nanoparticle

noun

1. Any microscopic particle less than about 100 nanometers (nm) in diameter.

   “Nanoparticles of various sorts are already found in products like sunscreen, paint and inkjet paper. More exotic varieties offer promise in medicine for sensitive diagnostic tests and novel treatments: the detection of Alzheimer's disease by finding a protein in spinal fluid, for instance, or nanoparticles that heat up and kill cancer cells.”

   “The high surface area of a nanoparticle relative to its weight and volume makes it behave differently from larger masses of the same material.”