Not on the market right now, but once they are treatments that use tools like this could be used to pinpoint toxic drugs directly into a tumor without damaging the surrounding healthy tissue. I suppose that they could also be designed to stay closed until enough of a certain chemical is present in the blood stream or tissues. Think of how that could help an athlete – just as they are starting to cramp up after a very strenuous activity the nano tubes detect the fatigue poisons and open up releasing their payload of refreshing drugs.
The nanotubes are “smart” because they can open or close at the ends, depending on how the researchers manipulate the electric charge on the two components. So in principle, a nanotube could encapsulate a drug or a gene, and then open on command to deliver the cargo where it would have the best effect.