Silver particles
This is from today's NYTimes:

Sunday, March 10, 2002 10:41 PM

"As Dr. Chou's space travel analogy implies, the potential products at that scale - microscopic electronics, miniature power plants, miracle medicines - seem like science fiction. When engineers venture

into the world of nanoscale dimensions, they enter an alien environment of atomic and molecular forces that can sometimes produce unexpected results. Nucryst, for example, has discovered that nanoscale silver particles not only kill microbes, as silver has long been known to do, but also appear to reduce inflammation"