EVANSTON, Ill. --- When mercury is dumped into rivers and lakes, the toxic heavy metal can end up in the fish we eat and the water we drink. To help protect consumers from the diseases and conditions associated with mercury, researchers at Northwestern University in collaboration with colleagues at Ecole Polytechnique Fdrale de Lausanne (EPFL) in Switzerland, have developed a nanoparticle system that is sensitive enough to detect even the smallest levels of heavy metals in our water and fish.
The research was published September 9 in the journal Nature Materials.
"The system currently being used to test for mercury and its very toxic derivative, methyl mercury, is a time-intensive process that costs millions of dollars and can only detect quantities at already toxic levels," said Bartosz Grzybowski, lead author of the study. "Ours can detect very small amounts, over million times smaller than the state-of-the-art current methods. This is important because if you drink polluted water with low levels of mercury every day, it could add up and possibly lead to diseases later on. With this system consumers would one day have the ability to test their home tap water for toxic metals."
Grzybowski is the Kenneth Burgess Professor of Physical Chemistry and Chemical Systems Engineering in the Weinberg College of Arts and Sciences and the McCormick School of Engineering and Applied Science.
The new system is comprised of a commercial strip of glass covered with a film of "hairy" nanoparticles, a kind of a "nano-velcro," that can be dipped into water. When a metal cation --- a positively charged entity, such as a methyl mercury --- gets in between two hairs, the hairs close up, trapping the pollutant and rendering the film electrically conductive.
A voltage-measuring device reveals the result; the more ions there are trapped in the "nano-velcro," the more electricity it will conduct. To calculate the number of trapped p
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