Paper Strip Detects Toxin

Engineers at the University of Michigan have led the development of a new biosensor in the form of a strip of paper infused with carbon nanotubes.
27/01/2010 Ámbito: América (Noticia leida 415 veces)

Water Parthnership-The strip can quickly and inexpensively detect a toxin produced by algae in drinking water.

The technology, which could easily be adapted to detect a variety of harmful chemicals or toxins in water or food, is described by Wang et al. in the journal Nano Letters.

The paper strips produce results 28 times faster than the complex method commonly used today to detect microcystin-LR, a chemical compound produced by cyanobacteria or blue-green algae. Cyanobacteria are commonly found in nutrient-rich waters.

Microcystin-LR (MC-LR), even in very small quantities, is suspected of causing liver damage and possibly liver cancer. The substance and others like it are among the leading causes of biological water pollution.

It is believed to be the cause of historical mass poisonings, said Nicholas Kotov. Kotov, a professor in the departments of Chemical Engineering, Biomedical Engineering and Materials Science and Engineering, was project leader of the biosensor development.

Water treatment plants (even in developed countries) cannot always remove MC-LR completely or test for it often enough, according to Kotov.

The biosensor which 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 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, which is then measured by an external monitor. The whole device is about the size of a home pregnancy test, and results appear in fewer than 12 minutes.

To adapt the biosensor for other toxins, scientists could simply replace the antibodies that bond to the toxin.

This research was carried out in collaboration with the laboratory of professor Chuanlai Xu at Wuxi University in China. The University of Michigan is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.