Chemistry News Archive November 2007

Magnetic nanoparticles detect and remove harmful bacteria

Researchers in Ohio report the development of magnetic nanoparticles that show promise for quickly detecting and eliminating E. coli, anthrax, and other harmful bacteria. In laboratory studies, the nanoparticles helped detect a strain of E. coli within five minutes and removed 88 percent of the target bacteria, the scientists say. Their study is scheduled for the Nov. 7 issue of the Journal of the American Chemical Society, a weekly publication.

Xuefei Huang and colleagues point out that ongoing incidents of produce contamination and the threat of bioterrorist attacks have created an urgent need for quicker, more effective ways to detect bacterial decontamination. To meet that need, they developed a �magnetic glyco-nanoparticle (MGNP),� a unique compound that combines magnetic nanoparticles with sugars.

Sugars (or carbohydrates) on cell surfaces are used by many bacteria to attach to their host cells in order to facilitate infection. The scientists exposed a group of E. coli bacteria to the sugar-coated nano-magnets to mark the microbes so they could be easily identified and removed by a magnetic device. The researchers also used the particles to distinguish between three different E. coli strains.

The study represents �the first time that magnetic nanoparticles have been used to detect, quantify, and differentiate E. coli cells,� the researchers state.

Journal of the American Chemical Society: �Magnetic Glyco-nanoparticles: A Unique Tool for Rapid Pathogen Detection, Decontamination, and Strain Differentiation� [PDF]

Sweet magnolia: Tree bark extract fights bad breath and tooth decay

�Sweet magnolia� does more than describe the fragrant blossoms of a popular evergreen tree. It also applies to magnolia bark�s effects on human breath. Scientists in Illinois are reporting that breath mints made with magnolia bark extract kill most oral bacteria that cause bad breath and tooth decay within 30 minutes. The extract could be a boon for oral health when added to chewing gum and mints, they report in a study scheduled for the Nov. 14 issue of the ACS� Journal of Agricultural and Food Chemistry, a bi-weekly publication.

Consumers often turn to flavored chewing gum and mints to battle bad breath. However, those products only temporarily mask the odor of bad breath, which is caused by bacteria. Existing anti-bacterial products for bad breath are far from ideal, with some having side effects like tooth staining.

In the new study, Minmin Tian and Michael Greenberg tested the germ-killing power of magnolia bark extract using saliva samples taken from volunteers following a regular meal. Mints containing the extract killed more than 61 percent of the germs that cause bad breath within 30 minutes, compared with only a 3.6 percent germ-kill for the same flavorless mints without the extract, the researchers say.

The extract also showed strong antibacterial activity against a group of bacteria known to cause cavities. Mints and chewing gum containing the extract may also provide a �portable oral care supplement to dentifrice (toothpaste), where brushing is not possible,� the study states.

Journal of Agricultural and Food Chemistry: �Compressed Mints and Chewing Gum Containing Magnolia Bark Extract Are Effective against Bacteria Responsible for Oral Malodor� [PDF]

Oceans could slurp up carbon dioxide to fight global warming

Researchers in Massachusetts and Pennsylvania are proposing a new method for reducing global warming that involves building a series of water treatment plants that enhance the ability of the ocean to absorb carbon dioxide from the atmosphere. About 100 such plants - which essentially use the ocean as �a giant carbon dioxide collector� - could cause a 15 percent reduction in emissions over many years, they say. About 700 plants could offset all Co2 emissions. Their study is scheduled to appear in the Dec. 15 issue of ACS� Environmental Science & Technology, a semi-monthly journal.

Scientists believe that excessive build-up of carbon dioxide in the air contributes to global warming. In addition to cutting down on carbon dioxide emissions by reducing the use of fossil fuels, researchers have focused on new technologies that remove the gas directly from the atmosphere.

In the new study, Kurt Zenz House and colleagues propose building hundreds of special water treatment facilities worldwide that would remove hydrochloric acid from the ocean by electrolysis and neutralize the acid through reactions with silicate minerals or rocks. The reaction increases the alkalinity of the ocean and its ability to absorb carbon dioxide from the atmosphere. The process is similar to the natural weathering reactions that occur among silicate rocks but works at a much faster rate, the researchers say.

Environmental Science & Technology: �Electrochemical Acceleration of Chemical Weathering as an Energetically Feasible Approach to Mitigating Anthropogenic Climate Change� [PDF]

New database screening criteria improves identification of anticancer drugs

Scientists in Indiana and Michigan have developed a better way of mining a vast computerized database for chemical nuggets that could become tomorrow�s cancer medications. The new �data mining� method pinpoints chemical structures with drug-like activity. It could speed the identification and development of new, more effective drugs against breast, prostate, lung and other cancers, according to a report scheduled for the Nov./Dec. issue of ACS� Journal of Chemical Information and Modeling, a bi-monthly publication.

Computers have become a mainstay in the drug discovery process and have led to the identification of dozens of promising anticancer drugs. However, as the amount and complexity of information in a chemical

In the new report, David J. Wild and colleagues analyzed data from the National Cancer Institute Developmental Therapeutics Program, a database of 40,000 compounds that have been tested against 60 tumor cell lines. The researchers identified a set of common structural features that can be used to more accurately predict which compounds are most active against cancer cells. In a series of experiments, they showed that applying these new criteria significantly increased the accuracy rate of identifying drug-like molecules in comparison to standard screening methods.

Journal of Chemical Information and Modeling: �Chemical Data Mining of the NCI Human Tumor Cell Line Database� [PDF]

�Wiring up� enzymes for producing hydrogen in fuel cells

Researchers in Colorado are reporting the first successful �wiring up� of hydrogenase enzymes. Those much-heralded proteins are envisioned as stars in a future hydrogen economy where they may serve as catalysts for hydrogen production and oxidation in fuel cells. Their report, describing a successful electrical connection between a carbon nanotube and hydrogenase, is scheduled for the Nov. issue of ACS' Nano Letters, a monthly journal.

In the new study, Michael J. Heben, Paul W. King, and colleagues explain that bacterial enzymes called hydrogenases show promise as powerful catalysts for using hydrogen in fuel cells, which can produce electricity with virtually no pollution for motor vehicles, portable electronics, and other devices. However, scientists report difficulty incorporating these enzymes into electrical devices because the enzymes do not form good electrical connections with fuel cell components. Currently, precious metals, such as platinum, are typically needed to perform this catalysis.

The researchers combined hydrogenase enzymes with carbon nanotubes, submicroscopic strands of pure carbon that are excellent electrical conductors. In laboratory studies, the researchers demonstrated that a good electrical connection was established using photoluminescence spectroscopy measurements. These new �biohybrid� conjugates could reduce the cost of fuel cells by reducing or eliminating the need for platinum and other costly metal components, they say.

Nano Letters: �Wiring-Up Hydrogenase with Single-Walled Carbon Nanotubes� [PDF]

Toward a new generation of �greener� consumer products

Consumers will have access to medicines, cosmetics, and other products that are �greener,� less expensive, and more environmentally friendly than ever before, thanks to new manufacturing processes now under development, according to an article scheduled for the Nov. 19 issue of Chemical & Engineering News, ACS� weekly newsmagazine.

The article, by C&EN Senior Editor Stephen K. Ritter, explains that the processes use so-called supercritical carbon dioxide, a phase of carbon dioxide with both liquid and gaseous traits and that is heralded as a nontoxic replacement for conventional manufacturing solvents. Ritter notes that while supercritical carbon dioxide shows promise for carrying out greener industrial catalytic processes, it also can provide a means for replacing inefficient chemical separations.

The new processes help reduce the use of conventional organic solvents, reduce energy consumption, and reduce the loss of costly and sometimes toxic metal catalysts. These �advances may allow for greener product separations, which typically make up the bulk of the cost of industrial processes,� Ritter states.

Chemical & Engineering News: "Designer Reactions"

Toward cancer drugs that penetrate 10 times deeper into the brain

A new drug-delivery system for cancer of the brain - one of the most difficult cancers to treat - has the potential to carry anticancer drugs 10 times deeper into tumors than conventional medications, researchers in Connecticut and New York report. Their study is scheduled for the Nov./Dec. issue of ACSďż˝ Bioconjugate Chemistry, a bi-monthly journal.

Implants with anticancer drugs inside plastic or polymer material have been used for years to treat brain tumors, which occur in people of all ages but are the leading cause of cancer-related death in patients under age 35. Although this method delivers high doses of medication to the tumor, there�s a need for a drug that penetrates deeper into the brain tissue to kill tumors. Most drugs diffuse barely a few millimeters from the implant site, the researchers say.

In the new study, Mark Saltzman and colleagues showed that linking the anticancer drug campothecin (CPT) to the polymer polyethylene glycol (PEG), increased drug diffusion to more than a centimeter from the implant site. They also identified a promising CPT-PET compound that could deliver 11 times more medication to the tumor than the plain drug alone. For patients, those advantages could substantially improve chances for successful treatment, the researchers indicate.

Bioconjugate Chemistry: "Conjugation to Increase Treatment Volume during Local Therapy: A Case Study with PEGylated Camptothecin" [PDF]

�Dragon�s blood� quenches stomach ulcer bacteria

�Dragon�s blood� may sound like an exotic ingredient in a witch�s brew or magic potion. But researchers in China are reporting that the material - which is actually a bright red plant sap used for thousands of years in traditional Chinese medicine - contains chemicals that were effective in laboratory experiments in fighting bacteria that cause millions of cases of gastrointestinal disease each year. Their study is scheduled for the current issue of ACS� Journal of Natural Products, a monthly publication.

In the new study, Weimin Zhao and colleagues indicate that �dragon�s blood� has been used for years in China and other countries as a folk remedy for stomach ulcers, blood clots, and other conditions. Researchers, however, have never identified the active ingredients in dragon�s blood responsible for its beneficial health effects on peptic ulcer and preventing blood clots.

The researchers isolated 22 different compounds from the powdered stems of Dracaena cochinchinensis, a common source of dragon�s blood. The scientists tested the compounds' effects on Helicobacter pylori (H. pylori), the bacteria known to cause most cases of stomach ulcers and gastritis. Two of the compounds blocked the growth of H. pylori. In another part of the experiment, eight other compounds from dragon's blood inhibited blood clotting, suggesting their potential use in the prevention of the blood clot responsible for some strokes and most heart attacks, the scientists say.

Journal of Natural Products: �Anti-Helicobacter pylori and thrombin Inhibitory Components from Chinese Dragon's Blood, Dracaena cochinchinensis� [PDF]

Air pollution from ship smokestacks linked to thousands of deaths annually

Smokestack emissions from ships cause tens of thousands of deaths each year in the world�s major port cities and coastal areas, according the first study on that topic, which is scheduled for the Dec. 15 issue of ACS� Environmental Science & Technology, a semi-monthly journal. The authors say that the number of deaths will continue to climb with trade growth unless remedial action is taken.

In the study, led by James J. Corbett and James J. Winebrake, the authors point out that air pollution from coal-fired electric power plants and motor vehicles has been linked to a range of adverse health effects, including asthma and heart disease. Yet no study has examined the health threats of ship emissions, even though ships emit large amounts of particulate matter into the air along coastal areas.

The researchers analyzed ship emissions� health impact, estimating global and regional mortalities by integrating global ship inventories, atmospheric models, and health impact functions. Using 2002 ship inventories, it estimated that shipping-related particulate matter emissions are responsible for about 60,000 cardiopulmonary and lung cancer deaths annually. Most of the deaths are believed to occur near coastlines in Europe, East Asia and South Asia. �Under current regulation and with the expected growth in shipping activity, we estimate that annual mortalities could increase by 40 percent by 2012,� say the authors.

Environmental Science & Technology: �Mortality from Ship Emissions: A Global Assessment� [PDF]

Breakthrough toward industrial-scale production of nanodevices

Scientists in Maryland are reporting an important advance toward the long-sought goal of industrial-scale fabrication of nanowire-based devices like ultra-sensitive sensors, light emitting diodes, and transistors for inexpensive, high-performance electronics products. The study is scheduled for the current issue of ACSďż˝ Chemistry of Materials, a bi-weekly journal.

In the report, Babak Nikoobakht points out that existing state-of-the-art assembly methods for nanowire-based devices require complicated, multi-step treatments, painstaking alignments steps, and other processing for nanowires , which are thousands of times smaller than the diameter of a human hair. The goal is to electrically address the coordinates of millions of nanowires on a surface in order to produce the components of electronic circuits. The study describes a new method in which zinc oxide nanowires are grown in the exact positions where nanodevices later will be fabricated, in a way that involves a minimum number of fabrication steps and is suitable for industrial-scale applications. �This method, due to its scalability and ease of device fabrication, goes beyond the current state-of-the-art assembly of nanowire-based devices,� the report states. �It is believed to be an attractive approach for mass fabrication of nanowire-based transistors and sensors and is expected to impact nanotechnology in fabrication of nonconventional nanodevices.�

Chemistry of Materials: �Toward Industrial-Scale Fabrication of Nanowire-Based Devices� [PDF]

Octopus and kin inspire new camouflage strategies for military applications

Researchers are studying the remarkable shape- and color-changing abilities of the octopus and its close relatives in an effort to understand one of nature�s most remarkable feats of camouflage and self-preservation. Eventually, such knowledge could lead to new and improved camouflage strategies for military applications, according to an article scheduled for the Nov. 12 issue of Chemical & Engineering News, ACS� weekly newsmagazine.

In the article, C&EN associate editor Bethany Halford points out that cephalopods, which include octopus, squid, and cuttlefish, are experts in the art of camouflage and renowned for their ability to make themselves look like fish, rocks, coral and other objects in an effort to hide from predators. By studying the various layers of skin of these creatures, particularly the chemicals in these layers that are behind their color transitions, scientists hope to develop similar camouflage strategies.

In the article, Halford describes the specialized skin cells involved in the creaturesďż˝ color transformations, including the leucophore layer, which serves as a veritable base coat, another layer with chromatophores that are filled with pigments, and yet another layer sporting iridophores that reflect light in curious ways.

Chemical & Engineering News: �Hide and Seek: Cephalopod camouflage inspires materials research�.

New fluorescent label sheds light on brain diseases

In an advance that may speed progress toward new diagnostic tests for Alzheimer�s disease (AD) and Parkinson�s disease (AD), scientists in New York are reporting development of the first direct method for measuring a key enzyme implicated in both of those chronic brain disorders. The study is scheduled for the Nov. 21 issue of ACS� Journal of the American Chemical Society, a weekly publication.

Dalibor Sames and Mary K. Froemming point out that the enzyme - 17B-HSD10 - has stirred excitement among researchers as a potential biomarker that could be used to diagnose AD and PD and chronicle the effectiveness of treatments. Other studies have found that PD patients have reduced levels of the enzyme, while increased levels seem to protect laboratory mice from the disease. 17B-HSD10 also attaches to the abnormal brain protein in AD, perhaps contributing to the loss of brain cells. �Despite the importance of this emerging physiological and pathological marker, there are no agents for direct imaging of 17B-HSD10 in living cells and tissues,� the report states.

In the new study, researchers describe development of a compound with all the required properties for serving as such an agent. In laboratory tests on human cells, they showed that the new imaging agent lit up in the presence of 17B-HSD10 to permit non-invasive, real-time monitoring of the enzyme�s activity. �This new imaging agent will be used to elucidate the biological functions of this important physiological marker,� the study reported.

Journal of the American Chemical Society: �Harnessing the Functional Plasticity of Enzymes: A Fluorogenic Probe for Imaging 17B-HSD10, an Enzyme Involved in Alzheimer�s and Parkinson�s Diseases� [PDF]

New insights into how natural antioxidants fight fat

Scientists in Taiwan are reporting new insights into why diets rich in fruits and vegetables reduce the risk of obesity. Their study focuses on healthful natural antioxidant compounds called flavonoids and phenolic acids.

In the study, Gow-Chin Yen and Chin-Lin Hsu point out that large amounts of those compounds occur in fruits, vegetables, nuts and plant-based beverages such as coffee, tea, and wine. Scientists long have known that flavonoids and phenolic acids have beneficial health effects in reducing the risk of heart attacks, cancer, obesity, and other disorders. However, there has been uncertainty about exactly how these compounds affect adipocytes, or fat cells.

The researchers studied how 15 phenolic acids and six flavonoids affected fat cells in laboratory cultures of mouse cells. Their results showed that fat cells exposed to certain antioxidants had lower levels of an enzyme that forms triglycerides and accumulated lower levels of triglycerides - fatty materials which at high levels increase the risk of heart disease. The findings suggest that these compounds could be effective in improving the symptoms of metabolic syndrome, a cluster of symptoms like obesity and high blood sugar that increase the risk of heart disease, the researchers said.

Journal of Agricultural and Food Chemistry: �Effects of Flavonoids and Phenolic Acids on the Inhibition of Adipogenesis in 3T3-L1 Adipocytes� [PDF]

A faster, more sensitive method for detecting anthrax

Amid continuing concerns that anthrax might be used as a bioterrorism weapon, government researchers report development of a faster, more sensitive blood test for detecting the deadly toxins produced by the anthrax bacterium, Bacillus anthracis. The test produces results in only 4 hours and could save lives by allowing earlier detection of infection, they say. Their study is scheduled for publication in the Nov. 22 issue of ACSďż˝ Analytical Chemistry, a semi-monthly journal.

Standard identification of anthrax (Bacillus anthracis) infection relies on a combination of time-consuming steps, including cell culture and gene amplification, which can take several days to provide a diagnosis and have limitations for detecting early stages of infection. Early diagnosis is critical for effective treatment of pulmonary or inhalation anthrax, the most deadly form.

John R. Barr and colleagues in a multi-center team effort used a form of mass spectrometry to detect the presence of �lethal factor,� the key toxin produced by the anthrax bug, in the blood of monkeys with inhalation anthrax. The method took only four hours to identify the toxin and detected it at very low levels, demonstrating its potential for early detection of infection, the researchers say. The new method also shows promise as a research tool for providing a better understanding of the anthrax infection cycle and for evaluating the effectiveness of different therapies and methods to fight infections.

Analytical Chemistry: �Detection and Quantification of Anthrax Lethal Factor in Serum by Mass Spectrometry� [PDF]

Medical plastics industry on the rebound

In the wake of Dow Corning�s bankrupting experience with silicone gel breast implants, the medical plastics industry is now undergoing a renaissance. Medical plastics are a $1 billion a year market and demand is growing at 10 to 20 percent a year. Driving this growth are the demands of an aging population for implantable medical devices, such as artificial hips and knees, according to an article of the November 5 issue of Chemical & Engineering News, ACS� weekly newsmagazine.

The demand continues to rise for devices incorporating plastics such as artery-opening stents, heart pacemakers, and other products that improve quality of life for an aging population. To meet this growing need, medical device makers are creating new types of implants with novel properties, writes C&EN senior correspondent Marc S. Reisch. New legal protections for plastic material makers that weren�t available a decade ago also fuel the industry�s growth, he notes.

In the article, Reisch interviews both new and established companies about the current state of the medical plastics industry. He finds that some larger companies are still reluctant to enter the medical device market because of its potential legal risks, while some smaller companies are aggressively forging ahead to tap into its promises. Others see great opportunities in providing the raw materials for making the devices without becoming directly involved in their manufacture. Nevertheless, the medical plastics industry appears to be on a big rebound.

Chemical & Engineering News: �Medical polymers renaissance�

Government plan to revive �Dead Zone� in Gulf of Mexico could backfire

The potential revision to the government�s approach for rejuvenating a huge �Dead Zone� in the Gulf of Mexico is potentially dangerous and should be reconsidered, scientists in Michigan are reporting in a study scheduled for the Dec. 1 issue of ACS� Environmental Science & Technology, a semi-monthly journal.

In the study, Donald Scavia and Kristina A. Donnelly point out that the Gulf of Mexico has one of the largest hypoxic, or oxygen-depleted, areas in the world. Fish and plants in this 6,000 square mile �Dead Zone� have been devastated, leaving the waters incapable of sustaining many types of aquatic life. In response, an intergovernmental task force gave the U. S. Congress and the President a so-called Hypoxia Action Plan in 2001, which aimed to reduce the size of the Dead Zone. That original plan called for reducing nitrogen loads to the Gulf, but recent assessments are considering phosphorous as the limiting factor in controlling the algae blooms that deplete oxygen from the Gulf water, and focusing on reducing sewage discharges and other inputs of phosphorous.

The new study concluded that pollution control efforts must continue to focus on nitrogen even if phosphorus controls are added. It found that a phosphorus-only approach is potentially dangerous. Using mathematical model estimates and real-world data from other hypoxia reduction experiences in North Carolina and Hong Kong waters, the researchers suggest that a phosphorous-only approach could possibly enlarge the Dead Zone, extending it into the western portion of the Gulf. �The prudent approach would be to address both nitrogen and phosphorous,� the researchers said.

Environmental Science & Technology: �Reassessing Hypoxia Forecasts for the Gulf of Mexico� [PDF]