gabrlknght writes with this excerpt from Science News: "Because nanoparticles are small, a large proportion of their atoms are near the particle's surface. Having fewer neighbors, those relatively unconfined atoms can link in unusual ways, giving materials made of nanoparticles novel properties. But the same characteristic that makes nanostructures useful — size — also makes working with them no small task. Engineering on the nanoscale is like building a ship in a bottle while wearing mittens. It would be far cheaper and easier, researchers agree, if nanoparticles could just arrange themselves into nanomaterials — like dropping the pieces of the ship into the bottle and then sitting back to watch the ship build itself. What scientists are working on now is finding the right chemistry — creating just the right conditions so that natural properties such as charge or magnetism direct the pieces of the ship to come together just so, with the mast above the deck and never below or to the side. This idea, called self-assembly, isn't exactly new. Examples range from the simple separation of oil and vinegar in a bottle of salad dressing to the complex movements of proteins and enzymes — themselves nanosized — reacting in living cells. Scientists have long been inspired by these naturally self-assembling systems. But designing self-assembling systems in the lab, with nanoparticles, presents its own scale of difficulty. And making self-assembled nanomaterials grow large enough to actually be useful is even more challenging."