While colloidal gold has been used to safely treat people with rheumatoid arthritis for several decades, the toxicity of quantum dots, which contain the heavy metal cadmium, and their long-term fate in the body are still being studied, Dr. Nie notes.
Compared with quantum dots, the gold particles are more than 200 times brighter on a particle-to-particle basis, although they are about 60 times larger by volume. Covered with a non-toxic polymer, the gold particles are about 60-80 nanometers in diameter. That's 150 times smaller than a typical human cell and thousands of times smaller than a human hair.
"I expect that with these probes, it will be possible to detect cancer much earlier, at the microscopic level," says Dong Moon Shin, MD, associate director of Emory's Winship Cancer Institute and professor of hematology, oncology and otolaryngology. Dr. Shin's laboratory is working with Dr. Nie's to refine the gold particles' use in living animals.
"Even a half-centimeter-wide nodule contains millions of cancer cells, but with this technology we can detect many fewer cells at a time," says Dr. Shin.
In the Nature Biotechnology study, the researchers report that they are able to detect human cancer cells injected into a mouse at a depth of 1-2 centimeters. That makes the gold particles especially appropriate tools for gathering information about head or neck tumors, which tend to be more accessible, Dr. Shin says. The technology will need further adaptation for use with abdominal or lung cancers deep within the body.
The particles described in the study were linked with "single chain variable fragment" (ScFv) antibodies that recognize epidermal growth factor receptor, which is present on the surfaces
|Contact: Vince Dollard|