Nano ‘velcro’ strip effective detector of water-borne contaminants

By Helen Albert, Senior medwireNews Reporter

Researchers have developed a specialized glass strip covered in "hairy" nanoparticles that can detect pollution of water by toxic metals, such as mercury.

The team says that the new strips have the advantage of being able to detect very low levels of contaminants, as well as being inexpensive to manufacture and easy to use.

"The problem is that current monitoring techniques are too expensive and complex," said study author Francesco Stellacci (Ecole Polytechnique Fédérale de Lausanne, Switzerland) in a press statement.

"With a conventional method, you have to send samples to the laboratory, and the analysis equipment costs several million dollars."

The strips and attached nanoparticles can be adapted to detect different pollutants by varying the length of the nanohairs on the particles. When the specific pollutant molecules fall between the nanohairs the hairs close up and trap the molecules.

In particular, the technology can successfully detect methyl mercury, even down to a very low concentration of 600 methyl mercury ions per cubic centimeter of water.

Unlike currently used methods of detecting toxic metal contaminants, such as atomic absorption spectroscopy and inductively coupled plasma spectroscopy, which can be expensive and complex, Stellacci and colleagues estimate that each strip will cost about US$ 10.00 (€ 7.77) and the machine to read the strips US$ 100-300 (€ 77.7-233.2) to produce.

"By making detection of pollutants and toxins cheap and easy to do, more testing at the source will lead to safer foods on the dinner table and in kids' lunchboxes," commented co-author of the Nature Materials paper Sharon Glotzer (University of Michigan, Ann Arbor, USA).

The researchers tested the strips on water from Lake Michigan and a mosquito fish caught in the lake for levels of mercury poisoning. The tissue from the fish was dissolved in acid before testing.

As expected from previous testing carried out by the US Food and Drug Administration (FDA) using more conventional methods, the water and fish levels of mercury were found to be very low.

"The goal was to compare our measurements to FDA measurements done using conventional methods," explained Stellacci.

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