Prof. Angela M. Belcher says that colonoscopy — the most sensitive test for the second-most deadly cancer in the United States — may not detect all polyps and cancers. Imagine, instead, screening for colon cancer by shining a light through a scope to illuminate suspect cells that glowed in different colors to signal different abnormalities or stages of disease.
That’s the futuristic device that Belcher, Germeshausen Professor of Materials Science and Engineering and Biological Engineering, is developing with an interdisciplinary team of colleagues at MIT and Massachusetts General Hospital. Belcher is one of a dozen researchers — eight at MIT — who make up the MIT-Harvard Center of Cancer Nanotechnology Excellence. In 2005, the National Cancer Institute chose MIT and Harvard to share one of seven national, multi-institutional hubs aimed at rapidly advancing the application of nanotechnologies to cancer research.
Nanotechnology, the development and engineering of devices so small that they are measured on a molecular scale, is on the brink of playing a significant role in cancer research and treatment.
“One of the problems of early colon cancer detection is that early-stage polyps are sometimes flat and you wouldn’t see them” with traditional methods, Belcher says. “We’re developing a way of fluorescently labeling them so we can look at them with light. They would pop out because they would fluoresce in color.
“We’re also looking at how we can figure out what stage cancer we’re seeing by having different peptide recognition sequences bind to different colon cancer cells. Cells from different stages or types of cancer would fluoresce different colors, so we could follow the progression of the disease,” she says.
BELCHER AND BAWENDI
Belcher and MIT chemistry professor Moungi G. Bawendi are developing new classes of semiconducting nanocrystals — crystalline nanoparticles with powerful electrical properties — that will function as highly efficient, stable, biologically compatible tags.
“In essence, this project will create a toolbox of highly novel, inorganic nanomaterials for a variety of imaging techniques,” says Belcher, a MacArthur Foundation “genius” grant recipient who was last year named Research Leader of the Year by Scientific American.
Using biologically inert building blocks such as gallium nitride and indium gallium nitride — semiconductor materials used as the light-emitting layer in modern blue and green LEDs — Belcher and Bawendi have developed novel nanocrystal materials that appear promising for biological applications.
Belcher piggy-backs fluorescent and magnetic nanocrystal markers onto non-living viruses to create “smart” nanocrystal sensors. “We can build the viruses with genetic material to have any kind of marker we want them to have,” she says. Using sequences of peptides, or protein fragments, as a map, the viruses would bind to certain kinds of cells. A magnetic marker could then be imaged with an MRI. A fluorescent marker would glow in certain kinds of light.
Next steps include testing the safety of the newly developed nanomaterials in cell culture and in animal models.
Belcher uses “nature to create machinery,” as Scientific American put it. She exploits the natural process of self-assembly of a virus called M13. Belcher genetically programs the virus to incorporate within itself nonbiological materials — such as metals and silicon — that it wouldn’t normally use. (As Belcher puts it, it simply hadn’t had the opportunity.) The resulting hybrid is not alive, although it has organic components that can interact with living organisms.
Belcher points to abalone shells as an example of a self-assembling system. “Around 500 million years ago, organisms challenged by changing ocean environments started making hard materials, because all of a sudden, they had the opportunity,” she said. “Male and female abalone make millions and millions of baby abalone and build beautiful materials. They don’t use any toxic materials and they don’t add toxic materials back to their environment.”
If we’re all “examples of self-assembling, self-correcting systems,” she says, it’s not so far-fetched to think of such systems being put to technology’s use. In this case, the technology may be a life-saver.