumor Cells, Map Sentinel Lymph Nodes

Sep 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 ...

Recommended for you

Twisted graphene chills out

5 hours ago

(Phys.org) —When two sheets of graphene are stacked in a special way, it is possible to cool down the graphene with a laser instead of heating it up, University of Manchester researchers have shown.

Researchers use liquid inks to create better solar cells

5 hours ago

(Phys.org) —The basic function of solar cells is to harvest sunlight and turn it into electricity. Thus, it is critically important that the film that collects the light on the surface of the cell is designed ...

User comments : 0