Quantum Dots & Cancer
Targeting Cancer with Glowing Quantum Dots
Tiny luminescent particles thousands of times smaller than the diameter of a single hair may hold the power to target cancerous tumors, deliver medicine, and diagnose disease from within the human body with pinpoint accuracy.
Shuming Nie, Director for Nanotechnology and Bioengineering at the Winship Cancer Institute, is working to maximize this power by encapsulating these semiconductor nanoparticles—or "quantum dots"—inside a protective polymer coating. Nie is one of the first scientists in the world to have used nanotechnology for medical applications.
After coming to Emory University in 2002, he and colleagues linked quantum dots to tumor-targeting molecules and found that they accumulate at tumor sites. The probes are twenty times brighter than organic dyes and fluorescent proteins, so they hold great promise for improving imaging diagnostics.
"Quantum dots have interesting optical qualities that make them useful for imaging," says Nie, who is also the Wallace H. Coulter Distinguished Chair in Biomedical Engineering. "They can emit different colors of light depending on the size of the semiconductor particle, from blue to infrared."
In a photo of one of his experiments, a mouse injected with multicolor quantum dots and placed under an ultraviolet light looks as if it has swallowed a string of miniature holiday lights, which trail down its backbone in green, yellow, and red. The probes can detect and track multiple tumor targets, serving as biomarkers—microscopic flags that can let doctors know early in the disease process where the cancer cells are and how they are spreading.
Several years ago, Nie attached quantum dots to antibodies that guided them to prostate tumor sites in living mice, where they clumped together and were visible using a simple mercury lamp. "In addition to imaging, we could also link these particles to therapeutic compounds to deliver medications directly to the site," Nie says.
Targeting specific vulnerabilities, diseased cells, and organs could have applications across a range of treatments, such as improving the delivery of chemotherapy or cardiovascular drugs. Instead of being diffused throughout the body, the drugs could be sent straight to the areas where they are needed—improving effectiveness while decreasing toxicity and side effects.
The tri-block polymer coating, developed by Nie, improves the solubility of quantum dots in water solutions, protects them from the environment, and provides functional groups for bonding to biological molecules.
"Shuming Nie's novel polymer coating enables a new and better formation and manufacturing process for bio-functionalized nanoparticles," says Laura Fritts, case manager at Emory's Office of Technology Transfer. "The new QD's show promise in their ability to overcome the targeting and delivery failures that have stymied therapeutic and diagnostic approaches such as antibody and gene therapies."
The National Cancer Institute has selected Emory and Georgia Tech as one of seven National Centers of Cancer Nanotechnology Excellence. The Emory-Georgia Tech Nanotechnology Center for Personalized and Predictive Oncology will function as a discovery accelerator to integrate nanotechnology into personalized cancer treatments and early detection. Emory and Georgia Tech now have one of the largest federally funded programs in the country in this arena. The grant is expected to reach nearly $20 million over a five-year period.
While human studies of quantum dot tracking and targeting remain in the future, mice studies have proven successful—Nie has packaged the commonly used cancer drug taxol into biodegradable nanospheres engineered to seek out head and neck cancer cells and release their drug contents at the tumor site, delivering a direct hit.
"The fact that the technologies have been licensed to several companies is to say that they are useful," he says. "This is a general platform technology that can have many applications. I'm most excited about quantum dots’ potential in tumor imaging and targeted therapy."
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