Saturday, April 2, 2011

Mimicking Mother Nature yields promising materials for drug delivery and 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 recently said.

In the inaugural Kavli Foundation Innovations in Chemistry Lecture on March 29 at the 241st National Meeting & Exposition of the American Chemical Society in Anaheim, California, 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.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Chemical Society.

Microreactors: Small scale chemistry could lead to big improvements for biodegradable polymers

 Using a small block of aluminum with a tiny groove carved in it, a team of researchers from the National Institute of Standards and Technology (NIST) and the Polytechnic Institute of New York University is developing an improved "green chemistry" method for making biodegradable polymers. Their recently published work is a prime example of the value of microfluidics, a technology more commonly associated with inkjet printers and medical diagnostics, to process modeling and development for industrial chemistry.

"We basically developed a microreactor that lets us monitor continuous polymerization using enzymes," explains NIST materials scientist Kathryn Beers. "These enzymes are an alternate green technology for making these types of polymers -- we looked at a polyester -- but the processes aren't really industrially competitive yet," she says. Data from the microreactor, a sort of zig-zag channel about a millimeter deep crammed with hundreds of tiny beads, shows how the process could be made much more efficient. The team believes it to be the first example of the observation of polymerization with a solid-supported enzyme in a microreactor.

The group studied the synthesis of PCL,* a biodegradable polyester used in applications ranging from medical devices to disposable tableware. PCL, Beers explains, most commonly is synthesized using an organic tin-based catalyst to stitch the base chemical rings together into the long polymer chains. The catalyst is highly toxic, however, and has to be disposed of.

Modern biochemistry has found a more environmentally friendly substitute in an enzyme produced by the yeast strain Candida antartica, Beers says, but standard batch processes -- in which the raw material is dumped into a vat, along with tiny beads that carry the enzyme, and stirred -- is too inefficient to be commercially competitive. It also has problems with enzyme residue contaminating and degrading the product.

By contrast, Beers explains, the microreactor is a continuous flow process. The feedstock chemical flows through the narrow channel, around the enzyme-coated beads, and, polymerized, out the other end. The arrangement allows precise control of temperature and reaction time, so that detailed data on the chemical kinetics of the process can be recorded to develop an accurate model to scale the process.

"The small-scale flow reactor allows us to monitor polymerization and look at the performance recyclability and recovery of these enzymes," Beers says. "With this process engineering approach, we've shown that continuous flow really benefits these reactors. Not only does it dramatically accelerate the rate of reaction, but it improves your ability to recover the enzyme and reduce contamination of the product." A forthcoming follow-up paper, she says, will present a full kinetic model of the reaction that could serve as the basis for designing an industrial scale process.

While this study focused on a specific type of enzyme-assisted polymer reactions, the authors observe, "it is evident that similar microreactor-based platforms can readily be extended to other systems; for example, high-throughput screening of new enzymes and to processes where continuous flow mode is preferred."

* Polycaprolactone

Story Source:

The above story is reprinted (with editorial adaptations  from materials provided by National Institute of Standards and Technology (NIST).

Journal Reference:

Santanu Kundu, Atul S. Bhangale, William E. Wallace, Kathleen M. Flynn, Charles M. Guttman, Richard A. Gross, Kathryn L. Beers. Continuous Flow Enzyme-Catalyzed Polymerization in a Microreactor. Journal of the American Chemical Society, 2011; : 110325123921095 DOI: 10.1021/ja111346c


54 beneficial compounds discovered in pure maple syrup

University of Rhode Island researcher Navindra Seeram has discovered 34 new beneficial compounds in pure maple syrup and confirmed that 20 compounds discovered last year in preliminary research play a key role in human health.

On March 30 at the 241st American Chemical Society's National Meeting in Anaheim, Calif. the URI assistant pharmacy professor is telling scientists from around the world that his URI team has now isolated and identified 54 beneficial compounds in pure maple syrup from Quebec, five of which have never been seen in nature.

"I continue to say that nature is the best chemist, and that maple syrup is becoming a champion food when it comes to the number and variety of beneficial compounds found in it," Seeram said. "It's important to note that in our laboratory research we found that several of these compounds possess anti-oxidant and anti-inflammatory properties, which have been shown to fight cancer, diabetes and bacterial illnesses."

These discoveries of new molecules from nature can also provide chemists with leads that could prompt synthesis of medications that could be used to fight fatal diseases, Seeram said.

"We know that the compounds are anti-inflammatory agents and that inflammation has been implicated in several chronic diseases, such as heart disease, diabetes, certain types of cancers and neurodegenerative diseases, such as Alzheimer's," Seeram said.

As part of his diabetes research, Seeram has collaborated with Chong Lee, professor of nutrition and food sciences in URI's College of the Environment and Life Sciences. The scientists have found that maple syrup phenolics, the beneficial anti-oxidant compounds, inhibit two carbohydrate hydrolyzing enzymes that are relevant to Type 2 diabetes management.

The irony of finding a potential anti-diabetes compound in a sweetener is not lost on Seeram. "Not all sweeteners are created equal," he said.

Among the five new compounds is Quebecol, a compound created when a farmer boils off the water in maple sap to get maple syrup. It takes 40 liters (10.5 gallons) of sap to make 1 liter (2 pints) of syrup.

"Quebecol has a unique chemical structure or skeleton never before identified in nature," Seeram said. "I believe the process of concentrating the maple sap into maple syrup is what creates Quebecol. There is beneficial and interesting chemistry going on when the boiling process occurs. I believe the heat forms this unique compound."

Seeram said he and his team chose the common name of Quebecol for the new compound to honor the province of Quebec in Canada, which leads the worldwide production of maple syrup. Seeram's research was supported by the

Conseil pour le developpement de l'agriculture du Quebec (CDAQ) and Agriculture and Agri-Food Canada (AAFC) on behalf of the Canadian maple syrup industry.

"Producers, transformers and partners of the Canadian maple industry believe that investing in maple syrup knowledge and innovation will bring the products to another level in a few years," said Serge Beaulieu, president of the Federation of Quebec Maple Syrup Producers and member of the Canadian Maple Industry Advisory Committee.

"Quebec Maple Syrup Producers are especially proud to be leading this long-term innovative strategy on behalf of the Canadian industry and with the talented scientists of the Canadian Maple Innovation Network."

Genevieve Beland, marketing director of the Federation added, "Maple products' composition is unique and we are at the starting point of a new era. Ten years from now consumers will appreciate 100 percent pure maple products because they are delicious, natural and have a number of healthy compounds."

"As we continued our research in the past year, we were astonished when the number of beneficial compounds that we isolated is now more than double the original amount," said Seeram, who is now releasing his findings.

Seeram is the organizer of the daylong symposium on "Bioactives in Natural Sweeteners," and is joined by scientists from Canada, Japan, Mexico and the United States to discuss natural sweeteners. Seeram's collaborations with Angela Slitt, assistant professor of biomedical sciences in URI's College of Pharmacy and Professor Lee, will also be presented during the meeting.

Seeram's findings will be detailed in his article recently accepted for publication in the Journal of Functional Foods. The title of the paper is "Quebecol, a novel phenolic compound isolated from Canadian maple syrup." In addition, Seeram and Lee's work on diabetes and maple syrup will also be published in an upcoming edition of the Journal of Functional Foods.

"I can guarantee you that few, if any, other natural sweeteners have this anti-oxidant cocktail of beneficial compounds; it has some of the beneficial compounds that are found in berries, some that are found in tea and some that are found in flaxseed. People may not realize it, but while we have a wide variety of fruits and vegetables in our food chain, maple syrup is the single largest consumed food product that is entirely obtained from the sap of trees," Seeram said.

Reiterating a statement he made last year, Seeram said no one is suggesting that people consume large quantities of maple syrup, but that if they are going to use a sweetener on their pancakes, they should choose pure maple syrup and not the commercial products with high fructose corn syrup.

"Pure maple syrup is not only delicious, it is so much better for you," Seeram said.

Funding of CDAQ is provided through Agriculture and Agri-Food Canada's Advancing Canadian Agriculture and Agri-Food program. AAFC has been able to provide financial support for maple syrup research through the program 'Growing Canadian Agri-Innovations'.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Rhode Island.

Creating the perfect Bloody Mary: Good chemistry of fresh ingredients

After tackling the chemistry of coffee, tea, fruit juices, soda pop, beer, wine and other alcoholic beverages, why not take on the ultimate challenge, the Mount Everest of cocktails, what may be the most chemically complex cocktail in the world, the Bloody Mary? And in this the International Year of Chemistry (IYC), why not include its global offspring, the International Mary?

Those challenges underpin a presentation on March 29 reviewing the Bloody Mary's composition and the taste sensations created by those ingredients at the 241st National Meeting & Exposition of the American Chemical Society (ACS), being in Anaheim, California.

"It's a very complicated drink," said Neil C. Da Costa, Ph.D., a expert on the chemical analysis of flavors at International Flavors & Fragrances, Inc., Union Beach, N.J. "The Bloody Mary has been called the world's most complex cocktail, and from the standpoint of flavor chemistry, you've got a blend of hundreds of flavor compounds that act on the taste senses. It covers almost the entire range of human taste sensations -- sweet, salty, sour and umami or savory -- but not bitter."

Da Costa said those flavors originate in the basic ingredients in the traditional Bloody Mary, which by one account originated in a Paris bar in the 1930's. Stories link the name to various historical figures, especially Queen Mary I of England, noted for her bloody repression of religious dissenters. The ingredients include tomato juice, Worcestershire and Tabasco sauce, fresh lemon or lime juice, horseradish, black pepper, and celery salt. Shaken with ice or served over ice, it is often garnished with celery and a lemon wedge.

"Most of the ingredients have been analyzed for their key flavor volatiles, the chemicals that can evaporate from the glass and produce the aroma," Da Costa explained. "Similarly for the non-volatiles, which are the chemicals that stay in the liquid and contribute toward the flavor there. My presentation reviews the composition of these ingredients and highlights the key components and their sensory attributes."

Some of the ingredients have been linked with beneficial health effects, Da Costa, noted, citing the rich source of lycopene, for instance, in the tomato juice; horseradish with its allyl isothiocyanate, which can be effective at lower concentrations; other phytochemicals in lemon; and even the alcohol in vodka, which some studies suggest can be beneficial when taken occasionally in small amounts.

Does Da Costa's research provide any insights for making a good Bloody Mary? He cites several:

Make it fresh. Chemically, the Bloody Mary is a "highly unstable" concoction, and the quality tends to deteriorate quickly.Ice it up. Serving Bloody Marys on ice helps to slow down the chemical reactions involving acids in tomato juice and other ingredients that degrade the taste.Mind your mixes. If you use a cocktail mix, add some fresh ingredients to enhance the flavor and aroma.Splurge on the juice. Tomato juice makes up most of the Bloody Mary's volume, so use high quality juice that has a deep, rich flavor.Economize on the vodka. The intense, spicy flavor of a Bloody Mary masks the vodka, and using premium vodka makes little sense.

In the spirit of the IYC, Da Costa discussed the variations on the Bloody Mary consumed in other parts of the world. These "International Marys" include Denmark's Danish Mary; the Highland Mary (a.k.a. the Bloody Scotsman); the Russian Mary; the Bloody Geisha (yes, that's sake instead of vodka); the Bloody Maureen (replace vodka with Guinness); and the Bloody Molly (Irish whiskey replaces vodka).

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by American Chemical Society.

Smooth single-molecule layers of materials: Expanding the degrees of surface freezing

As part of the quest to form perfectly smooth single-molecule layers of materials for advanced energy, electronic, and medical devices, researchers at the U.S. Department of Energy's Brookhaven National Laboratory have discovered that the molecules in thin films remain frozen at a temperature where the bulk material is molten. Thin molecular films have a range of applications extending from organic solar cells to biosensors, and understanding the fundamental aspects of these films could lead to improved devices.

The study, which appears in the April 1, 2011, edition of Physical Review Letters, is the first to directly observe "surface freezing" at the buried interface between bulk liquids and solid surfaces.

"In most materials, you expect that the surface will start to disorder and eventually melt at a temperature where the bulk remains solid," said Brookhaven physicist Ben Ocko, who collaborated on the research with scientists from the European Synchrotron Radiation Facility (ESRF), in France, and Bar-Ilan University, in Israel. "This is because the molecules on the outside are less confined than those packed in the deeper layers and much more able to move around. But surface freezing contradicts this basic idea. In surface freezing, the interfacial layers freeze before the bulk."

In the early 1990s, two independent teams (one at Brookhaven) made the first observation of surface freezing at the vapor interface of bulk alkanes, organic molecules similar to those in candle wax that contain only carbon and hydrogen atoms. Surface freezing has since been observed in a range of simple chain molecules and at various interfaces between them.

"The mechanics of surface freezing are still a mystery," said Bar Ilan scientist Moshe Deutsch. "It's puzzling why alkanes and their derivatives show this unusual effect, while virtually all other materials exhibit the opposite, surface melting, effect."

In the most recent study, the researchers discovered that surface freezing also occurs at the interface between a liquid and a solid surface. In a temperature-controlled environment at Brookhaven's National Synchrotron Light Source and the ESRF, the group made contact between a piece of highly polished sapphire and a puddle of liquid alkanol -- a long-chain alcohol. The researchers shot a beam of high-intensity x-rays through the interface and by measuring how the x-rays reflected off the sample, the group revealed that the alkanol molecules at the sapphire surface behave very differently from those in the bulk liquid.

According to ESRF scientist Diego Pontoni, "Surprisingly, the alkanol molecules form a perfect frozen monolayer at the sapphire interface at temperatures where the bulk is still liquid." At sufficiently high temperatures, about 30 degrees Celsius above the melting temperature of the bulk alkanol, the monolayer also melts.

The temperature range over which this frozen monolayer exists is about 10 times greater than what's observed at the liquid-vapor interfaces of similar materials. According to Alexei Tkachenko, a theoretical physicist who works at Brookhaven's Center for Functional Nanomaterials, "The temperature range of the surface-frozen layer and its temperature-dependent thickness can be described by a very simple model that we developed. What is remarkable is that the surface layer does not freeze abruptly as in the case of ice, or any other crystal. Rather, a smooth transition occurs over a temperature range of several degrees."

Said Ocko, "These films are better ordered and smoother than all other organic monolayer films created to date."

Moshe Deutsch added, "The results of this study and the theoretical framework which it provides may lead to new ideas on how to make defect-free, single molecule-thick films."

Funding for this work was provided by the U.S. Department of Energy's Office of Science and the U.S.-Israel Binational Science Foundation.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by DOE/Brookhaven National Laboratory.

Journal Reference:

B. Ocko, H. Hlaing, P. Jepsen, S. Kewalramani, A. Tkachenko, D. Pontoni, H. Reichert, M. Deutsch. Unifying Interfacial Self-Assembly and Surface Freezing. Physical Review Letters, 2011; 106 (13) DOI: 10.1103/PhysRevLett.106.137801

Hollywood Comes To ACS At #ACSAnaheim

Hollywood writers brought a touch of glamour to a standing-room-only symposium at the ACS national meeting yesterday. Writers for “Breaking Bad,” “Eureka,” “House M.D.” and other TV series admitted they found their audience of chemists intimidating but with self-deprecating good humor shared their philosophy for trying to make their shows scientifically sound.

“Breaking Bad” follows a high school chemistry teacher dying of lung cancer who cooks and sells crystal meth to support his family after his pending death. Moira Walley-Becket, one of the show’s seven writers, said that “getting the science right is of the utmost importance to us.” After all, she noted, “we need to know how to dissolve a body in acid.”

She said the writers turn for help to “the brilliant and tolerant” Donna J. Nelson, a chemistry professor at the University of Oklahoma, in Norman. Nelson volunteered for the gig after reading in C&EN that the show had to do its research on the Internet because it couldn’t afford a paid science adviser. Here’s a typical knotty problem: “Using the P2P method, how much meth could you synthesize with 30 gallons of methylamine?” (Answer: 223 lbs.)

Other scientists have found their way to Hollywood through the Science & Entertainment Exchange, a National Academy of Sciences program that connects entertainment industry professionals with scientists and engineers to help bring cutting-edge science to their stories.

Kevin R. Grazier, a research scientist at the Jet Propulsion Lab who clearly relishes his role as science adviser to “The Zula Patrol,” “Battlestar Galactica,” and other TV series, conceded that many scientists hesitate to work in Hollywood because it’s perceived as shallow. But as ACS President Nancy B. Jackson noted in her introduction to the symposium, there are many innovative ways of communicating with the public about science, including storytelling.