Chemistry News Archive May 2011

Chemistry:

Metal-free Click Polymerization of Propiolates and Azides

Polymer Films by Click Chemistry

Signpost for chemical snaps: copper ions as morphogens for the formation of polymer films by click chemistry.

Image: A polymer film is obtained by the Cu(I)-catalyzed Sharpless click reaction between two polymers, bearing either azide or alkyne groups, both present simultaneously in a Cu(II) solution (see picture). The Cu(I) morphogen is generated at an electrode by applying an adequate potential. This concept can be extended to supramolecular films formed by coordination complexes [Credit: Angewandte Chemie International Edition].

Direct Air Capture of Carbon Dioxide with Chemicals

Light-triggered Activation of Myosin

Nano-motor with a light switch: light-triggered myosin allows real-time study of cells.

[Credit: Angewandte Chemie International Edition]

Cassyrane: A Hint of Blackcurrant

Physics:

Infrared Nanospectroscopy With a Thermal Source

CIC nanoGUNE develops Nano-FTIR-nanoscale infrared spectroscopy with a thermal source.

Image: The tip is illuminated with the broadband infrared radiation from of a thermal source and the backscattered light is analyzed with a Fourier spectrometer, yielding local infrared spectra with a spatial resolution better than 100 nm. The displayed graph shows infrared spectra of differently processed oxides in an industrial semiconductor device [Copyright F. Huth, CIC nanoGUNE].

The First Sighting of Fluorine-14

A recent discovery of an extremely exotic, short-lived nucleus called fluorine-14 in laboratory experiments may indicate that scientists are gaining a better grasp of the rules of strong interaction.

Image: This graph shows the flourine-14 supercomputer predictions (far-left) and experimental results (center) [Credit: James Vary].

A Remarkable Advance in NMR Spectroscopy

Nuclear magnetic resonance with no magnets.

Image: Hydrogen molecules consist of two hydrogen atoms that share their electrons in a covalent bond. In an orthohydrogen molecule, both nuclei are spin up. In parahydrogen, one is spin up and the other spin down. The orthohydrogen molecule as a whole has spin one, but the parahydrogen molecule has spin zero [Credit: Lawrence Berkeley National Laboratory].

Chemistry and Nanotechnology:

Road for Producing Nanoribbons of Graphane

An international research team has discovered a new method to produce belts of graphene called nanoribbons. By using hydrogen, they have managed to unzip single-walled carbon nanotubes. The method also opens the road for producing nanoribbons of graphane, a modified and promising version of graphene.

Image: Reaction of single-walled carbon nanotubes (SWNTs) with hydrogen gas was studied in a temperature interval of 400–550 °C and at hydrogen pressure of 50 bar [Credit: The Swedish Research Council].

Sharpening the Nanofocus

Berkeley Lab researchers use nanoantenna to enhance plasmonic sensing.

Image: This is a scanning electron microscopy image showing a palladium nanoparticle with a gold antenna to enhance plasmonic sensing [Image courtesy of Alivisatos group].

Chemistry and Environment:

Silver Cycle

Chemistry and Research:

Photosynthesis or Photovoltaics?

Which is more efficient at harvesting the sun's energy, plants or solar cells? This salient question and an answer are the subject of an article published in the May 13, 2011 issue of the journal Science.

Image: Photosynthesis or photovoltaics: Weighing the impact [Credit: Bob Blankenship].

More News (open access):

Following your steak’s history from pasture to plate

The package on a supermarket steak may say “grass-fed” or “grass-finished,” but how can a consumer know whether the cow spent its days grazing peacefully on meadow grass or actually gorged on feedlot corn? In ACS’s Journal of Agricultural and Food Chemistry, scientists are now reporting the development of a method that can reconstruct the dietary history of cattle and authenticate the origins of beef.

Frank J. Monahan and colleagues note that consumers are increasingly concerned about the origins and labeling of meat, as they seek assurance about the meat’s safety or prepare to pay premium prices for specialty meats that are raised locally or certified as organic. “An example of such a product is pasture-fed beef,” they write, “often marketed as superior nutritionally as a result of increased levels of omega-3 fatty acids...arising from the consumption of grass.”

To reconstruct the diet of cattle, the researchers analyzed the proportions of different types of oxygen, nitrogen, hydrogen, and sulfur in the animals’ muscle tissue and tail hair. Specific diets (for instance, a diet that switched from mostly grass to corn at the end of the cow’s life) leave a distinctive “fingerprint” of these elements in cattle tissue. The fingerprint in muscle represents the animal’s overall lifetime diet, while quicker-growing tissue in tail hair can reveal more recent dietary changes. Monahan and colleagues say the fingerprints “provide a powerful tool to reconstruct changes in feed components offered to animals over periods of over a year and thus a tool to verify farm production practices.”

The authors acknowledge funding from the Irish Department of Agriculture, Fisheries and Food.

Journal of Agricultural and Food Chemistry: "Beef Authentication and Retrospective Dietary Verification Using Stable Isotope Ratio Analysis of Bovine Muscle and Tail Hair" [J. Agric. Food Chem., 2011, 59 (7), pp 3295–3305; DOI: 10.1021/jf1040959].

“Liquid smoke” from rice shows potential health benefits

Liquid smoke flavoring made from hickory and other wood - a mainstay flavoring and anti-bacterial agent for the prepared food industry and home kitchens - may get a competitor that seems to be packed with antioxidant, antiallergenic and anti-inflammatory substances, according to a new study in ACS’ Journal of Agricultural and Food Chemistry. It is the first analysis of liquid smoke produced from rice hulls, the hard, inedible coverings of rice grains.

Mendel Friedman, Seok Hyun Nam and colleagues explain that wood from trees is typically used to produce liquid smoke, added to meat and other foods for a smoky taste. But other types of plants can also be burned to make the popular seasoning. Rice is a prime candidate, with 680 millions tons produced worldwide each year. Hulls account for 136 million tons of that amount and often go to waste. The researchers wondered rice hulls could be put to good use in a liquid form as a food flavoring, and did the first studies needed to determine if rice hull smoke is safe enough for food use.

The scientists found that liquid smoke from rice hulls may be healthful. Their tests on laboratory cell cultures found that liquid rice hull smoke worked as an antioxidant that could help fight off diseases. It also helped prevent inflammation, which is associated with many different health problems did not trigger an allergic response. “New food uses of a major agricultural byproduct may benefit the environment, farmers, and consumers,” the report stated. “However, it is necessary to demonstrate that rice hull smoke is safe. The present study was designed to contribute to this assessment.”

The authors acknowledge funding from the Rural Development Administration, Republic of Korea.

Journal of Agricultural and Food Chemistry: "Composition of Liquid Rice Hull Smoke and Anti-Inflammatory Effects in Mice" [J. Agric. Food Chem., 2011, 59 (9), pp 4570–4581; DOI: 10.1021/jf2003392].

Toward a vaccine for methamphetamine abuse

Scientists are reporting development of three promising formulations that could be used in a vaccine to treat methamphetamine addiction - one of the most serious drug abuse problems in the U.S. The report appears in the Journal of the American Chemical Society.

In the paper, Kim Janda and colleagues note that methamphetamine use and addiction cost the U.S. more than $23 billion annually due to medical and law enforcement expenses, as well as lost productivity. The drug, also called “meth” or “crystal meth,” can cause a variety of problems including cardiovascular damage and death. Meth is highly addictive, and users in conventional behavioral treatment programs often relapse. Previously tested meth vaccines either are not effective or are very expensive. To overcome these challenges, the researchers made and tested new vaccine formulations that could potentially be effective for long periods, which would drive down costs and help prevent relapse.

The group found that three of the new formulations that produced a good immune response in mice (stand-ins for humans in the lab) were particularly promising. “These findings represent a unique approach to the design of new vaccines against methamphetamine abuse,” say the researchers.

The authors acknowledge funding from the National Institute on Drug Abuse and The Skaggs Institute for Chemical Biology.

Journal of the American Chemical Society: "Impact of Distinct Chemical Structures for the Development of a Methamphetamine Vaccine" [J. Am. Chem. Soc., 2011, 133 (17), pp 6587–6595; DOI: 10.1021/ja108807j].

The “$1,000 genome” may cost $100,000 to understand

Advances in technology have almost lifted the curtain on the long-awaited era of the “$1,000 genome” - a time when all the genes that make up a person can be deciphered for about that amount - compared to nearly $1 million a few years ago. But an article in the current edition of Chemical & Engineering News (C&EN), ACS’ weekly newsmagazine, raises the disconcerting prospect that a price tag of $100,000, by one conservative estimate, is necessary to analyze that genetic data so it can be used in personalized medicine – custom designing treatments that fit the patient’s genetic endowment.

In the article, C&EN Senior Editor Rick Mullin explains that while the cost of sequencing genes has dropped dramatically, the cost of analyzing genomic data so that it can be put to practical use in medicine has hardly budged. Today, assessing the genetic predispositions to disease means costly data analysis by specialists from several research areas, including molecular and computational biology, genetics, pathology and clinical science.

Mullin, however, cites several trends in bioinformatics that are opening the door to collection and processing of genetic data more economically and efficiently. One trend is to incorporate genomic analysis in commercial drug discovery and development efforts from the beginning. Another way to ease the burden is to reduce the amount of data that is generated - one instrument company recently developed a brand-new sequencing technology that generates much smaller data files, for example. Pharma researchers also are collaborating and sharing data like never before, and some of them are making use of public cloud computing and free, open-source software.

Chemical & Engineering News: "The Next Generation in Genome Sequencing" [May 9, 2011].

New evidence that caffeine is a healthful antioxidant in coffee

Scientists are reporting an in-depth analysis of how the caffeine in coffee, tea, and other foods seems to protect against conditions such as Alzheimer’s disease and heart disease on the most fundamental levels. The report, which describes the chemistry behind caffeine’s antioxidant effects, appears in ACS’ The Journal of Physical Chemistry B.

Annia Galano and Jorge Rafael León-Carmona describe evidence suggesting that coffee is one of the richest sources of healthful antioxidants in the average person’s diet. Some of the newest research points to caffeine (also present in tea, cocoa, and other foods) as the source of powerful antioxidant effects that may help protect people from Alzheimer’s and other diseases. However, scientists know little about exactly how caffeine works in scavenging the so-called free radicals that have damaging effects in the body. And those few studies sometimes have reached contradictory conclusions.

In an effort to bolster scientific knowledge about caffeine, they present detailed theoretical calculations on caffeine’s interactions with free radicals. Their theoretical conclusions show “excellent” consistency with the results that other scientists have report from animal and other experiments, bolstering the likelihood that caffeine is, indeed, a source of healthful antioxidant activity in coffee.

The Journal of Physical Chemistry B:

"Is Caffeine a Good Scavenger of Oxygenated Free Radicals?" [J. Phys. Chem. B, 2011, 115 (15), pp 4538–4546; DOI: 10.1021/jp201383y].

Natural protection against radiation

In the midst of ongoing concerns about radiation exposure from the Fukushima nuclear power plant in Japan, scientists are reporting that a substance similar to resveratrol — an antioxidant found in red wine, grapes and nuts — could protect against radiation sickness. The report appears in ACS Medicinal Chemistry Letters.

Michael Epperly, Kazunori Koide and colleagues explain that radiation exposure, either from accidents (like recent events in Japan) or from radiation therapy for cancer, can make people sick. High doses can even cause death. The U.S. Food and Drug Administration is currently evaluating a drug for its ability to protect against radiation sickness, but it is difficult to make in large amounts, and the drug has side-effects that prevent its use for cancer patients. To overcome these disadvantages, the researchers studied whether resveratrol — a natural and healthful antioxidant found in many foods — could protect against radiation injuries.

They found that resveratrol protected cells in flasks but did not protect mice (stand-ins for humans in the laboratory) from radiation damage. However, the similar natural product called acetyl resveratrol did protect the irradiated mice. It also can be produced easily in large quantities and given orally. The authors caution that it has not yet been determined whether acetyl resveratrol is effective when orally administered.

ACS Medicinal Chemistry Letters: "The Use of 3,5,4′-Tri-O-acetylresveratrol as a Potential Prodrug for Resveratrol Protects Mice from γ-Irradiation-Induced Death" [ACS Med. Chem. Lett., 2011, 2 (4), pp 270–274; DOI: 10.1021/ml100159p].

Cola detectives test natural flavoring claims for pricey soft drinks

Scientists are reporting development and successful testing of a new way to determine whether cola drinks — advertised as being made with natural ingredients and sold at premium prices — really do contain natural flavoring. The report appears in ACS’ Journal of Proteome Research.

In the study, Pier Giorgio Righetti and colleagues explain that cola drinks purportedly made from natural cola nuts are becoming popular and are sold in many natural food stores. Genuine cola “nuts” are seeds from the fruit of the cola tree, which is native to African rainforests, and they are expensive to harvest and ship. In West African cultures, people include the nuts in ceremonies and offer them to guests. The nuts also have possible health benefits — they may help treat whooping cough, asthma, migraines and dysentery. Most soft drink manufacturers don’t use cola nuts today, but a select few are starting to advertise cola as a natural ingredient in their products — and charge extra for it. To see whether consumers are getting what they pay for, the scientists set out to find a way to finger the drinks with real natural extracts.

The group found that testing for proteins was an accurate way to verify natural flavoring claims. They detected plant proteins in a drink claiming to have “organic agave syrup and cola nut extracts”. On the other hand, Coca Cola products — which do not claim to include cola extract — have no protein. The scientists say, “The identifications here obtained represent the quality mark of this beverage and, in a way, give a certificate of authenticity.”

Journal of Proteome Research: "Going nuts for nuts? The trace proteome of a Cola drink, as detected via combinatorial peptide ligand libraries" [J. Proteome Res., Article ASAP, 2011; DOI: 10.1021/pr2001447].

New woes for silicones in cosmetics and personal care products

At a time when cosmetics, shampoos, skin creams, and other personal care products already are going green / with manufacturers switching to plant-derived extracts and other natural ingredients  government regulators in Canada are adding to the woes of the silicone-based ingredients long used in these products. That’s the topic of an article in the current edition of Chemical & Engineering News (C&EN), ACS’ weekly newsmagazine.

C&EN Senior Correspondent Marc S. Reisch points out that manufacturers have used silicones for decades in an array of personal care products. Antiperspirants and underarm deodorants account for about half the entire U.S. personal care market for silicones. Manufacturers voluntarily stopped using one type of silicone ingredient in personal care products over the last decade. Now government regulators in Canada are proposing regulations limiting use of another widely used type of silicone ingredient. They cite concerns that the ingredients might built up in the environment and harm wildlife.

The article notes that some manufacturers, despite the concerns, are sticking with the traditional ingredients, termed cyclic methylsiloxanes. Others are using the concerns as a basis for jumping on the natural ingredient bandwagon and reformulating their products with other silicones or as “silicone-free.”

Chemical & Engineering News: "Storm Over Silicone" [Volume 89, Number 18, pp 10-13, DOI 10.1021/CEN042611142704].

New high-performance lithium-ion battery top candidate for electric cars

Scientists are reporting development of an advanced lithium-ion battery that is ideal for powering the electric vehicles now making their way into dealer showrooms. The new battery can store large amounts of energy in a small space and has a high rate capacity, meaning it can provide current even in extreme temperatures. A report on this innovation appears in ACS’ Journal of the American Chemical Society.

Bruno Scrosati, Yang-Kook Sun, and colleagues point out that consumers have a great desire for electric vehicles, given the shortage and expense of petroleum. But a typical hybrid car can only go short distances on electricity alone, and they hold less charge in very hot or very cold temperatures. With the government push to have one million electric cars on U.S. roads by 2015, the pressure to solve these problems is high. To make electric vehicles a more realistic alternative to gas-powered automobiles, the researchers realized that an improved battery was needed.

The scientists developed a high-capacity, nanostructured, tin-carbon anode, or positive electrode, and a high-voltage, lithium-ion cathode, the negative electrode. When the two parts are put together, the result is a high-performance battery with a high energy density and rate capacity. “On the basis of the performance demonstrated here, this battery is a top candidate for powering sustainable vehicles,” the researchers say.

The authors acknowledge funding from WCU (World Class University) program through the Korea Science and Engineering Foundation.

Journal of the American Chemical Society: "An Advanced Lithium Ion Battery Based on High Performance Electrode Materials" [J. Am. Chem. Soc., 2011, 133 (9), pp 3139–3143; DOI: 10.1021/ja110522x].

Notes: