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Last Updated: Tuesday, 4 November, 2003, 00:35 GMT
Giving cancer the 'nano-bullet'
lab shot
Nanoparticles could help fight disease
Tiny nanoparticles could be launched into tumours and heated up using light to destroy cancer cells, say doctors.

This could help treat cancers which are inoperable and resistant to chemotherapy, they say.

US researchers, writing in the Proceedings of the National Academy of Sciences, say that experiments on mouse tumours have proved successful.

Cancerous tissue was destroyed and healthy tissue spared using the technique, they say.

The "nanoshells" are developed by a team from Rice University in Houston, Texas, who say that many tumours which are hard to treat by conventional means could be tackled this way one day.

The nanoshells are made from silica coated with gold, which would be injected into a tumour located using a scanner.

A near-infrared wavelength light would then be shone on the area.

This penetrates the skin to reach the tumour, and, at the right frequency, actually causes the particles to heat up.

Enough heat is generated to damage the cancer cells and hopefully restrict the growth of the tumour.

However, surrounding cells would hopefully be spared.

Early research

The work is at an early stage, but animal experiments have encouraged the researchers.

Tumours in the animals were injected with the nanoshells, and within four to six minutes the near-infrared light heated them up sufficiently to kill the cancer cells.

The team suggested that, in time, the technique could have a "large impact" on treatment.

Other researchers in the field say that the it is possible to make particles far smaller than those used in the Rice University experiments.

Their "nanoshells" are approximately 110 nanometres across - one nanometre is a billionth of a metre.

Researchers elsewhere have made particles as small as one nanometre.


They believe it is possible to produce nanoparticles that "assemble themselves" using the same ingredients, but which could then be injected into the bloodstream to find their own way to tumours or be directed there using magnets.

These particles would behave like a "magnetic fluid".

Professor Thomas Rademacher, from University College London, and a member of the London Centre for Nanotechnology, told BBC News Online: "The particles they have used there are very large - they could never be injected into the bloodstream.

"These researchers are trying to prove in principle that you can heat them up using light."

He said: "There are so many potential applications for this technology, because, with the self-assembling nanoparticles, they could be constructed with gold, or iron, allowing us to heat them up, and to guide them around the body."

A recent study published in the New England Journal of Medicine demonstrated how nanoparticles could seek out and enter cancer cells spread around the body, simply by adding a sugar which is taken up by prostate tumour cells.

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