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 During HIV infection, antibody can block B cells from fighting pathogens
14.08.2018 | NIH/National Institute of Allergy and Infectious Diseases

nachricht First study on physical properties of giant cancer cells may inform new treatments
14.08.2018 | Brown University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>