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August 31, 2009

Neon Cancer Detector

A San Diego researcher has developed a way to tag cancer cells for early detection in the blood stream

Professor Michael Sailor hopes to dramatically change how cancer is treated. He is on a quest to create nanoparticles that travel the bloodstream, latch onto cancers in their earliest stages and destroy them. Sailor's project is staging the war on cancer at the nano-level. The armed forces he is amassing are a thousand times smaller than the diameter of a human hair.

Sailor, a professor of chemistry and biochemistry at the University of California, San Diego (UCSD) has spent years in search of the right stuff--a material safe enough to enter and travel the bloodstream to conquer cancers. The mission: to arm nanoparticles with potent and deadly drugs, inject the particles into the bloodstream and send them on a 'seek and destroy' mission against developing cancers.

"Ideally, you'd like to find the tumor when it's just at the one-cell level, a single cell of the cancerous tumor that's just starting to form," says Sailor. "We can't do that now, but one of the really long-term goals of nanotechnology is to be able to do that."

Tumors that glow fluorescent orange

What Sailor and his team have been able to do is find a safe material, shrink it down to nano proportions and inject it into the bloodstream of mice. "We can actually image and see the tumor glowing orange after we've injected these particles into the animal." The fluorescent orange color helps researchers find the cancer earlier than an MRI or X-ray would detect it.

The material chosen for this nano army is silicon, the same material used to make computer chips. "One of the reasons we work with silicon materials is that silicon can degrade in the body to harmless byproducts," explains Sailor. "We want to make a nanostructure that will go into the body, do whatever it has to do and then dissolve away."

"The NSF has been key for my research program," says Sailor. Seventeen years ago when he received funding from the agency, Sailor wasn't thinking about cancer. He was just trying to figure out how to make nanoparticles. "We didn't think about putting them in the body. We just thought, 'oh well, we can take these little silicon chips and break them up and make nanoparticles out of them.' Then about 10 or 12 years later, we started looking into cancer more directly."

Making armies of silicon nanoparticles

What has evolved is a recipe for making specialized nanoparticles. In his lab, he shows how it's done. Using an electrochemical process, Sailor's team chemically drills tiny holes into a silicon wafer; each hole could carry a payload of cancer-fighting drugs. "Those holes are small but they're not so small that you can't load a drug into those pores."

Using industrial strength cleaners, the same ones used to clean jewelry, ultrasonic waves break up the spongy wafer into smaller and smaller pieces. The process lasts at least eight hours--until the spongy pieces are nano-size and small enough to inject into the bloodstream. The particles are also chemically coated to emit a fluorescent glow.

"We want them to get into the body, swim around inside the body, find the tumor and then glow and then allow us to be able to image them."

Today, nanoparticles injected in mice are successfully helping researchers find certain cancers. Sailor hopes in five to 10 years these materials will be proven safe and effective to inject into humans.

"That's one of the goals of nanotechnology--that we can build these vessels that can hold a drug that would normally be very toxic to the body and, in fact, it's very toxic to the tumor, too, and it holds that drug, keeps it from getting out until it finds the tumor, and then it opens up and lets it out."

Staying focused

There are still many challenges but Sailor says the letters he receives from cancer patients, their families and friends help him stay focused on the task.

"They all kind of have the same theme. 'I'm dying of cancer,' 'My wife is dying of cancer,' 'My son is dying of cancer, and we're trying to find a way to keep him from dying. Can you help us?' We're a basic research organization and we are trying to develop the tools that maybe in five to 20 years will be used to treat this problem."

Sailor posts those letters outside his office to remind him and others why the 20 years invested in this project are worth it. If Sailor's efforts pay off, cancer cells could be killed off early, long before they have a chance to spread and need to be treated with surgery or heavy doses of radiation or chemotherapy.

Miles O'Brien, Science Nation Correspondent
Ann Kellan, Science Nation Producer

Any opinions, findings, conclusions or recommendations presented in this material are only those of the presenter grantee/researcher, author, or agency employee; and do not necessarily reflect the views of the National Science Foundation.