There are lots of interesting possibilities for nano particles
many of which are still theoretical, but more and more practical applications are being found.
One key point of nano particles is that they have a very large surface area to volume ratio,
Chemical reactions only occur at the surface, where the reacting chemicals are in direct contact with each other.
This makes nano particles more reactive than the same material in bulk form.
Also mixing nano particles of different materials and then compressing them together, till they bind, can make new materials with novel properties which would not be achievable by other means.