Chemistry News Archive December 2009

An inexpensive 'dipstick' test for pesticides in foods

Scientists in Canada are reporting the development of a fast, inexpensive "dipstick" test to identify small amounts of pesticides that may exist in foods and beverages. Their paper-strip test is more practical than conventional pesticide tests, producing results in minutes rather than hours by means of an easy-to-read color-change, they say.

The study was published in ACS' Analytical Chemistry, a semi-monthly journal. John Brennan and colleagues note in the new study that conventional tests for detecting pesticides tend to use expensive and complex equipment and in some cases can take several hours to produce results. They cite a growing need for cheaper, more convenient, and more eco-friendly tests for pesticides, particularly in the food industry.

The scientists describe the development of a new paper-based test strip that changes color shades depending on the amount of pesticide present. In laboratory studies using food and beverage samples intentionally contaminated with common pesticides, the test strips accurately identified minute amounts of pesticides. The test strips, which produced results in less than 5 minutes, could be particularly useful in developing countries or remote areas that may lack access to expensive testing equipment and electricity, they note.

Analytical Chemistry: "Reagentless Bidirectional Lateral Flow Bioactive Paper Sensors for Detection of Pesticides in Beverage and Food Samples" [Anal. Chem., 2009, 81 (21), pp 9055?9064; DOI: 10.1021/ac901714h].

Spider web glue spins society toward new biobased adhesives

With would-be goblins and ghosts set to drape those huge fake spider webs over doorways and trees for Halloween, scientists in Wyoming are reporting on a long-standing mystery about real spider webs: It is the secret of spider web glue. The findings are an advance toward a new generation of biobased adhesives and glues - "green" glues that replace existing petroleum-based products for a range of uses. A report on the study was published in ACS' Biomacromolecules, a monthly journal.

Omer Choresh and colleagues note that much research has been done on spider web silk, which rivals steel in its strength. However, scientists know comparatively little about web glue, which coats the silk threads and is among the world's strongest biological glues. Past studies revealed that spiders make web glue from glycoproteins, or proteins bits of sugar attached.

The scientists analyzed web glue from the golden orb weaving spider, noted for spinning intricate webs. They identified two new glycoproteins in the glue and showed that domains of these proteins were produced from opposite strands of the same DNA. "Once the cloned genes are over expressed in systems such as insect or bacterial cell cultures, large-scale production of the glycoprotein can be used to develop a new biobased glue for a variety of purposes," the report notes.

[Biomacromolecules: "Spider Web Glue: Two Proteins Expressed from Opposite Strands of the Same DNA Sequence" [Biomacromolecules, 2009, 10 (10), pp 2852?2856; DOI: 10.1021/bm900681w].

Chemistry makes the natural 'wonder fabric' - wool - more wonderful

Scientists in China are reporting an advance that may improve the natural wonders of wool - already regarded as the "wonder fabric" for its lightness, softness, warmth even when wet, and other qualities. They say the discovery could give wool a "brain," placing it among other "smart" fabrics that shake off wrinkles, shrinkage and "breathe" to release perspiration. The study is in ACS' Langmuir, a bi-weekly journal.

Fangqiong Tang, Yi Li and colleagues note that wool is naturally water-repellant, or hydrophobic, a feature that acts as a barrier to enhanced features such as anti-wrinkle, anti-shrinkage finishing and dyeing. Wool's water-repellency also hinders its ability to absorb moisture and makes wool garments feel sweaty. Although scientists have developed treatments that make wool more hydrophilic, or water-absorbing, they may not last long, may damage the fabric, and are not environmentally-friendly.

The scientists describe development of new coating that appears to ease these problems. It is made from silica nanoparticles of 1/50,000th the width of a human hair. The particles absorb excess moisture, and make wool superhydrophilic. The new layer does not affect wool's color or texture and can withstand dry cleaning, the scientists note.

Langmuir: "Fabricating Superhydrophilic Wool Fabrics" [Langmuir, Article ASAP; DOI: 10.1021/la903562h].

School classroom air may be more polluted with ultrafine particles than outdoor air

The air in some school classrooms may contain higher levels of extremely small particles of pollutants - easily inhaled deep into the lungs - than polluted outdoor air, scientists in Australia and Germany are reporting in an article in ACS' semi-monthly journal Environmental Science & Technology.

Lidia Morawska and colleagues note increasing concern in recent years over the health effects of airborne ultrafine particles. Evidence suggests that they can be toxic when inhaled into the lungs. Much of the scientific research, however, has focused on outdoor sources of these invisible particles, particularly vehicle emissions. Little research has been done, however, on indoor sources, and even less on ultrafine particles in school classrooms.

In an effort to fill those gaps in knowledge, the scientists studied levels of ultrafine particles in 3 elementary school classrooms in Brisbane, Australia. They found that on numerous occasions ultrafine particle levels in the classrooms were significantly higher than outdoors. The highest levels occurred during art activities such as gluing, painting and drawing when indoor levels were several times higher than outdoor levels. There also were significant increases in ultrafine particle levels when detergents were used for cleaning.

Environmental Science & Technology: "Ultrafine Particles in Indoor Air of a School: Possible Role of Secondary Organic Aerosols" [Environ. Sci. Technol., 2009, 43 (24), pp 9103?9109; DOI: 10.1021/es902471a].

Heart drugs show promise for fighting colon cancer

Scientists in Sweden are reporting for the first time that a group of drugs used to treat heart failure shows promise for fighting colon cancer. The study is in ACS' Journal of Natural Products, a monthly publication. Colon cancer is the third most common cancer in the United States, with more than 150,000 cases diagnosed in the U.S. each year.

Jenny Felth, Joachim Gullbo, and colleagues note that cardiac glycosides are a family of naturally-derived drugs used to treat congestive heart failure and abnormal heart rhythms. Scientists have suspected for some time, based on previous research, that these heart drugs may have promise for fighting many different types of cancer. Despite this, knowledge on effects in colon cancer or combination effects with other anti-cancer drugs is lacking. But scientists know little about their potential anticancer effects and have not tested these substances against colon cancer.

As part of a larger study to screen and identify natural substances with activity against colon cancer, the scientists picked several cardiac glycosides for further study. They tested five of these heart drugs against laboratory cultures of human colon cancer cells and found that they were all effective, to varying degrees, at killing the cancer cells. The sensitivity, however, was rather low when compared to that of other cancer cell types reported previously. Several of the drugs also showed increased anticancer activity when combined with certain drugs used for standard chemotherapy. The findings suggest that these heart drugs may affect colon cancer outcome when used alone or in combination with conventional chemotherapy drugs, they say.

Journal of Natural Products: "Cytotoxic Effects of Cardiac Glycosides in Colon Cancer Cells, Alone and in Combination with Standard Chemotherapeutic Drugs" [J. Nat. Prod., 2009, 72 (11), pp 1969?1974; DOI: 10.1021/np900210m].

Food aromas could become new weapon in battle of the bulge

A real possibility does exist for developing a new generation of foods that make people feel full by releasing anti-hunger aromas during chewing, scientists in the Netherlands are reporting after a review of research on that topic. Such foods would fight the global epidemic of obesity with aromas that quench hunger and prevent people from overeating. Their article appears in ACS' Journal of Agricultural and Food Chemistry, a bi-weekly publication.

Rianne Ruijschop and colleagues note that scientists long have tried to develop tasty foods that trigger or boost the feeling of fullness. Until recently, that research focused on food's effects in stomach after people swallow it. Efforts now have expanded to include foods that release hunger-quenching aromas during chewing. Molecules that make up a food's aroma apparently do so by activating areas of the brain that signal fullness.

Their analysis found that aroma release during chewing does contribute to the feeling of fullness and possibly to consumers' decisions to stop eating. The report cites several possible applications, including developing foods that release more aroma during chewing or developing aromas that have a more powerful effect in triggering feelings of fullness.

Journal of Agricultural and Food Chemistry: "Retronasal Aroma Release and Satiation: A Review" [J. Agric. Food Chem., 2009, 57 (21), pp 9888?9894; DOI: 10.1021/jf901445z].

Toward home-brewed electricity with 'personalized solar energy'

New scientific discoveries are moving society toward the era of "personalized solar energy," in which the focus of electricity production shifts from huge central generating stations to individuals in their own homes and communities. That's the topic of a report by an international expert on solar energy published in the ACS' Inorganic Chemistry, a bi-weekly journal. It describes a long-awaited, inexpensive method for solar energy storage that could help power homes and plug-in cars in the future while helping keep the environment clean.

Daniel Nocera explains that the global energy need will double by mid-century and triple by 2100 due to rising standards of living world population growth. Personalized solar energy - the capture and storage of solar energy at the individual or home level - could meet that demand in a sustainable way, especially in poorer areas of the world.

The report describes development of a practical, inexpensive storage system for achieving personalized solar energy. At its heart is an innovative catalyst that splits water molecules into oxygen and hydrogen that become fuel for producing electricity in a fuel cell. The new oxygen-evolving catalyst works like photosynthesis, the method plants use to make energy, producing clean energy from sunlight and water. "Because energy use scales with wealth, point-of-use solar energy will put individuals, in the smallest village in the nonlegacy world and in the largest city of the legacy world, on a more level playing field," the report states.

ACS Inorganic Chemistry: "Chemistry of Personalized Solar Energy" [Inorg. Chem., 2009, 48 (21), pp 10001?10017; DOI: 10.1021/ic901328v].

Behavior modification could ease concerns about nanoparticles

In an advance that could help ease health and environmental concerns about the emerging nanotechnology industry, scientists are reporting development of technology for changing the behavior of nanoparticles in municipal sewage treatment plants - their main gateway into the environment. Their study was published in ACS' journal Environmental Science & Technology.

Helen Jarvie from the UK Centre for Ecology and Hydrology and colleagues note that experts predict large increases in the production of nanoparticles - particles less than 1/1000th the width of a human hair - in the next decade. Manufacturers already use 2 million tons of nanoparticles each year in foods, cosmetics, medicines, and other consumer products. Studies have hinted that some nanoparticles could have adverse environmental health effects. Water discharged from sewage treatment plants is the major gateway for spread of nanoparticles to the aquatic environment. Scientists thus are focusing on how nanoparticles behave in wastewater and how that gateway might be closed off.

The study simulated (primary) sewage treatment to show that coating silica nanoparticles (similar to those used in ointments, toothpaste and household cleaners) with a detergent-like material made the nanoparticles clump together into the solid residue termed sewage sludge. Sludge often is stored in landfills or recycled as agricultural fertilizer. Uncoated nanoparticles, in contrast, stayed in the water and therefore remained in the effluent stream.

As the nanoparticles are simply too small to be visualized optically, the team used neutron scattering (at the UK's ISIS Facility) to view the sewage at the nano scale. The neutrons easily penetrate the sewage 'soup' and scatter strongly from the nanoparticles, allowing their aggregation behavior to be followed with time. The study demonstrates the potential for coating or otherwise changing the surface chemistry of nanoparticles to re-route their journey through sewage treatment plants, the scientists say.

Environmental Science & Technology: "Fate of Silica Nanoparticles in Simulated Primary Wastewater Treatment" [Environ. Sci. Technol., 2009, 43 (22), pp 8622?8628; DOI: 10.1021/es901399q].

Toward reading your own personal 'Book of Life'

What secrets about your risk for diseases are written in your own personal "Book of Life" - the 30,000 or so genes that make you you? Advances in DNA-sequencing technology are bringing closer the day when it will be more economical for consumers to get an answer to that question, and others, by ordering up the deciphering of their entire genetic endowment - their "personal genome." That's the possibility that Chemical & Engineering News, ACS' weekly newsmagazine, raises in a compelling new cover story. With their Book of Life in hand, consumers and their physicians could map out strategies for the prevention, early diagnosis, and more effective treatment of diseases ranging from cancer to rare-genetic disorders.

C&EN Senior Editor Celia Henry Arnaud notes that the first human genome sequence cost more than $2 billion and took about a decade to complete. Technological advances now have cut the time to as little as one week, and some companies are charging individuals $48,000 for the service, a cost that experts expect to drop sharply in the coming years, the article notes.

But the technology also raises important ethical and legal issues, including the possibility of discrimination on the basis of genetic information in the areas of employment and insurance coverage. Many believe that personal genomes are inevitable. "In the future, sequencing will be so cheap and so easy to access that everybody could get sequenced if they want. It'll be iPod pricing," says the CEO of a company that specializes in direct-to-consumer genome sequencing.

Chemical & Engineering News: "Your own personal genome" [December 14, 2009 Volume 87, Number 50pp. 13 - 15].

How calorie-restricted diets fight obesity and extend life span

Scientists searching for the secrets of how calorie-restricted diets increase longevity are reporting discovery of proteins in the fat cells of human volunteers that change as pounds drop off. The proteins could become markers for monitoring or boosting the effectiveness of calorie-restricted diets - the only scientifically proven way of extending life span in animals. Their study appears online in ACS' Journal of Proteome Research.

Edwin Mariman and colleagues note that scientists have long known that sharply restricting intake of calories while maintaining good nutrition makes animals live longer and stay healthier. Recent studies suggest that people may gain similar benefits. But scientists know little about how these diets work in humans, particularly their effects on cells that store fat.

The new study focused on proteins in abdominal subcutaneous fat cells from a group of overweight people before and after they went on a five-week-long calorie-restricted diet. The volunteers each lost an average of 21 pounds. Scientists identified changes in the levels of 6 proteins as the volunteers shed pounds, including proteins that tell the body to store fat. These proteins could serve as important markers for improving or tracking the effectiveness of therapies involving calorie-restricted diets, they say.

Journal of Proteome Research: "The physiologic effects of caloric restriction are reflected in the in vivo adipocyte-enriched proteome of overweight/obese subjects" [J. Proteome Res., 2009, 8 (12), pp 5532?5540; DOI: 10.1021/pr900606m].

Toward a fast, accurate urine test for pneumonia

Scientists are reporting a discovery of the potential basis for a urine test to diagnose community-acquired pneumonia (CAP), a difficult-to-diagnose disease that is the sixth leading cause of death in the United States. The test could save lives by allowing doctors to begin the right treatment earlier than often occurs at present. The study appears online in ACS' Journal of Proteome Research.

In the new study, Carolyn Slupsky points out that a variety of bacteria, viruses, and other microbes can cause pneumonia. Streptococcus pneumoniae (S. pneumoniae) is among the germs that cause CAP. These microbes can be difficult to detect using conventional blood tests, resulting in too-often delaying the start of the right antibiotic to best treat the disease.

The scientists measured metabolites in the urine of patients with pneumonia caused by S. pneumoniae and compared these metabolite profiles to those of urine samples from patients with other types of lung diseases, as well as pneumonia caused by a variety of other microbes. They found that infection with S. pneumoniae produces a distinct pattern of metabolites in much the same way that that the distinct whorls and curves in fingerprints can identify individuals. Identification of this pattern paves the way for more rapid diagnosis so that patients can start treatment sooner with the right medication, they say.

Journal of Proteome Research: "Pneumococcal Pneumonia: Potential for Diagnosis through a Urinary Metabolic Profile" [J. Proteome Res., 2009, 8 (12), pp 5550?5558; DOI: 10.1021/pr9006427].

New clues emerge for understanding morphine addiction

Scientists are adding additional brush strokes to the revolutionary new image now emerging for star-shaped cells called astrocytes in the brain and spinal cord. Their report, which suggests a key role for astrocytes in morphine's ability to relieve pain and cause addiction, appears online in ACS' Journal of Proteome Research, a monthly publication.

In the study, Piotr Suder and colleagues point out that nearly everyone viewed astrocytes - the most abundant cells in the brain - as supporting actors in the drama of brain activity. Scientists thought astrocytes simply propped up neurons, nerve cells that transmit signals, and kept them in proper position. Studies during the last several years, however, suggest that these cells are just as their Greek name suggests - stars.

The scientists added morphine to a group of astrocytes in cell culture for several days. They found that the morphine-exposed cells showed increased levels of nine proteins that appear to play a role in maintaining the normal function of nerve cells. "These proteins, after additional detailed study of their function, may serve as a potential marker of drug addiction, or may be the targets for potential therapy," the article notes.

Journal of Proteome Research: "The Proteomic Analysis of Primary Cortical Astrocyte Cell Culture after Morphine Administration" [J. Proteome Res., 2009, 8 (10), pp 4633?4640; DOI: 10.1021/pr900443r].