Carbon Nanotubes May Help Bone Growth

Eric Berger, who writes the SciGuy blog for the Houston Chronicle writes about a study conducted at Rice University that used carbon nanotubes to help support bone growth in rabbit test subjects.

Two groups of rabbits were studied. One group received scaffolds made of 100% polypropylene fumarate, or PPF, which had performed well for bone growth scaffolding in previous studies. The second group received scaffolds made of 99.5% PPF and 0.5% single-walled carbon nanotubes.

The group that received that scaffolds that included the nanotubes showed substantially better bone growth at 12 weeks than the rabbits that received PPF-only scaffolds. Also, the composite scaffolds contained about two-thirds as much bone as the native bone tissues nearby, whereas the PPF contained only about one-fifth as much.

Researchers aren't sure why the carbon nanotubes had such a strong impact yet, and no research has been done in humans. But once this research advances further, we may find new ways to help heal bone fractures faster and more effectively.

Nanotubes May Be Hazardous to Your Health

Both the New York Times and the Los Angeles Times are running articles today highlighting a study reported in Nature Nanotechnology about the possible dangers of carbon nanotubes. These nano-scale structures, discovered in 1991, have potential for a massive number of industrial and commercial uses in the decades to come, but apparently come with some risks.

The researchers conducted a pilot study by injecting both long (20 micron) and short (5 micron) nanotubes into the abdominal cavities of mice. While the short nanotubes had little or no effect, the longer nanotubes caused lesions similar to those caused by asbestos, which the researchers believe would likewise cause mesothelioma, a form of cancer commonly caused by asbestos.

The results are preliminary, and the investigators point out that they did not study how easily nanotubes can become airborne or whether they become lodged in the lungs if inhaled. More research is needed into the harmfulness of nanotubes.

Researchers Develop Method to Control Water Flow Through Carbon Nanotubes

Researchers at Rensselaer Polytechnic Institute have developed a new method of controlling the flow of water through carbon nanotube membranes with an unprecedented level of precision. That may not sound that interesting, but it could lead to technologies designed to transform salt water into pure drinking water almost instantly, or to immediately separate a specific strand of DNA from the biological jumble.

Nanotube membranes have fascinated researchers with their combination of high flow rates and high selectivity, allowing them to filter out very small impurities and other organic materials like DNA and proteins from materials with high water content. The problem is that nanotube arrays are hydrophobic, strongly repelling water.

The researchers found a way to use low-voltage electricity to manipulate the flow of water through nanotubes. They discovered that when the nanotube’s membrane is given a small positive potential of only 1.7 volts, and the water is given a negative potential, the nanotubes quickly switch from repelling water to pumping water through the tube. When the charge on the water is raised, the water flows through at an exponentially faster rate. When the experiment is reversed with a negatively charged nanotube, it takes much higher voltage (90 volts) to move the water through the tube.