Nanotube-infused Paper Detects Algae Toxin in Water
Engineers at the University of Michigan have led the development of a new biosensor made with carbon nanotubes and paper.
The paper strips perform 28 times faster than the method most commonly used to detect microcystin-LR (MC-LR), a chemical compound produced by cyanobacteria, or blue-green algae. Cyanobacteria is commonly found on nutrient-rich waters.
The substance is believed to be a culprit of mass poisonings going back to early human history, said Nicholas Kotov, a professor in the departments of Chemical Engineering, Biomedical Engineering and Materials Science and Engineering who led the project.
Water treatment plants can't always remove MC-LR completely, nor can they test for it often enough, Kotov said. The biosensor he and his colleagues developed provides a quick, cheap, portable and sensitive test that could allow water treatment plants and individuals to verify the safety of water on a more regular basis.
"The safety of drinking water is a vital issue in many developing countries and in many parts of the United States," Kotov said. "We've developed a simple and inexpensive technology to detect multiple toxins."
The technology could easily be adapted to detect a variety harmful chemicals or toxins in water or food.
A paper about the technique is published online in Nano Letters.
The sensor works by measuring the electrical conductivity of the nanotubes in the paper. Before the nanotubes are impregnated in the paper, they are mixed with antibodies for MC-LR. When the paper strips come in contact with water contaminated with MC-LR, those antibodies squeeze in between the nanotubes to bond with the MC-LR. This spreading apart of the nanotubes changes their electrical conductivity.
An external monitor measures the electrical conductivity. The whole device is about the size of a home pregnancy test, Kotov said. Results appear in fewer than 12 minutes.
To adapt the biosensor for other toxins, Kotov said, scientists could simply replace the antibodies that bond to the toxin.
This research was done in collaboration with the laboratory of professor Chuanlai Xu at Wuxi University in China. It is funded by the National Science Foundation, the Air Force Office of Scientific Research, and the National Institutes of Health, as well as the National Science Foundation of China and the 11th Five Years Key Programs for Science and Technology Development of China.
The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.