A new cancer treatment is on its way.

Researchers at Washington University in St. Louis (WUSTL) are to use "gold nanocages", which, when injected, selectively gathers in tumors. When the tumors are later treated with laser light, the nearby tissue is hardly warmed, but kills the wicked cells.

A similar method is being developed at the University of California in Santa Cruz using hollow gold nanospheres and another is in progress at Rice University using gold nanoparticles. Gold salts and gold colloids, a type of mixture in which one substance is scattered equally through another, have been used to treat arthritis for more than 100 years. So, it is believed that the nanocages themselves will be nontoxic.

The nanocages are empty boxes made by precipitating gold or silver nanoparticles.

The scientists covered the nanocages with a layer of PEG that defends against the adsorption of proteins by camouflaging the nanoparticles so that the immune system cannot identify them. In the experiment, the mice were injected with a radioactive tracer integrated in a molecule similar to glucose.

It was found that the tumors of nanocage-injected mice were considerably weaker on the PET scans than those of buffer-injected mice, suggesting that many tumor cells were no longer functioning.

However, the researchers were not satisfied with the results since only 6% of the injected particles gathered at the tumor site. The number should be nearer to 40% so that fewer particles would have to be inserted.

Meanwhile, the scientists at WUSTL have just received US$2,129,873, a five-year allowance from the National Cancer Institute to carry on their work with photothermal therapy.