| Diagnosing
cancer: |
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| Using the
Power of Gold Against Cancer by Abby Vogel |
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A precious metal long used for jewelry, gold may soon be considered precious for cancer detection and treatment.
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“Once you cut the size of gold down to a few nanometers, its properties change and it reacts with other elements, catalyzes reactions and interacts with light, which makes it valuable for medical applications,” says Mostafa El-Sayed, the Julius Brown Chair and Regents’ Professor in the Georgia Tech School of Chemistry and Biochemistry.
While his wife was fighting breast cancer – a battle she ultimately lost – El-Sayed began reading journal articles about cancer research and realized that the properties of gold might make it useful for detecting and killing cancer cells. To investigate the possibility, he began collaborating with his son, Ivan El-Sayed, a head and neck cancer surgeon at the University of California, San Francisco.
Mostafa El-Sayed designed nanometer-sized spheres of gold and attached them to antibodies targeting specific receptors on cancer cells, which were provided by his son. Using dark-field imaging, they were able to detect the cancer cells to which the antibodies had attached. They could see the cancer cell surfaces and distinguish them from healthy cells due to the strong scattering of light from the gold nanoparticles.
Then the father-son team observed that these metal nanoparticles could also act as light-activated heaters for killing cancer cells. By shining visible laser light on cells, they were able to selectively destroy cancer cells with much lower power than was required to kill healthy cells.
“During these experiments, we realized that gold nanoparticles have advantages over other nanostructures because they can achieve both diagnostics and therapy simultaneously,” notes Mostafa El-Sayed.
After seeing the clinical potential of gold nanospheres on cells, the researchers conducted mouse experiments in collaboration with John McDonald, associate dean for biology program development at Georgia Tech, and Erin Dickerson, formerly a research scientist in McDonald’s laboratory. Xiaohua Huang, a postdoctoral fellow at Georgia Tech and Emory University, and graduate student Erik Dreaden also contributed to this research.
By changing the shape of the nanospheres to cylindrical gold nanorods, the researchers were able to use near-infrared laser light to detect malignant tumors hidden more deeply under the skin and selectively destroy them without harming the healthy cells. Currently, research is being conducted to investigate the effects of gold nanoparticles on animals to clear the way for human clinical trials.
“The unique ability to tune the gold nanoparticle properties by varying their size, shape, composition and medium has allowed us to design nanostructures geared for specific bio-applications,” explains Mostafa El-Sayed.
“Since light converted into heat selectively kills cancer cells, this treatment can be used for different kinds of cancers, avoids normal drug resistance and does not require invasive surgery, thus avoiding post surgery infections.”
This work was funded by grant number DE-FG02-97ER14799 from the U.S. Department of Energy (DOE). The content is solely the responsibility of the principal investigator and does not necessarily represent the official view of the DOE or the United States Government. Significant funding to support this research was also provided by the Julius Brown endowment to Georgia Tech.
Contact: Mostafa El-Sayed (404-894-0292); E-mail: (mostafa.el-sayed <at> chemistry.gatech.edu).
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Last updated: November
14, 2009