Nano Worms Fish for Tumors

Treatments for cancer typically involve a shock and awe approach: use drugs to wipe out all cells, including the healthy ones, with hopes of killing off the cancerous ones.

But researchers are constantly looking for ways to target just the diseased tissue and leave the healthy stuff intact. One approach involves nanoworms, tiny particles of iron oxide joined together in a long, squirmy chain. The worms carry molecules that hone in on tumors. Once attached to the tumor, the iron particles make it easy for doctors to spot the cancerous zone using an MRI machine.

A special polymer coating helps the worms evade the body's immune system, which might otherwise destroy the tumor killer before it reached its target. This last bit about evading the body's immune system is particularly intriguing to me, because it seems like it could be a double-edged sword. You need to be able to sneak the particle in for it to do any good, but then once it's in the body, could it ultimately do more harm than good?

According to team member Geoffrey von Maltzahn of MIT, researchers try to optimize such particles so that they circulate in the blood stream just long enough to find the tumor and then degrade without forming toxic byproducts.

"It is possible to do both so that these things stay in the right places for a long time, but then aren't kept around indefinitely," said von Maltzahn.

With these particular nanoworms, the long shape helps them circulate in the blood for a long time. But in time, cells from the body's immune system will eventually find the particle and devour it. And the iron core will slowly dissolve, releasing iron that the body can use as a supplement.

"That is an advantage of iron oxide particles over other nanoparticle formulations that are either non-degradable (carbon nanotubes) or give off toxic byproducts (quantum dots: cadmium ions)," said von Maltzahn.

 

Image: Ji-Ho Park, UCSD