Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nano-velcro clasps heavy metal molecules in its grips

10.09.2012
Researchers develop nano-strips for inexpensive testing of mercury levels in our lakes and oceans with unprecedented sensitivity

Mercury, when dumped in lakes and rivers, accumulates in fish, and often ends up on our plates. A Swiss-American team of researchers led by Francesco Stellacci at the Ecole Polytechnique Fédérale de Lausanne (EPFL) and Bartosz Grzybowski at Northwestern University has devised a simple, inexpensive system based on nanoparticles, a kind of nano-velcro, to detect and trap this toxic pollutant as well as others.

The particles are covered with tiny hairs that can grab onto toxic heavy metals such as mercury and cadmium. This technology makes it possible to easily and inexpensively test for these substances in water and, more importantly, in the fish that we eat. Their new method can measure methyl mercury, the most common form of mercury pollution, at unprecedentedly small attomolar concentrations. The system is outlined in an article appearing September 9, 2012 in the journal Nature Materials.

Methyl mercury, toxic and difficult to monitor

Researchers are particularly interested in detecting mercury. Its most common form, methyl mercury, accumulates as one goes up the food chain, reaching its highest levels in large predatory fish such as tuna and swordfish. In the US, France and Canada, public health authorities advise pregnant women to limit fish consumption because mercury can compromise nervous system development in the developing fetus.

"The problem is that current monitoring techniques are too expensive and complex," explains Constellium Chair holder at EPFL and co-author Francesco Stellacci. "We periodically test levels of mercury in drinking water, and if those results are good, we make the assumption that levels are acceptable in between those testing periods." But industrial discharge fluctuates.

A simple, inexpensive new technology

The technology developed by the Swiss-American team is simple to use. A strip of glass covered with a film of "hairy" nanoparticles is dipped into the water. When an ion – a positively charged particle, such as a methyl mercury or cadmium ion – gets in between two hairs, the hairs close up, trapping the pollutant.

A voltage-measuring device reveals the result; the more ions there are trapped in the nano-velcro, the more electricity it will conduct. So to calculate the number of trapped particles, all one needs to do is measure the voltage across the nanostructure.

By varying the length of the nano-hairs, the scientists can target a particular kind of pollutant. "The procedure is empirical," explains Stellacci. Methyl mercury, fortunately, has properties that make it extremely easy to trap without accidentally trapping other substances at the same time; thus the results are very reliable.

The interesting aspect of this approach is that the 'reading' glass strip could costs less than 10 dollars, while the measurement device will cost only a few hundreds of dollars. The analysis can be done in the field, so the results are immediately available. "With a conventional method, you have to send samples to the laboratory, and the analysis equipment costs several million dollars," notes Stellacci.

Convincing tests in Lake Michigan and Florida

The researchers tested the system in Lake Michigan, near Chicago. Despite the high level of industry in the region, mercury levels were extremely low. "The goal was to compare our measurements to FDA measurements done using conventional methods," explains Stellacci. "Our results fell within an acceptable range."

A mosquito fish from the Everglades in Florida was also tested. This species is not very high on the food chain and thus does not accumulate high levels of mercury in its tissues. "We measured tissue that had been dissolved in acid. The goal was to see if we could detect even minuscule quantities." says Bartosz Grzybowski, Burgess Professor of Chemistry and Director of Non-Equilibrium Energy Research Center at Northwestern University. The United States Geological Survey reported near-identical results after analyzing the same sample.

From quantum to real applications

"I think it is quite incredible," Grzybowski adds, "how the complex principles of quantum tunneling underlying our device translate into such an accurate and practically useful device. It is also notable that our system - through some relatively simple chemical modifications - can be readily adapted to detect other toxic species" Researchers have already demonstrated the detection of cadmium with a very high femtomolar sensitivity.

"With this technology, it will be possible to conduct tests on a much larger scale in the field, or even in fish before they are put on the market," says lead author Eun Seon Cho. This is a necessary public health measure, given the toxic nature of methyl mercury and the extremely complex manner in which it spreads in the environment and accumulates in living tissues.

Ecole Polytechnique Fédérale de Lausanne (EPFL): nanoparticles development

Northwestern University: sensing device conception and implementation – development of quantum mechanical models University of Michigan: modeling the trapping of ions

Funding for this research came from ENI, via the ENI-MIT Alliance; the US Defense Threat Reduction Agency via a grant to MIT and U Michigan; the US Department of Energy via a Nonequilibrium Energy Research Center grant to Northwestern and U Michigan.

Francesco Stellacci | EurekAlert!
Further information:
http://www.epfl.ch

More articles from Materials Sciences:

nachricht Scientists create innovative new 'green' concrete using graphene
24.04.2018 | University of Exeter

nachricht Neutrons provide insights into increased performance for hybrid perovskite solar cells
24.04.2018 | DOE/Oak Ridge National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Quantum Technology for Advanced Imaging – QUILT

24.04.2018 | Information Technology

AWI researchers measure a record concentration of microplastic in arctic sea ice

24.04.2018 | Earth Sciences

Complete skin regeneration system of fish unraveled

24.04.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>