Tuesday, April 5, 2011

Mimicking Mother Nature yields promising materials for drug delivery, other applications

Mimicking Mother Nature's genius as a designer is one of the most promising approaches for developing new medicines, sustainable sources of food and energy, and other products that society needs to meet the great challenges that lie ahead in the 21st century, a noted scientist said here today.

In the inaugural Kavli Foundation Innovations in Chemistry Lecture at the 241st National Meeting & Exposition of the American Chemical Society, Virgil Percec, Ph.D., said the approach — often termed "bioinspired design" — can stake a claim to becoming one of the most innovative fields in science.

"Using Nature as a model and mentor offers great promise for developing new commercial products, launching new industries, and for basic progress in science and technology," Percec said. "Nature already has found simple, elegant, sustainable solutions to some of our most daunting problems. The models are there — the leaf as the perfect solar cell, for instance — waiting for us to fathom and mimic."

Percec's laboratory at the University of Pennsylvania led an international collaboration of scientists to prepare a library of synthetic biomaterials that mimic the cell membrane, the biological films that hold the contents of the 50 trillion cells in the human body. Composed of mainly of proteins and fats, cell membranes have a crucial role in controlling the flow of nutrients and chemical signals into cells and the exit of substances produced inside cells.

The scientists found that when certain organic substances called Janus dendrimers are added to water, they spontaneously form a menagerie of nano-sized packets shaped like bubbles, tubes, and disks. Percec named them "dendrimersomes," and indications are that the structures are ideally suited to serve as packages for carrying drugs, genes, medical imaging and diagnostic agents, and cosmetics into the body. Their structural similarity to natural cell membranes makes them highly compatible with the body's own cells.

Dendrimersomes show promise of being more stable, targeted, and effective than existing nanomaterials used for drug delivery, Percec said. The packets also tend to be uniform in size, are easily formed, and can be customized for different functions, properties which give them additional advantages in the emerging field of nanomedicine.

Percec's talk will describe dendrimersomes and other bioinspired , some of which show promise for improved solar cells, electronics, water purification, and other applications. It takes place on Monday, March 28, from 5:30 to 6:30 p.m., Pacific Time, in the Anaheim Convention Center, Halls D/E.

Sponsored by The Kavli Foundation, a philanthropic organization that supports basic scientific research, the lectures are designed to address the urgent need for vigorous, "outside the box" thinking by scientists as they tackle the world's mounting challenges, including climate change, emerging diseases, and water and energy shortages.

"We are dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research, and supporting scientists and their work," said Kavli Foundation President Robert W. Conn in a statement. "The Kavli Foundation Innovations in Chemistry Lecture program at the ACS national meetings fits perfectly with our commitment to support groundbreaking discovery and promote public understanding."

More information: The Kavli lectures debut at the Anaheim meeting during this International Year of Chemistry and will continue through 2013. They will address the urgent need for vigorous, new, "outside-the-box"- thinking, as scientists tackle many of the world's mounting challenges like climate change, emerging diseases, and water and energy shortages. The Kavli Foundation, an internationally recognized philanthropic organization known for its support of basic scientific innovation, agreed to sponsor the lectures in conjunction with ACS in 2010.

Provided by American Chemical Society (news : web)

The way to (kill) a bug's heart is through its stomach

A study at Michigan State University has revealed a potential new way for plants to fend off pests – starvation.

Gregg Howe, biochemistry and molecular biology professor, cites that this defense mechanism is just one example of a veritable evolutionary arms race between and herbivores.

Howe, in the current issue of the Proceedings of the National Academy of Sciences, offers insights to understanding the chemical weaponry of this war, which could lead to new approaches to protect crops.

All plants produce the enzyme threonine deaminase, or TD1. Howe's research focused on potato and tomato plants, which also have the ability to produce a closely related enzyme TD2 when attacked by caterpillars. Rather than repel caterpillars, however, TD2's devastating effects come later – in the pests' stomachs. TD2 goes to work in the gut of caterpillars to degrade threonine, a key nutrient they need to grow. In essence, the plant actively starves the caterpillar.

The battle sees plants continually developing chemical defenses to fend off their herbivore adversaries' ever-adapting arsenal, said Howe, who co-authored the paper with Eliana Gonzales-Vigil, visiting research associate in MSU's horticulture department.

"The arms-race paradigm is quite important for explaining plant chemical diversity and interactions between plants and herbivores in general," he said. "Unfortunately, our understanding of the molecular evolution of chemical defensive traits is still in its infancy."

What the young research has revealed already, however, is that the ability of TD2 to break down threonine is activated only after it enters the insect's gut in the form of a chewed up leaf. The capacity of TD2 as a defense against pests was bolstered when the research team identified the enzyme's x-ray crystal structure. Seeing that it had a more stable structure and is more resilient than TD1 or other TDs, suggests that the enzyme is a key that could lead to new forms of pesticides, Howe said.

"This confirms a role for gene duplication in the evolution of plant defenses that target the digestive process of insects," he said. "It represents a novel approach to protecting plants against ."

Provided by Michigan State University (news : web)

Imaging the paintings under the paintings of the Old Masters

Gaze upon Rembrandt's The Night Watch, The Storm on the Sea of Galilee, or one of the great Dutch master's famous self-portraits. Contemplate Caravaggio's Boy with a Basket of Fruit, Supper at Emmaus, or the famed Italian artist's Seven Works of Mercy. Admire Peter Paul Rubens' Prometheus Bound, Portrait of Władysław IV, or the Flemish baroque painter's The Exchange of Princesses.

Speaking at the 241st National meeting & Exposition of the American Chemical Society, an international team of scientists today described use of a new technique to see the paintings under the paintings of Rembrandt, , Rubens, and other 17th Century Old Master painters. The report by scientists in Belgium, The Netherlands and the United States was among almost two dozen studies presented as part of a symposium on chemistry and art titled "Partnerships and New Analytical Methodologies at the Interface of Chemistry and Art."

"The underpainting was the first and most important step in creating a work of art," explained lead scientist Matthias Alfeld, who is with the University of Antwerp in Belgium. "It was the sketch that guided the artist through the creative process. The Old Masters generally used to roughly indicate light, shade and contours. Observation of the underpainting would allow us to see the first execution of the artist's vision of the painting. It's a more detailed look over the shoulder of the artist at work. But the underpainting has virtually escaped all imaging efforts. So far, our methods to visualize the underpainting, except in localized cross sections, have been very limited."

Alfeld and colleagues described use of a powerful new technique called scanning macro X-ray fluorescence analysis that allows more detailed imaging of the composition of underpaintings. It is portable enough for use on-the-scene in museums and does not harm priceless artwork. The technology already has provided new insights into the nature of the paint that some Old Masters used in their underpainting.

An analysis of paintings from the workshops of and Caravaggio, for instance, led them to the conclusion that the Old Masters were more frugal than fussy about the paint used for the underpainting. The analysis suggested that this brown pigment mixture in underpaintings actually consisted of recycled leftovers from the artist scraping his palette clean.

"Using the new technique, we hope to disperse doubts about the authenticity of several paintings or to confirm that these were not by the painter they have been attributed to," Alfeld said. "It is nice to show that the world of art can intersect with chemistry. Chemistry is such an all-encompassing science. Imagine, chemistry isn't just about molecules and reactions, but it also involves also the study of something as beautiful as great works of art."

Among the reports scheduled for the symposium are:

Lisa Gulian, Ph.D., of University of California-Santa Barbara, reports methods to optimize REMPI laser mass spectrometry as a new analytical tool to archaeology using theobromine and caffeine as molecular markers in Mesoamerican pottery and is expanding this approach to the field of art to examine laccaic acid in shellacs. REMPI laser mass spectrometry is a combination of resonance enhanced multi photon ionization spectroscopy and time of flight mass spectrometry.

Jennifer Mass, Ph.D., Winterthur, Conservation Department, Winterthur, Del., examined Matisse's iconic and controversial work, Le Bonheur de vivre (The Joy of Life, 1905-1906, The Barnes Foundation) to identify the origin of the fading, discoloration, and flaking of the yellow paints. An XRF map of the work demonstrated that the painting was executed with both chrome yellow (PbCrO4) and cadmium yellow (CdS) pigments, but that the discoloration and flaking are confined to the regions painted with cadmium yellow. Microsamples of the cadmium yellow paints were examined by XANES, XPS, FTIR, and Raman spectroscopies to identify evidence of photo-oxidative degradation.

R. Graham Cooks, Ph.D., of Purdue University, West Lafayette, Ind., presents a study on the ethos of the group — whether in science or in art — deeply engaged in a mixed communal and individual activity that involves physical materials as well as conceptual developments. It deals with matter and spirit, sharing and competing, bursts of self-doubt and creativity. A group of 1848-inspired artists from 19th Century England (Holman Hunt, D. G. Rossetti and John Millais) is introduced, their work is described and comparisons are made with the 1968-inspired generation of mass spectroscopists whose trials and triumphs helped launch one of the great subjects in science.

Nicholas P Bigelow, Ph.D., University of Rochester, Rochester, N.Y., describes the recently launched SCIART-NSF project. The goal is to apply the 21st Century's most advanced nanotechnology and chemical/material science research techniques to the 19th Century's serendipitous nanotechnology, the
daguerreotype. Recently observations have revealed that there is alarming deterioration occurring with daguerreotypes, which is addressed . Also described is the application of high-resolution microscopy and other nano-material science techniques to understanding of the fundamental character of the daguerreotype and its degradation.

Provided by American Chemical Society (news : web)

Advance toward making biodegradable plastics from waste chicken features

In a scientific advance literally plucked from the waste heap, scientists today described a key step toward using the billions of pounds of waste chicken feathers produced each year to make one of the more important kinds of plastic. They described the new method at the 241st National Meeting & Exposition of the American Chemical Society, being held here this week.

"Others have tried to develop thermoplastics from feathers," said Yiqi Yang, Ph.D., who reported on the research. "But none of them perform well when wet. Using this technique, we believe we're the first to demonstrate that we can make chicken-feather-based thermoplastics stable in water while still maintaining strong mechanical properties."

Thermoplastics are one of two major groups of , and include nylon, polyethylene, polystyrene, polyvinyl chloride, and dozens of other kinds. They are used to make thousands of consumer and industrial products ranging from toothbrush bristles to soda pop bottles to car bumpers. Thermoplastics got that name because they need heat (or chemicals) to harden from a liquid into a final shape, and can be melted and remolded time and again. The other group, thermosetting plastics, harden once and can't be remelted again.

Yang pointed out that both kinds of plastics are made mainly from ingredients obtained from oil or natural gas. Because of concerns about petroleum supplies, prices, and sustainability, dozens of scientific teams are working to find alternative ingredients. One major goal is to use agricultural waste and other renewable resources to make bioplastics that have an additional advantage of being biodegradable once discarded into the environment.

"We are trying to develop plastics from renewable resources to replace those derived from petroleum products," said Yang, who is an authority on biomaterials and biofibers in the Institute of Agriculture & Natural Resources at the University of Nebraska-Lincoln. "Utilizing current wastes as alternative sources for materials is one of the best approaches toward a more sustainable and more environmentally responsible society."

Chicken feathers are an excellent prospect, Yang explained, because they are inexpensive and abundant. Few shoppers think about it, but every shrink-wrapped broiler in the supermarket cooler leaves behind a few ounces of feathers. Annually there are more than 3 billion pounds of waste chicken feathers in the United States alone. These feathers can be processed into a low-grade animal feed, but that adds little value to the feathers and may also cause diseases in the animals. All too often, they become a waste disposal/environmental pollution headache, incinerated or stored in landfills.

Yang explained that chicken feathers are made mainly of keratin, a tough protein also found in hair, hoofs, horns, and wool that can lend strength and durability to plastics. Yang added that the mechanical properties of feather films outperform other biobased products, such as modified starch or plant proteins.

To develop the new water-resistant thermoplastic, Yang and colleagues processed with chemicals, including methyl acrylate, a colorless liquid found in nail polish that undergoes polymerization — that's the process used in producing plastics in which molecules link together one by one into huge chains. This process resulted in films of what Yang's group terms "feather-g-poly(methyl acrylate)" plastic. It had excellent properties as a thermoplastic, was substantially stronger and more resistant to tearing than plastics made from soy protein or starch, and as a first among chicken-feather plastics had good resistance to water.

Provided by American Chemical Society (news : web)

NIST, ASTM land a one-two punch to fight explosives terrorism

 Trace-explosives detectors (TEDs) are an increasingly common sight at airports and on loading docks, and emergency response personnel carry them to evaluate suspicious packages. A new test material developed by the National Institute of Standards and Technology (NIST) in cooperation with ASTM International enables users of these products to evaluate their performance and reliability.

The new testing material, NIST Standard Reference Material (SRM) 2906, Trace Explosives Calibration Solutions, was designed to meet the specifications of ASTM E 2520-07, Standard Practice for Verifying Minimum Acceptable Performance of Trace Explosive Detectors. ASTM is one of the leading industrial organizations for the development of voluntary consensus standards.

The NIST reference material contains calibration solutions of three high explosives: RDX (an ingredient in Composition C-4), PETN, and TNT. Under the test protocol, users sequentially apply a single drop of explosive solution and a solvent blank to swipes, the solvents are allowed to evaporate, and the instrument is tested. A simple ‘yes-no’ alarm checklist is used to determine TED performance.

SRM 2906 includes four ampoules of each of the three explosives and a blank along with a dropper bottle for each. NIST researchers formulated the concentrations of these solutions to be near, but above, the detection limit of commercial swipe-type detectors, which are commonly based on ion mobility spectrometry. When tested with the solutions, properly functioning TEDs should provide an alarm response.

This SRM fully satisfies the need for independent test materials with low uncertainties in concentrations necessary for reliable TED evaluation. Equipment vendors may use the SRM to improve and optimize their designs and demonstrate to their customers how well their machines function. Buyers may use the SRM to make sound procurement decisions. The combination of a validated standard practice and SRM will provide TED users with a reliable means of verifying initial and continuing field performance of their equipment, contributing to the fight against explosives terrorism.

More information: http://www.nist.go … rm/index.cfm

Provided by National Institute of Standards and Technology (news : web)

'Bacterial dirigibles' emerge as next-generation disease fighters

Scientists today reported development of bacteria that serve as mobile pharmaceutical factories, both producing disease-fighting substances and delivering the potentially life-saving cargo to diseased areas of the body. They reported on this new candidate for treating diseases ranging from food poisoning to cancer — termed "bacterial dirigibles" -- at the 241st National Meeting & Exposition of the American Chemical Society, being held here.

"We're building a platform that could allow bacterial dirigibles to be the next-generation disease fighters," said study leader William E. Bentley, Ph.D. "The concept is unique."

Bentley explained that traditional genetic engineering reprograms bacteria so that they produce antibiotics, insulin, and other medicines and materials. The bacteria grow in nutrient solutions in enormous stainless steel vats in factories. They release antibiotics or insulin into vats, and technicians harvest the medicine for processing and eventual use in people.

The bacterial dirigible approach takes bioengineering a step further. Scientists genetically modify bacteria to produce a medicine or another disease-fighting substance. Then, however, they give the bacteria a biochemical delivery address, which is the locale of the disease. Swallowed or injected into the body, the bacteria travel to the diseased tissue and start producing substances to fight the disease.

Bentley chose the term "bacterial dirigibles" because the modified bacteria actually have the fat-cigar look of blimps and zeppelins, those famous airships of yesteryear. In addition, the bacteria seem to float like a blimp as they make deliveries.

The prototype bacterial dirigible is a strain of E. coli that Bentley and colleagues developed at the University of Maryland in College Park, where he is Robert E. Fischell Distinguished Professor and Chair of the Fischell Department of Bioengineering.

"We have created a genetic circuit that endows E. coli with targeting, sensing and switching capabilities," Bentley explained. "The resultant cell is a bacterial dirigible – a cell that autonomously navigates and carries or deploys important 'cargo'."

The "targeting" molecule is attached to the outer surface of the bacteria. It gives the bacteria an ability to "hone in" on specific cells and attach to them — in this instance, the intestinal cells where other strains of E. coli cause food poisoning symptoms. Inside the bacteria is a gene segment that acts as "nanofactory." It uses the bacteria's natural cellular machinery to make drugs, such as those that can fight bacterial infections, viruses, and .

The nanofactory also could produce signaling molecules that enable the dirigible to communicate with natural bacteria at the site of an infection. Some bacteria engage in a biochemical chit-chat, termed "quorum sensing," in which they coordinate the activities needed to establish an infection. Bacteria dirigibles could produce their own signaling molecules that disrupt quorum sensing, preventing bacteria from starting an infection.

In work on the prototype, Bentley's group showed that the re-engineered strain of E. coli did seek out and attach to intestinal cells growing in laboratory cultures. They also showed that the modified bacteria did produce chemical signals that triggered neighboring bacteria to make certain proteins that they don't normally produce. The results constitute proof of principle that the "bacterial dirigibles" concept can work, he said.

Using this approach, the nanofactory also could produce chemical signals that trigger cells lining the stomach or other parts of body to synthesize natural disease-fighting substances, such as immunoglobulins. Immunoglobulins are proteins used by the immune system to identify and destroy foreign objects, such as bacteria and viruses.

"The bacterial dirigibles can send out a strong signal to which disease-fighting cells of the body can respond," Bentley noted. "The chemical signals tell the cells to attack the body's foreign invaders, including the that cause food poisoning."

Bacterial dirigibles could be given to patients in the form of probiotics, live microorganisms that are beneficial to health like those found in certain kinds of yogurt, Bentley said. Doctors could also inject dirigibles into the bloodstream or directly into a diseased area, such as a tumor, he said.

Provided by American Chemical Society (news : web)

Updating the Mary Poppins solution with a better bitter blocker

With millions of adults and children avoiding nutritious foods because of the bitter taste, and gagging or vomiting when forced to take bitter liquid medicines, scientists today reported an advance toward a high-tech version of Mary Poppins' solution. It's not a spoonful of sugar to help the stuff go down, they reported at the 241st National Meeting & Exposition of the American Chemical Society (ACS), but a new and improved "bitterness blocker."

"A lot of people are very sensitive to bitter taste in medicines, calorie-free sweeteners, and foods," said Ioana Ungureanu, who described the new substance at the ACS meeting, one of the largest scientific conferences of 2011. "We'd like to be able to make their diets more enjoyable by masking the off-putting flavors of bitterness. Blocking these flavors we call off-notes could help consumers eat healthier and more varied diets. It could encourage them to switch to non-calorie soft drinks and help children and seniors swallow bitter-tasting medications."

Ungureanu, a research scientist with Givaudan Flavors Corporation in Cincinnati, Ohio noted, for instance, that green, leafy vegetables like spinach and broccoli are excellent sources of calcium and other nutrients important for good health. But calcium, magnesium, zinc and other key minerals and vitamins in unfortunately have a taste that people find unpleasantly bitter. Though it is unlikely that the bitterness of these fresh vegetables will be masked any time soon, there are many other food and beverage products that are becoming much more palatable.

Taste cells with specific receptors blanket the tongue. Scientists have identified 27 receptors for different shades of bitterness, which along with salty, sweet, sour and savory (or umami), make up the human taste palate. The new bitterness blocker, known only at this point as GIV3616, works by blocking some of the bitterness receptors.

Givaudan scientists previously discovered the first commercially feasible substance capable of blocking in humans. Called GIV3727, it inhibited taste receptors involved in people's ability to detect the bitter aftertaste from artificial sweeteners, including saccharin and sucralose. But Givaudan scientists immediately realized that it could be used as the model for developing blockers for other taste receptors, including substances that might make liquid medicines or bitter foods more palatable.

The new compound, Ungureanu said, is more potent and can dissolve more quickly in foods and beverages. "It works at levels on the order of parts per million and blocks flavors using 10 times less material than what was needed previously."

"Sensitivity to many foods is partly due to genetics," Ungureanu said. "Recent studies have estimated that a large portion of the population — almost 25 percent, or 75 million people — are known as supertasters who have heightened sensitivity to bitter foods. "Our compound could one day make supertasters' coffee more smooth or their veggies more appetizing."

The discovery of compounds like GIV3727 and GIV3616 is part of an ongoing revolution in research on flavors and taste. In the past, the food and drug industry relied on salt, fat, and sugar to hide bitterness and other unpleasant flavors. But concerns about the health effects of those three ingredients have shifted the focus. Instead of hiding unpleasant tastes, chemists, molecular biologists and other scientists are developing ways to change how the tongue senses tastes.

Givaudan Flavours is a trusted partner to the world's leading food and beverage companies, combining its global expertise in sensory understanding and analysis and consumer-led innovation in support of unique product applications and new market opportunities. From concept to store shelves and quick serve restaurants, Givaudan works with food and beverage manufacturers to develop flavors and tastes for market leading products across five continents.

Provided by American Chemical Society (news : web)