ACS Chemistry for Life

Advance toward producing biofuels without stressing global food supply
Journal of the American Chemical Society

Christopher Voigt and colleagues are reporting use of a first-of-its-kind approach to craft genetically engineered microbes with the much-sought ability to transform switchgrass, corn cobs, and other organic materials into methyl halides – the raw material for making gasoline and a host of other commercially important products. The new bioprocess could help pave the way for producing biofuels from agricultural waste, easing concerns about stress on the global food supply from using corn and other food crops. Plants and microbes produce methyl halides naturally, but in amounts too small for commercial use. Using a database of 89 genes from plants, fungi, and bacteria known to produce methyl halides, the researchers identified genes that were the most likely to produce the highest levels of these substances. The scientists then spliced these genes into Brewer’s yeast – used to make beer and wine – so that the yeast cells churned out methyl halides instead of alcohol. In laboratory studies, the two engineered microbes helped boost methyl halide production from switchgrass, corn cob husks, sugar cane waste, and poplar wood to levels with commercial potential.

Solar energy technology gets more visually-appealing makeover
Chemical & Engineering News

C&EN Senior Business editor Melody Voith notes that scientists, engineers, and architects are developing new solar panels, including materials that resemble normal shingles and invisible solar films that can cover glass windows. There’s a rapidly growing demand for these so-called building-integrated photovoltaics, or BIPV, that blend solar technology into the overall building aesthetic. One estimate suggests that the market for BIPV will grow by 18 percent a year through 2014, with revenues of about $780 million, according to the article. Several hurdles stand in the way of further expansion of this new solar technology, including a need for more efficient solar cells and demand for more durable and cost-effective materials. Although buildings clad in nearly invisible solar cells are mostly visions of the future, government incentives and ongoing technology improvements could combine to make this dream a widespread reality, the article suggests.

Plastics in oceans decompose, release hazardous chemicals, surprising new study says
239th National Meeting of the American Chemical Society

In the first study to look at what happens over the years to the billions of pounds of plastic waste floating in the world’s oceans, scientists are reporting that plastics – reputed to be virtually indestructible – decompose with surprising speed and release potentially toxic substances into the water. “Plastics in daily use are generally assumed to be quite stable,” said study lead researcher Katsuhiko Saido, Ph.D. “We found that plastic in the ocean actually decomposes as it is exposed to the rain and sun and other environmental conditions, giving rise to yet another source of global contamination that will continue into the future.” He said that polystyrene begins to decompose within one year, releasing components that are detectable in the parts-per-million range. Those chemicals also decompose in the open water and inside marine life. However, the volume of plastics in the ocean is increasing, so that decomposition products remain a potential problem.

Toward the design of greener consumer products
Journal of Physical Chemistry A

Scientists are reporting development of a new method for screening molecules and predicting how certain materials, ranging from chemicals used in carpeting to electronics, will contribute to global warming. In the study, Timothy Lee, Partha Bera, and Joseph Francisco note that carbon dioxide is the main greenhouse gas, which traps heat near Earth’s surface like the panes of glass in a greenhouse. However, other gases have the same effect, and in fact are even more efficient greenhouse gases than carbon dioxide. Scientists know that the molecules in gases differ in their ability to contribute to global warming, but they know little about the molecular basis. The scientists analyzed more than a dozen molecules involved in global warming to find out which chemical and physical properties are most important in determining their inherent radiative efficiency, and thus possess the largest potential to contribute to global warming. They found that molecules containing several fluorine atoms tend to be strong greenhouse gases, compared to molecules containing chlorine and/or hydrogen, and that molecules containing several fluorine atoms bonded to the same carbon increase their radiative efficiency in a non-linear fashion.

“Green” roofs may help put lid on global warming
Environmental Science & Technology

“Green” roofs, those increasingly popular urban rooftops covered with plants, could help fight global warming, scientists in Michigan are reporting. Kristin Getter and colleagues found that replacing traditional roofing materials in an urban area the size of Detroit, with a population of about one million, with green would be equivalent to eliminating a year’s worth of carbon dioxide emitted by 10,000 mid-sized SUVs and trucks. “Green” roofs reduce heating and air conditioning costs, retain and detain stormwater, and absorb carbon dioxide, a major greenhouse gas that contributes to global warming, but nobody had measured the impact until now. The scientists measured carbon levels in plant and soil samples collected from 13 green roofs in Michigan and Maryland over a two-year period. They found that green roofing an urban area of about one million people would capture more than 55,000 tons of carbon.

Probing the mysterious second-wave of damage in head injury patients
Chemical & Engineering News

Why do some of the one million people who sustain head injuries annually in United States experience a mysterious second wave of brain damage days after the initial injury – just when they appear to be recovering? C&EN Senior Editor Celia Henry Arnaud describes a phenomenon called depolarization, in which brain activity decreases in patients following initial trauma. The condition involves a wave of chemical changes that spread from the site of injury and inactivate nerve cells. Since reactivation of these cells requires large amounts of glucose, monitoring glucose levels in a patient’s brain can help doctors tell whether or not a patient is taking a turn for the worse. The article points out a promising new device, now in development at Imperial College London, that uses the new so-called “microfluidic method” to measure glucose quickly and continuously – in fractions of a second instead of hourly. The device is currently being tested in patients who have suffered trauma, stroke, or aneurysm (a balloon-like enlargement of a brain artery).

Built-in timer for improving accuracy of cost saving paper-strip medical tests
Analytical Chemistry

Scott Phillips and Hyeran Noh are reporting the development of a simple, built-in timer intended to improve the accuracy of paper tests and test strips for diagnosing diseases inexpensively at home and elsewhere. When fully developed, these low-cost paper tests may replace more expensive traditional tests for detecting biomarkers in urine, blood, and other body fluids, as well as for detecting pollution in water, but they require precise timing using a stopwatch to provide accurate results. For instance, the CHEMCARD diagnostic test for measuring blood sugar or cholesterol in a drop of blood, is almost 100 percent accurate when users view test results exactly 3 minutes after placing the drop of blood on the paper, but incorrect timing cuts accuracy nearly in half. Patients (particularly those in the developing world), they indicate, may not have stopwatches or other timing devices, or may not use external timing devices with enough accuracy to obtain meaningful results. The scientists describe the development of a built-in timer for paper-based diagnostic tests made from a dye and the paraffin wax used in some candles. Addition of water, blood, urine or other body fluids starts the timer, and a color change signals when the time is up. When used with a test similar to the CHEMCARD glucose test, the timer was 97 percent accurate, slightly better than when a stopwatch was used.

Scientific evidence supports effectiveness of Chinese drug for cataracts
Inorganic Chemistry

Tzu-Hua Wu, Fu-Yung Huang, Shih-Hsiung Wu and colleagues are reporting a scientific basis for the long-standing belief that a widely used non-prescription drug in China and certain other countries can prevent and treat cataracts, a clouding of the lens of the eye that is a leading cause of vision loss worldwide. Eye drops containing pirenoxine, or PRX, have been reputed as a cataract remedy for almost 60 years, but there have been few scientific studies on its actual effects. Currently, the only treatment for cataracts in Western medicine is surgical replacement of the lens, the clear disc-like structure inside the eye that focuses light onto the nerve tissue in the back of the eye. The scientists tested pirenoxine on cloudy solutions that mimic the chemical composition of the eye lens of cataract patients. The solutions contained crystallin – a common lens protein – combined with either calcium or selenite, two minerals whose increased levels appear to play key roles in the development of cataracts. Presence of PRX reduced the cloudiness of the lens solution containing calcium by 38 percent and reduced the cloudiness of the selenite solution by 11 percent.

Killer paper for next-generation food packaging
Langmuir

Aharon Gedanken and colleagues are reporting development and successful lab tests of “killer paper,” a material intended for use as a new food packaging material that helps preserve foods by fighting the bacteria that cause spoilage. The paper contains a coating of silver nanoparticles, which are powerful anti-bacterial agents. Nanoparticles, which have a longer-lasting effect than larger silver particles, could help overcome the growing problem of antibiotic resistance, in which bacteria develop the ability to shrug-off existing antibiotics. However, producing “killer paper” suitable for commercial use has proven difficult. The scientists describe development of an effective, long-lasting method for depositing silver nanoparticles on the surface of paper that involves ultrasound, or the use of high frequency sound waves. The coated paper showed potent antibacterial activity against E. coli and S. aureus, two causes of bacterial food poisoning, killing all of the bacteria in just three hours.

Forty-year-old test procedure finds modern niche in developing new medicines
Chemical & Engineering News

C&EN Senior Editor Celia Henry Arnaud notes that collecting drops of blood from patients and depositing the drops on special paper cards to dry has been used for decades to screen newborns for hereditary disorders and infectious disease. But the dried blood spot technology has found a new role at pharmaceutical companies in the development and testing of new drugs. The approach, possible now because modern lab instruments are more sensitive, has distinct advantages. The dried blood approach, for instance, involves taking only a few drops of blood from patients in clinical trials, and these can be stored and shipped more easily and inexpensively than liquid samples. Those advantages, alone, could cut the cost of introducing new drugs by millions of dollars, the article indicates.

Discovery of a biochemical basis for broccoli’s cancer-fighting ability
Journal of Medicinal Chemistry

Fung-Lung Chung and colleagues are reporting discovery of a potential biochemical basis for the apparent cancer-fighting ability of broccoli and its veggie cousins that targets and blocks a defective gene associated with cancer. They showed in previous experiments that substances called isothiocyanates (or ITCs) – found in broccoli, cauliflower, watercress, and other cruciferous vegetables – appear to stop the growth of cancer. But nobody knew exactly how these substances work, a key to developing improved strategies for fighting cancer in humans. The tumor suppressor gene p53 appears to play a key role in keeping cells healthy and preventing them from starting the abnormal growth that is a hallmark of cancer. When mutated, p53 does not offer that protection, and those mutations occur in half of all human cancers. The researchers found that ITCs are capable of removing the defective p53 protein but apparently leave the normal one alone. Drugs based on natural or custom-engineered ITCs could improve the effectiveness of current cancer treatments or lead to new strategies for treating and preventing cancer.

Trash to treasure: Turning steel-mill waste into bricks
Industrial & Engineering Chemistry Research

In the report, Ana Andrés and colleagues note that steel mills around the world produce vast quantities of waste dust each year – 8 million – 12 million tons in the United States, for instance, and 700,000 tons in the European Union countries. The dust often is converted into a rock-like material known as Waelz slag, which is usually disposed of in landfills and contains iron, calcium, silicon oxide and other minor oxides as manganese, lead or zinc oxide. Scientists have been searching for practical and safe uses for Waelz slag. In earlier research, scientists showed that Waelz slag had potential as an ingredient in bricks, roof tiles and other ceramic products. The new research moves large-scale recycling of Waelz slag closer to reality, establishing at two real-world brick factories that the material can successfully be incorporated into commercial-size bricks. The findings also eased concerns about large amounts of potentially toxic metals leaching out of such bricks.