Gold "nano-bullets" could seek and destroy inoperable human cancers, suggest new studies by US scientists. The tiny silica particles are plated with gold and heat up when near infrared light (NIR) is shone on them. This kills the cancer cells. Tests on human breast cancers, both in the test tube and in tumours in mice, were highly successful, the researchers report in the Proceedings of the National Academy of Sciences. "The nanoshells are designed to absorb near infrared light and convert that light to heat," explains Jennifer West, who led the study at Rice University, Houston, Texas. This is possible because the body's normal tissues are "essentially transparent" to NIR. West says the potential benefits of the treatment should be that, unlike other cancer treatments such as surgery, it would be non-invasive. Both NIR and the nanoshells are completely harmless by themselves, she says. "We believe that we should also be able to treat very small metastases, not detected yet," West told New Scientist. More recent, unpublished work by the group, has shown that the gold bullets can be injected into the blood stream and find their way to cancer cells in mice. "These results are promising, particularly for tumours that cannot be treated by surgery," says Emma Knight, at Cancer Research UK. "However, the studies are at a very early stage." Source New Scientist.