Nano-materials with traditional materials do not have the bizarre or unusual physical and chemical properties, such as the original conductive copper to a nanometer limit is not conductive, the original insulation silica, crystal, etc., when in a nanoscale boundaries electrical conduction. This is due to nano-materials with small particle size, surface area, surface energy is high, a large proportion of surface atoms, etc., as well as its unique three effects: surface effect, small size effect and macroscopic quantum tunneling effect.
Nowadays, nanoparticles, one of the “building blocks” of nanotechnology are all around us and have been with us throughout our history. Electron micrograph of gold nanoparticles is a snap shot of tiny gold crystals that are 1/10,000th the diameter of a human hair. In every aspect of our day to day lives, from the size of our personal electronic devices to the way diagnose and treat cancer; all part of the promised nanotechnology revolution, nanoparticles may soon transform it. The very word “nanotechnology” seems to suggest something alien; something that belongs far in the future or in the realm of our favorite sci-fi movies.
Gold nanopowders were with us when human beings began making their first tools, and they are present in products we buy at the grocery store every day. They largely flew under the radar until electron microscopes become commonplace several decades ago, but now, the more we turn our microscopes on everyday objects, the more nanoparticles we seem to find.
Even the most seemingly mundane objects can give rise to nanoparticles; detecting them is simply a matter of being able to look closely enough to see them (no simple matter for such small materials). You could find nanoparticles in your jewelry box or the drawer with your family’s fanciest silverware.
I got to see this first hand while I was working in the Hutchison lab at the University of Oregon several years ago.1 Some of my colleagues were trying to understand why silver nanoparticles change size and shape so rapidly, even when they are just left in storage on the shelf. Because they saw such rapid changes in the size and shape of silver nanoparticles, they thought to look and see if large every day pieces of silver and copper (Sterling silver forks, earrings, and wires) might give off nanoparticles.2 To test this, they simply left the fork (or any of the other items) on an electron microscopy grid for several hours, then took the fork away, and had a peek at what it had left behind. Surprisingly, they found that the silver and copper items had left silver and copper nanoparticles behind all over the grid; a most elegant demonstration that human beings can come into contact with a variety of nanoparticles, even in our own homes. Forks and earrings are merely the tip of the iceberg, though. Wherever we go during our day-to-day routine we can encounter nanoparticles (both synthetic and natural).
Synthetic nanoparticles (sometimes called anthropogenic nanoparticles) fall into two general categories: “incidental” and “engineered” nanoparticles. Incidental nanoparticles are the byproducts of human activities, generally have poorly controlled sizes and shapes, and may be made of a hodge-podge of different elements. Many of the processes that generate incidental nanoparticles are common every day activities: running diesel engines, large-scale mining, and even starting a fire.
Engineered nanoparticles on the other hand, have been specifically designed and deliberately synthesized by human beings. Not surprisingly, they have very precisely controlled sizes, shapes, and compositions. They may even contain “layers” with different chemical compositions(e.g. a core made out of gold, covered in a shell of silica, and coated with specifically chosen antibodies). Although engineered nanoparticles get more sophisticated with each passing year, simple engineered nanoparticles can be created by relatively simple chemical reactions that have been within the scope of chemists and alchemists for many centuries. This means that long before people could “see” a nanoparticle through an electron microscope, human beings were both deliberately and accidentally generating a wide variety of these materials.
Related reading: Copper Oxide Nanoparticles silicon dioxide nanoparticles