Monday, August 08, 2005

Nanomedicine vs Cancer

Nanotechnology used to target, kill harmful cancer cells
Dai and his team shine a very thin laser beam of near-infrared light on something called a carbon nanotube.

The electrons in the nanotube - a hollow tube, resembling straw, made of interwoven carbon atoms about one-100,000th the diameter of a human hair - become excited by the light and release energy in the form of heat.

The heat is so extreme that it is deadly to cells.

To test this approach as a therapy, Dai placed the carbon nanotubes inside a collection of cancer cells, then shone the three-centimeter laser beam on them. The cancer cells were destroyed.

``They were literally cooked to death,'' Dai said. ``The tube acts like a tiny heater.''

But cells without the carbon nanotubes showed no ill effects - the light passes harmlessly through them.

One of Dai's big challenges was to find a way to deliver the nanotubes to sick cells.

He knew that cancer cells have specific receptors. So his team coated the nanotubes with a certain kind of molecule, called folate, which latches onto folate receptors.

This strategy succeeded in delivering the folate-coated nanotubes inside cancer cells, bypassing the normal cells - like Trojan horses crossing the enemy line.
MIT engineers an anti-cancer smart bomb
The team loaded the outer membrane of the nanocell with an anti-angiogenic drug and the inner balloon with chemotherapy agents. A "stealth" surface chemistry allows the nanocells to evade the immune system, while their size (200 nanometers) makes them preferentially taken into the tumor. They are small enough to pass through tumor vessels, but too large for the pores of normal vessels.

Once the nanocell is inside the tumor, its outer membrane disintegrates, rapidly deploying the anti-angiogenic drug. The blood vessels feeding the tumor then collapse, trapping the loaded nanoparticle in the tumor, where it slowly releases the chemotherapy.