Interesting tech developments in nanotech, nanostructured materials, etc.
Wednesday, January 14, 2004
Can Nanoparticles Enter Our Brains?
: "In a study carried out on rats, U.S. researchers have shown that carbon nanoparticles can move inside the brain after being inhaled
, and also move from the lungs into the bloodstream. Both Nature
and the Guardian
publish interesting stories about this potential new danger to our health. Let's start with Nature.
Günter Oberdörster of the University of Rochester in New York and colleagues tracked the progress of carbon particles that were only 35 nanometres in diameter and had been inhaled by rats. In the olfactory bulb -- an area of the brain that deals with smell -- nanoparticles were detected a day after inhalation, and levels continued to rise until the experiment ended after seven days.
.. Little is known about what effect nanoparticles will have when they reach the brain. The toxicity of the nanoparticles that are currently being used to build prototype nanosized electronic circuits -- such as carbon nanotubes, which are produced in labs around the world -- has not been thoroughly assessed.
But Donaldson says that there is a growing feeling that other nanoparticles, such as those produced by diesel exhausts, may be damaging to some parts of our body. He estimates that people in cities take in about 25 million nanoparticles with every breath. These particles are believed to increase respiratory and cardiac problems, probably by triggering an inflammatory reaction in the lungs.."
Chemists Grow Nano Menagerie
: "Researchers from Sandia National Laboratories have found a simple way to make tiny, complicated shapes from zinc oxide, including arrays of vertically-aligned rods, flat disks, and columns that resemble stacks of coins. The researchers grew the structures, which are similar to those found in biomaterials, by seeding a solution with zinc oxide nanoparticles. They were able to produce different shapes by changing the amount of citrate in the solution at different points during particle growth.
Zinc oxide is a widely-used, inexpensive ceramic material that has useful optical and semiconductor properties and can also be used as a catalyst. The material is already used in solar cells, microsensors and decontamination systems...
Zinc oxide nanostructures could be used as catalysts within the next two years, for chemical and biological sensing into five years, and for more efficient photovoltaics in something more than five years, according to the researchers. The work appeared in the November 23, 2003 issue of Nature Materials." Zinc oxide has been shown to catalyze the conversion of methane to carbon nanotubes and hydrogen. 10:19:34 PM
Nanotubes Detect Nerve Gas
: "Naval Research Laboratory researchers have found that carbon nanotubes are sensitive to extremely small concentrations—less than one part per billion—of chemical nerve agents. .. The researchers worked out a simple procedure to fabricate nanotube-based sensors from random networks of single-walled carbon nanotubes and used a prototype to detect dimethyl methylphosphonate, which simulates the nerve agent sarin. The networks of nanotubes form transistors; the presence of a nerve agent increases the nanotubes' resistance to electricity.
The sensors are very inexpensive, require very little power, and could be used to detect sub-parts-per-billion concentrations of nerve agents, other chemical warfare agents, and other toxic chemicals, according to the researchers. They made a prototype sensor contained in a quartz tube one-eighth of an inch wide by two inches long.
The researchers also showed that the nanotube network sensors can be combined with filters coated with polymers that are sensitive to certain chemicals to make sensors that detect specific chemicals. Arrays of the sensors could be incorporated into handheld or remotely-operated devices designed to detect a variety of substances, according to the researchers. Carbon nanotube sensors could become practical within two to five years, according to the researchers. " 10:16:58 PM
Body Handles Nanofiber Better
: "Researchers from Purdue University have made a discovery that may help: carbon nanofibers are surprisingly compatible with human tissue. The material could eventually be used to create better bone and neural implants. .. The researchers experiments showed that increasing the amount of carbon nanofibers in a polycarbonate urethane composite implant increased the functions of nerve and bone-forming cells and decreased the function of scar-tissue formation. The results imply that compatibility has to do with the size of the fibers that make up the materials.
The researchers have also shown that other materials that contain surfaces with nano-size features are also more compatible with the human body. Carbon nanofiber materials could be used in orthopedics in five to ten years, but it will be one to two decades before neural applications are practical, according to the researchers. " 10:14:21 PM