Brown University chemist Shouheng Sun is working to develop a way of destroying cancer cells without harming healthy tissue. At right is Chenjie Xu, who is working with him.

The Providence Journal / Bob Thayer

In the future that scientist Shouheng Sun and his student Chenjie Xu are working to create, a person with deadly cancer would not only survive but flourish.

In this future –– perhaps only a decade from now –– doctors would use tiny particles that Sun and Xu have synthesized to deliver cancer-killing drugs directly to the cancer. Healthy cells would be untouched, sparing a patient the terrible side effects that often accompany chemotherapy today. The immune system would be preserved. Hair would remain on the scalp. Patients would not lose weight, become nauseous or experience pain. Treatment would be shortened, normal life more rapidly restored.

This future begins on the third floor of a brick building at Thayer and Waterman streets in Providence. This is Sun’s nanomedicine laboratory, where Sun, a chemistry professor at Brown University, and Xu, a doctoral candidate, test the nanoparticles they produce on live cells. A nanoparticle is a manmade cluster of atoms or molecules measured by nanometer, or one-billionth of a meter (one nanometer is roughly 1/10,000 the diameter of a human hair).

“When you do cancer therapy,” Sun says, “when you use a drug to kill, you really want a drug to kill only tumor cells, not the healthy ones. Now, the problem is: when you do the injection, the drug can be uptaken by both healthy cells and the tumor cells.”

“It’s non-selective,” says Xu.

“No targeting capability. So the drug is very powerful –– but it’s going to kill all cells which have taken up that drug.”

“Also, it’s hard to track the drug. You want to know where the drug goes.”

“Only a small portion of the drug ends up in tumor cell,” Sun says. “That’s why you have to keep adding more and more and more –– in order to kill tumor cells. But you also cause more side effects. You kill more healthy cells.”

The promise of nanomedicine is broad, but Sun’s lab is elementary, as research goes. It includes an incubator to grow test cells, a laminar-flow cabinet providing a clean environment to introduce the nanoparticles into the cells, and a microscope to examine the results.

A microscope, of course, does not allow you to see the tiny thing that Sun and Xu have synthesized: a so-called dumbbell structure in which a gold nanoparticle is attached to an iron-oxide nanoparticle. A common cancer-fighting drug is then attached to the gold particle; an antibody, or “targeting agent,” is attached to the iron-oxide particle. The antibody can detect antigens on the surface of cancerous cells –– antigens that do not exist on healthy cells. When the dumbbell arrives at a cancer cell, it “delivers” the cancer-fighting drugs. Healthy cells are unaffected. It’s a concept that Sun developed at the IBM Thomas J. Watson Research Center, where he worked before coming to Brown, in January 2005.

Sun, who holds advanced degrees from Brown and Nanjing University in China, calls up a diagram of the nanoparticles on his computer. They look like –– well, a dumbbell.

“You have the targeting agent here,” Sun says, pointing to the iron-oxide nanoparticle and the antibody attached to it. “You have the anti-cancer drug over here. This is the ‘vehicle’ –– our version of a Mercedes Benz with a good GPS unit and a special passenger.”

The dumbbell arrangement offers other potential: it could be used to detect cancer at an early stage, before a tumor was visible to the naked eye, for example. In this application, the nanoparticles would find a tiny cluster of cancer cells –– and their location could be confirmed visually, through a microscope, or magnetically, with magnetic-resonance imaging, or MRI, equipment. Surgery, needed today when clusters grow into large tumors, could be avoided.

“If we can identify these cancer cells early enough,” Sun says, “we can kill these cells readily by a drug.”

Sun and Xu’s work, reported recently in the Journal of the American Chemical Society, involved tests on malignant breast-cancer cells. But the technology can be applied to other types of cancer as well.

The next step is studies with mice, which will be undertaken with scientists at the Warren Alpert Medical School of Brown University and Rhode Island Hospital. Human trials could begin in five years, Sun estimates, with clinical use possible within a decade.

“The work at Brown proves that the idea of targeted delivery of medicine for successful cancer therapy may soon be materialized,” Sun says.

With Sun, Xu was the lead author of “Dumbbell-like Au−Fe3O4 Nanoparticles for Target-Specific Platin Delivery,” published online March 10 in the Journal of the American Chemical Society:

http://pubs.acs.org/doi/abs/10.1021/ja900790v?prevSearch=%22chenjie+xu%22&searchHistoryKey=

The Sun Research group at Brown: http://www.chem.brown.edu/research/sun/

Xu is on facebook at http://www.facebook.com/home.php? #/profile.php?id=1012970&v=info&viewas=1012970

Contact information for Xu: http://www.chem.brown.edu/research/sun/group.html

A U.S. government primer on nanotechnology is at http://www.nano.gov/html/facts/faqs.html

G. Wayne Miller welcomes suggestions for future What’s Next stories.

gwmiller@projo.com