3 hours ago by Renee Cho, Earth Institute, Columbia University Computer-rendered view inside a carbon nanotube. Credit: Geoff Hutchison

Scientists at Northwestern University have found a way to detect metastatic breast cancer by arranging strands of DNA into spherical shapes and using them to cover a tiny particle of gold, creating a "nano-flare" that lights up only when it finds breast cancer cells. At MIT, researchers are trying to boost the photosynthetic capacity of plants by embedding tiny tubes of carbon called nanotubes into chloroplasts. They hope to eventually develop plants with the ability to monitor environmental pollution, pesticides, fungal infections, or exposure to bacterial toxins. These are just two instances of ongoing research in nanotechnology, one of the fastest growing areas of science, engineering and industry that is used in more and more consumer products each day.

Nanotechnology encompasses the production and manipulation of materials on a tiny scale measured in billionths of a meter, or nanometers. It sometimes involves layers of material just a single atom thick about 0.2 nanometers. By comparison, a human hair is 80,000 nanometers; a DNA molecule is 22.5 nm.

Nanoparticles do exist in naturein dust, forest fires, volcanoes, metals, etc. But nanotechnology generally involves engineered materials (which can include natural nanoparticles) with at least one dimension measuring 100 nm or less. At the nanoscale, the classic laws of physics no longer apply, resulting in material taking on different optical, electrical or magnetic properties than it would have in a bulkier form. This is partly because material at the nanoscale has a relatively larger surface area vis vis its volume than the same material in bulk form.

It is because nanomaterials have these altered properties that they are so useful. They can have increased capacity to conduct or resist electricity, excellent color purity, enhanced heat storage or transference ability, extra absorbability, or antibiotic properties. At the nanoscale, copper, normally opaque, becomes transparent; stable aluminum turns combustible; and gold, usually solid, becomes a liquid. Nano silver, an antibacterial, is used in bandages, socks and food packaging. Zinc oxide nanoparticles are found in sunscreen and cosmetics. Nano titanium dioxide is used in medicine capsules, nutritional supplements, food additives, skin creams, and toothpaste; and in foods like coconut and yogurt as a whitener.

Nanotechnology involves the creation of nanostructures like carbon-based graphene (a sheet of carbon atoms 1 atom thick) or carbon nanotubes (a tube of carbon atoms), which are excellent conductors of electricity; as well as the use of nanoparticles that are combined with other materials to optimize certain characteristics.

Scientists working in nanotechnology usually use molecules as building blocks. As an example, they may make something partly out of silicon, combined with an organic molecule and some nano widgets to produce a multifaceted nanostructure unlike anything found in nature, explained James Yardley, managing director of Columbia University's Nanoscale Science and Engineering Center. The choice of materials often depends on the area of research. Electronics researchers, for instance, often work with silicon or carbon; biotechnology researchers work with larger organic molecules; and materials researchers might utilize iron, steel or chromium.

Columbia's Nanoscale Science and Engineering Center, one of the first nanoscale science and engineering centers established by the National Nanotechnology Initiative, focuses its research on electronics. Scientists here, pioneers in research on graphene (the strongest material known to man per unit weight), are figuring out how to use it to replace silicon, essential in semiconductors and many electronic products. They are using it to develop applications for solar cells, touchscreens and sensors. The center is also working with carbon nanotubes, which are enabling the development of new electronic devices; and building photovoltaic devices on the nanoscale to make them much more efficient.

Every day, scientists are coming up with new applications for nanotechnology. An international nano research center has created a nanofiber mesh that can remove toxins from the blood, which could eliminate the need for dialysis for kidney failure patients. Swiss researchers recently succeeded in producing uniform antimony nanocrystals, which can store a large number of lithium and sodium ions, and could one day be used to produce high-energy-density batteries.

In the future, nanotechnology is expected to make communication and information technologies faster and cheaper, and create super-hard materials. In medicine, nanomaterials will be used as tiny sensors to detect disease or as chips to monitor bodily processes, for implants, and as drug delivery systems that can target specific cells. Nanomaterials will be able to filter pollutants from the environment or remove them from waste effluents. Nanotechnology will benefit space exploration by making lighter-weight vehicles and smaller robotic systems possible. Nano detectors of chemical and biological agents will improve national security. Some scientists predict that one day, they will be able to create programmable nanomatter whose properties can be controlled or altered.

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The promise and peril of nanotechnology