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Biodegradable Nano-Particles Could Help Find Tumors, Deliver Drugs Safely

A team of researchers at the University of California San Diego reports it has developed a new non-toxic nano-material that may help doctors diagnose diseased tumors more effectively and deliver drugs more safely.

While the microscopically small-scale materials known as nano-particles have been tested in laboratory animals, University of California San Diego chemistry professor Michael Sailor says most materials are too toxic to be used in people.

"But they do prove the principle, and allows us to say, 'Hey, there is something good about this material,'" he says. "It could be more effective at targeting a tumor in the body or more effective in treating a cancer or treating a drug to a certain disease tissue site."

Sailor describes his work in a new study published in the journal Nature Materials.

The research team used a nano-machining technique to break down pure silicon wafers - like those used to make computer chips - into miniscule silicon flakes 50 times thinner than a human hair.

"After preparing these nano-materials, we process them with a separate chemical step. This electrical chemical process also alters the structure of the material so that it glows under ultraviolet light."

That glow can reveal tumors too tiny to detect by other means or allow a surgeon to be sure all cancerous growth has been removed. Sailor and colleagues tested the material by injecting it into mice with diseased tissues.

"And the particles circulated through the bodies and eventually circulated into the tumors of the mice, and there we could see the tumors light up with the glow of the fluorescent nano-particles."

The tumors glowed for several hours and then dimmed as the particles broke down. Levels dropped noticeably in a week and were undetectable after four weeks. Such targeted therapy may allow doctors to use smaller doses of a drug and so reduce potentially toxic side effects. This was the first study to image tumors and organs using biodegradable silicon nano-particles in live animals.