Tag Archives: mercury

‘Hunting’ pharmaceuticals and removing them from water

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Pharmaceuticals are not the first pollutants people think of when discussing water pollution but, for those who don’t know, it’s a big issue and scientists at the University of Surrey (UK) have developed a technology they believe will help to relieve the contamination. From an April 10, 2017 University of Surrey press release (also on EurekAlert),

The research involves the detection and removal of pharmaceuticals in or from water, as contamination from pharmaceuticals can enter the aquatic environment as a result of their use for the treatment of humans and animals. This contamination can be excreted unchanged, as metabolites, as unused discharge or by drug manufacturers.

The research has found that a new type of ‘supermolecule’, calix[4], actively seeks certain pharmaceuticals and removes them from water.

Contamination of water is a serious concern for environmental scientists around the world, as substances include hormones from the contraceptive pill, and pesticides and herbicides from allotments. Contamination can also include toxic metals such as mercury, arsenic, or cadmium, which was previously used in paint, or substances that endanger vital species such as bees.

Professor Danil de Namor, University of Surrey Emeritus Professor and leader of the research, said: “Preliminary extraction data are encouraging as far as the use of this receptor for the selective removal of these drugs from water and the possibility of constructing a calix[4]-based sensing devices.

“From here, we can design receptors so that they can bind selectively with pollutants in the water so the pollutants can be effectively removed. This research will allow us to know exactly what is in the water, and from here it will be tested in industrial water supplies, so there will be cleaner water for everyone.

“The research also creates the possibility of using these materials for on-site monitoring of water, without having to transport samples to the laboratory.”

Dr Brendan Howlin, University of Surrey co-investigator, said: “This study allows us to visualise the specific receptor-drug interactions leading to the selective behaviour of the receptor. As well as the health benefits of this research, molecular simulation is a powerful technique that is applicable to a wide range of materials.

“We were very proud that the work was carried out with PhD students and a final year project student, and research activities are already taking place with the Department of Chemical and Processing Engineering (CPI) and the Advanced Technology Institute (ATI).

“We are also very pleased to see that as soon as the paper was published online by the European Journal of Pharmaceutical Sciences, we received invitations to give keynote lectures at two international conferences on pharmaceuticals in Europe later this year.”

That last paragraph is intriguing and it marks the first time I’ve seen that claim in a press release announcing the publication of a piece of research.

Here’s a link to and a citation for the paper,

A calix[4]arene derivative and its selective interaction with drugs (clofibric acid, diclofenac and aspirin) by Angela F Danil de Namor, Maan Al Nuaim, Jose A Villanueva Salas, Sophie Bryant, Brendan Howlin. European Journal of Pharmaceutical Sciences Volume 100, 30 March 2017, Pages 1–8 https://doi.org/10.1016/j.ejps.2016.12.027

This paper is behind a paywall.

Using a sponge to remove mercury from lake water

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I’ve heard of Lake Como in Italy but Como Lake in Minnesota is a new one for me. The Minnesota lake is featured in a March 22, 2017 news item about water and sponges on phys.org,

Mercury is very toxic and can cause long-term health damage, but removing it from water is challenging. To address this growing problem, University of Minnesota College of Food, Agricultural and Natural Sciences (CFANS) Professor Abdennour Abbas and his lab team created a sponge that can absorb mercury from a polluted water source within seconds. Thanks to the application of nanotechnology, the team developed a sponge with outstanding mercury adsorption properties where mercury contaminations can be removed from tap, lake and industrial wastewater to below detectable limits in less than 5 seconds (or around 5 minutes for industrial wastewater). The sponge converts the contamination into a non-toxic complex so it can be disposed of in a landfill after use. The sponge also kills bacterial and fungal microbes.

Think of it this way: If Como Lake in St. Paul was contaminated with mercury at the EPA limit, the sponge needed to remove all of the mercury would be the size of a basketball.

A March 16, 2017 University of Minnesota news release, which originated the news item, explains why this discovery is important for water supplies in the state of Minnesota,

This is an important advancement for the state of Minnesota, as more than two thirds of the waters on Minnesota’s 2004 Impaired Waters List are impaired because of mercury contamination that ranges from 0.27 to 12.43 ng/L (the EPA limit is 2 ng/L). Mercury contamination of lake waters results in mercury accumulation in fish, leading the Minnesota Department of Health to establish fish consumption guidelines. A number of fish species store-bought or caught in Minnesota lakes are not advised for consumption more than once a week or even once a month. In Minnesota’s North Shore, 10 percent of tested newborns had mercury concentrations above the EPA reference dose for methylmercury (the form of mercury found in fish). This means that some pregnant women in the Lake Superior region, and in Minnesota, have mercury exposures that need to be reduced.  In addition, a reduced deposition of mercury is projected to have economic benefits reflected by an annual state willingness-to-pay of $212 million in Minnesota alone.

According to the US-EPA, cutting mercury emissions to the latest established effluent limit standards would result in 130,000 fewer asthma attacks, 4,700 fewer heart attacks, and 11,000 fewer premature deaths each year. That adds up to at least $37 billion to $90 billion in annual monetized benefits annually.

In addition to improving air and water quality, aquatic life and public health, the new technology would have an impact on inspiring new regulations. Technology shapes regulations, which in turn determine the value of the market. The 2015 EPA Mercury and Air Toxics Standards regulation was estimated to cost the industry around of $9.6 billion annually in 2020. The new U of M technology has a potential of bringing this cost down and make it easy for the industry to meet regulatory requirements.

Research by Abbas and his team was funded by the MnDRIVE Global Food Venture, MnDRIVE Environment, and USDA-NIFA. They currently have three patents on this technology. To learn more, visit www.abbaslab.com.

Here’s a link to and a citation for the paper,

A Nanoselenium Sponge for Instantaneous Mercury Removal to Undetectable Levels by Snober Ahmed, John Brockgreitens, Ke Xu, and Abdennour Abbas. Advanced Functional Materials DOI: 10.1002/adfm.201606572 Version of Record online: 6 MAR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Test your tuna for mercury and other heavy metals with nano-velcro

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Scientists Francesco Stellacci at the École Polytechnique Fédérale de Lausanne (EPFL) and Bartosz Grzybowski at Northwestern University have devised an easy and economical way to test for mercury and other heavy metals in fish. From the Sept. 9, 2012 news release on EurekAlert,

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.

Here’s a description of how the technique works, from the Sept. 12, 2012 news release on the EPFL website,

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.

They have tested the system in the field,

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 [US Food and Drug Administration] 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.

…

“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.

Northwestern University provided an illustration of the nano-velcro trapping an ion of heavy metal,

Nano-velcro (Courtesy Northwestern University & EPFL; downloaded from http://actu.epfl.ch/news/nano-velcro-clasps-heavy-metal-molecules-in-its-gr/)

Nanoremediation techniques from Iran and from South Carolina

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Researchers in Iran have announced a method of removing mercury from water. From the Aug. 6, 2012 news item on Nanowerk,

A research team from Martyr Chamran University of Ahvaz [Iran] succeeded in the elimination of mercury from aqueous media by using 2-mercaptobenzothiazole and by coating it on the magnetic iron oxide nanoparticles. Removal of mercury from water at lower concentrations was carried out by using the same compound successfully.

… According to the results of the experiments, the nano adsorbent is able to rapidly adsorb mercury at low concentrations. It causes the amount of mercury remaining in the environment to be less than the amount announced by WHO.

You can find the study (Fast and efficient removal of mercury from water samples using magnetic iron oxide nanoparticles modified with 2-mercaptobenzothiazole) behind a paywall in the Journal of Hazardous Materials.

Moving onto the work at Clemson University in South Carolina (US), researchers there have developed a dendrimer-fullerenol which could be used for cleaning up the environment and/or drug delivery. From the Aug. 6, 2012 news item on Nanowerk (Note: This seems to have been written by the study’s lead author, Priyanka Bhattacharya),

Our recent paper, “Dendrimer-fullerenol soft-condensed nanoassembly” [behind a paywall] published in The Journal of Physical Chemistry C, showed how the soft nanomaterial dendrimer can be used to remediate the environment from potentially toxic nanomaterials. Here, we used fullerenol – a 60 carbon molecule in the shape of a buckyball and functionalized with hydroxyl groups – as a model system. Such an assembly also has implications for drug delivery.

Here’s an image the researchers included with their published study,

Here we show that poly(amidoamine) (PAMAM) dendrimers of both generations 1 (G1) and 4 (G4) can host 1 fullerenol per 2 dendrimer primary amines as evidenced by isothermal titration calorimetry, dynamic light scattering, and spectrofluorometry. (downloaded from http://pubs.acs.org/doi/abs/10.1021/jp3036692)

Here’s a little more about the dendrimers,

Dendrimers are highly branched, polymeric macromolecules with a high degree of surface functionalities. Their branching determines their generation number (G) – the higher the generation, the greater the degree of surface functionalities. We used both G1 and G4 poly(amidoamine) (PAMAM) dendrimers and found that both these dendrimers hosted one fullerenol per primary amine on the dendrimer surfaces. However, G4 PAMAM dendrimers hosted fullerenols 40 times better than G1, simply because of their higher degree of surface functionalities. Based on our findings, we recommended proper loading capacities of fullerenols for G1 and G4 dendrimers in drug delivery and environmental remediation.

You can also find this news item in an Aug. 6, 2012 postingfeaturing images of the lead author (Priyanka Bhattacharya is a Ph.D. student at Clemson University’s College of Engineering and Science) on the ScienceCodex website,

Our group, led by my advisor Dr. Pu-Chun Ke and funded by the National Science Foundation, has delved into a crucial topic of frontier research termed “nanoparticle-protein corona”. In short, nanoparticles do not interact directly with living systems but are often coated with biological fluids in the form of a protein corona. Another direction in our group, through collaboration between Dr. Ke and Dr. David Ladner in Clemson’s Department of Environmental Engineering and Earth Sciences and funded by the U.S. Environmental Protection Agency is to employ dendritic polymers for remediating oil spills.

(It’s unusual to see a news release written in the first person.)

I’m glad to see more research about exploiting nanotechnology for environmental cleanups.

Dental fillings that improve your teeth

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If you have lousy teeth, this is exciting news. From the May 2, 2012 news item on Nanowerk (I have removed a link),

Scientists using nanotechology at the University of Maryland School of Dentistry have created the first cavity-filling composite that kills harmful bacteria and regenerates tooth structure lost to bacterial decay. [emphasis mine]

Rather than just limiting decay with conventional fillings, the new composite is a revolutionary dental weapon to control harmful bacteria, which co-exist in the natural colony of microorganisms in the mouth, says professor Huakun (Hockin) Xu, PhD, MS. [emphasis mine]

While the possibilities are promising, I find the idea of a weapon in my mouth disconcerting. (They might want to check out their metaphors a little more closely.) Moving on, there’s a little more detail about this new composite  (from the news item),

Fillings made from the School of Dentistry’s new nanocomposite, with antibacterial primer and antibacterial adhesive, should last longer than the typical five to 10 years, though the scientists have not thoroughly tested longevity. Xu says a key component of the new nanocomposite and nano-structured adhesive is calcium phosphate nanoparticles that regenerate tooth minerals. The antibacterial component has a base of quaternary ammonium and silver nanoparticles along with a high pH. The alkaline pH limits acid production by tooth bacteria.

“The bottom line is we are continuing to improve these materials and making them stronger in their antibacterial and remineralizing capacities as well as increasing their longevity,” Xu says.

The new products have been laboratory tested using biofilms from saliva of volunteers. The Xu team is planning to next test its products in animal teeth and in human volunteers in collaboration with the Federal University of Ceara in Brazil.

The folks at the enewsparkforest blog are not quite so sanguine about this dental development as per their May 3, 2012 posting on the topic (I have removed llinks),

A study conducted in 2008 and confirmed by another study in 2009 shows that washing nano-silver textiles releases substantial amounts of the nanosilver into the laundry discharge water, which will ultimately reach natural waterways and potentially poison fish and other aquatic organisms. A study found nanosilver to cause malformations and to be lethal to small fish at various stages of development since they are able to cross the egg membranes and move into the fish embryos. A 2010 study by scientists at Oregon State University and in the European Union highlights the major regulatory and educational issues that they believe should be considered before nanoparticles are used in pesticides.

As Dexter Johnson in his May 3, 2012 posting on his Nanoclast blog (on the Institute for Electrical and Electronics Engineers website) notes,

The researchers are continuing with their animal and human testing with the nanocomposite. Given that some sectors of the public are concerned about the potential risks of silver nanoparticles, they should probably take a look at the issue as part of their research.

This is not unreasonable especially in light of the concern some folks have had over mercury in dental fillings. Sufficient concern by the way to occasion this cautionary note from Health Canada (from the Mercury and Human Health webpage on their website),

Minimizing Your Risk

Elemental mercury from dental fillings does not generally pose a health risk. There is, however, a fairly small number of people who are hypersensitive to mercury. While Health Canada does not recommend that you replace existing mercury dental fillings, it does suggest that when the fillings need to be repaired, you may want to consider using a product that does not contain mercury.

Pregnant women, people allergic to mercury and those with impaired kidney function should avoid mercury fillings. Whenever possible, amalgam fillings should not be removed when you are pregnant because the removal may expose you to mercury vapour. When appropriate, the primary teeth of children should be filled with non-mercury materials.

Side note: I find it interesting that while Health Canada has not banned the use of mercury in fillings, it does advise against adding more mercury-laced fillings to your mouth and/or using them in your children’s primary teeth, if possible.

Getting back to silver nanoparticles in our mouths, I reiterate Dexter’s suggestion.