Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gold nanoparticles help detect a toxic metal -- mercury

30.04.2007
With gold nanoparticles, DNA and some smart chemistry as their tools, scientists at Northwestern University have developed a simple "litmus test" for mercury that eventually could be used for on-the-spot environmental monitoring of bodies of water, such as rivers, streams, lakes and oceans, to evaluate their safety as food and drinking water sources.

An article detailing the colorimetric screening technology and its success detecting mercury will be published online April 27 by Angewandte Chemie, the prestigious European journal of applied chemistry.

Methyl mercury, a neurotoxin that is particularly dangerous to young children and pregnant women, is the form of mercury people ingest when they eat contaminated fish and shellfish. Mercury is released into the air through industrial pollution, falling into bodies of water and polluting the waters in which fish and shellfish live. Bacteria in the aquatic environment then convert water-soluble mercuric ion (Hg2+) into methyl mercury, which accumulates in varying amounts in fish and shellfish.

"It is critical to detect mercury quickly, accurately and at its source," said Chad A. Mirkin, George B. Rathmann Professor of Chemistry, professor of medicine and professor of materials science and engineering, who led the study. "Most existing detection methods require expensive complicated equipment forcing tests to take place in a lab. Our method is simpler, faster and more convenient than conventional methods, and results can be read with the naked eye at the point of use."

The researchers report that they were able to determine by simple visual inspection if solvated mercuric ion was present in each sample tested and, if so, in what amount. As an illustration of the method's selectivity, they also could differentiate mercury from other metals with similar binding mechanisms, such as cadmium and copper.

The method is also highly sensitive, capable of detecting mercuric ions at the 100 nanomolar level. "To the best of my knowledge, we have set a record for the most sensitive colorimetric sensor," said Mirkin. "A glucose meter, for example, operates at a high micromolar scale, with glucose being 100,000 times more concentrated than the mercury we are detecting."

The Northwestern method takes advantage of gold's intense color when the metal is measured on the scale of atoms. Mirkin and his team started with gold nanoparticles, each just 15 nanometers in diameter, held together by complementary strands of DNA. Because they are held together within a certain critical distance, the gold nanoparticles -- and the solution they are in -- are blue. When the solution is heated, the DNA breaks apart, and the gold nanoparticles, no longer in close proximity to each other, are now bright red.

Knowing that mercuric ion binds selectively to the bases of a thymidine-thymidine (T-T) mismatch, the researchers designed each strand of DNA, which is attached to a gold nanoparticle, to have a single thymidine-thymidine (T-T) mismatch. If mercury is present in the solution it binds tightly to the T-T mismatch site.

The key to the technology is that the blue to red color change occurs at 46 degrees Celsius if the solution has no mercury, and it occurs at a higher temperature if mercury is present.

"When mercury binds to the T-T mismatch site it is like adding some superglue -- the gold nanoparticles are now held together even more tightly," said Mirkin. "The mercury creates a stronger bond that requires a higher temperature to break apart the DNA strands."

The temperature it takes to break apart the strands, when the color changes from blue to red, also indicates how much mercury is present -- the higher the temperature, the more mercury or "super glue" that is present.

Their next step, said Mirkin, is to increase the sensitivity of the method as well as expand the scope of environmental targets. Using similar principles, the researchers have started developing a colorimetric screening method for cadmium and lead.

"This is a simple method that we can tailor easily for other metals," said Mirkin.

Charles Loebbaka | EurekAlert!
Further information:
http://www.northwestern.edu

Further reports about: DNA Mirkin T-T gold nanoparticle mercuric mismatch nanoparticle

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>