Nanotechnology

 NANOTECHNOLOGY

The pure gold in a wedding band creates a symbol of permanence and stability. But medieval artisans knew that mixing super-small amounts of glass with gold could create different colors and effects. Their work is considered a primitive application of nanotechnology-the art of manipulating matter a few atoms at a time. Nanotechnology works on an almost unimaginably small dimension, using the nanometer, a billionth of a meter, as a basic measurement. Substances often act differently on an atomic scale than they do in larger quantities, when fewer atoms are at the surface of the overall structure and the forces of Newtonian physics come to dominate. At the atomic level, magnetic and other properties can be exaggerated, bonds among atoms are stronger, and catalytic reactions become more dynamic. Nanotechnologists precisely engi neer small groups of atoms and then assemble those groups into larger structures. They foresee the treatment of tumors or genetic malignancies with "molecular machines'' that rootout bad cells or viral DNA sequences. Researchers at MIT found that after severing the optic nerve of hamsters. an injection of nanoparticle peptides created a scaffold that allowed the severed nerve to regenerate and sight to be recovered. Already, filters made with nanoscale particles are being used to purify drinking water. The techniques used to manipulate materials at the nanoscale are not that different, conceptually, from those involved in everyday manufacturing. Advances in microprocessor production, the creation of thousands of circuits on silicon wafers through optical lithography, or etching with light already allows engineers to work at a scale of less than 100 nanometers. It may allow even smaller scale work if more intense light or x-rays are used. Other nanotechniques rely on small-scale chemical or physical processes to let material build up an atom at a time. The way materials attract or repel each other at the atomic scale perhaps in the presence of a magnet or an electric current allows researchers to grow carbon nanotubes, for example, or quantum dots, which may prove useful in a variety of applications. According to the National Nanotechnology Initiative, more than 800 products incorporate nanotechnology in some way, and rapidly advancing technology suggests that number will only increase.