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Wednesday, February 05, 2014

This is so cool!

A group of researchers has found a way to utilize mainstream technology to analyze a public health concern.  They are using a Smartphone camera with a special attachment and some pretty neat chemistry concepts to detect Hg2+ in water samples.  It is portable and relatively inexpensive compared to spectroscopic methods from what the article says.  I don’t know much about nanoparticles or metals chemistry but it seems possible to find some sort of similar technique to detect arsenic.  This sounds like it would be a helpful tool for the CWB arsenic projects. 

Latest News
Web Date: January 29, 2014

Smartphone Attachment Detects Ionic Mercury

Water Analysis: With the snap of a picture, a new device could screen for the toxic metal
Photograph of a smartphone sporting a new attachment for water testing.

Even Smarter Phone
A new smartphone attachment allows researchers to measure mercury ion concentrations in water samples by snapping a picture.
Credit: ACS Nano
new attachment for smartphones allows scientists to measure levels of ionic mercury, Hg2+, in water just by snapping a couple of pictures. The device could provide a quick, portable screening tool for the toxic metal (ACS Nano 2014, DOI: 10.1021/nn406571t).
Scientists worry about Hg2+ levels because the ions can damage people’s kidneys, and, in the environment, microbes can convert them into methylmercury, a neurotoxic compound that accumulates in fish that people eat. Currently, researchers detect ionic mercury in water with spectroscopic methods, which use equipment that is expensive and isn’t portable. Aydogan Ozcan of the University of California, Los Angeles, and his colleagues thought a smartphone-based device would solve both problems.
Their detection method involves adding a water sample to a salt solution containing gold nanoparticles and single-stranded nucleotides called aptamers. The aptamers envelop individual gold nanoparticles, keeping them separated from each other. But if the water sample contains Hg2+, the mercury ions bind to the aptamers, stripping them from the nanoparticles. The gold particles then start to clump, causing the light they emit to shift from red to blue. As the mercury ion concentration increases, so does the shift in the solution’s color.
The researchers use this shift to measure the Hg2+ concentration. They insert two tubes of the nanoparticle-aptamer solution into the smartphone attachment: one with the mercury-tainted water sample and one without. The apparatus shines red and green light onto the tubes and directs the light transmitted by the nanoparticle solutions toward the phone’s camera. A smartphone application determines the Hg2+ concentration based on color differences between pictures of the two tubes.
The technique can detect Hg2+ levels as low as 3.5 ppb, which is less sensitive than traditional methods but is close to theEnvironmental Protection Agency’s drinking water limit of 2 ppb. Ozcan says they possibly could improve the detection limit by shining more colors of light on the nanoparticle solutions.
Schematic for mercury sensing method using gold nanoparticles.

Mercury Spotting
To detect ionic mercury in water, researchers add the water samples to a solution of gold nanoparticles (red, left) coated with DNA aptamers (blue lines). The mercury ions (orange circles) bind to these aptamers, pulling them away from the nanoparticles (right). The gold nanoparticles then clump up and change their color from red to blue. A new attachment for smartphone cameras allows researchers to analyze this color change to determine the water sample’s mercury content.

1 comment:

  1. Very interesting, Jenny. Thanks for contributing this. We'll definitely look into it. Peace, Bego