Wednesday, February 15, 2012

Capsules that clean: New-look laundry detergents head for supermarket shelves

C&EN Assistant Managing Editor Michael McCoy explains that the technology behind films used to package the single doses of detergent have come a long way in the five decades since their debut. Previous versions of the encapsulating films interacted poorly with the detergent and had short shelf-lives. And another type of single-dose formulation — essentially a tablet of compressed laundry powders — didn't dissolve fully, leaving partially consumed chunks among the clean clothes.

In recent years, single-dose liquids packaged in polyvinyl alcohol film have caught on in the U.K. and France. The German company Henkel now has plans to market a similar "mono-dose" in the U.S. in the coming weeks, and Procter & Gamble plan to launch "Tide Pods" within a month. The same dose is used regardless of the amount of that needs to be washed. Although the main technical challenges have been solved, experts say that "the jury is still out" on whether are ready for these products.

More information: Selling Detergents One Load At A Time -

Provided by American Chemical Society (news : web)

Light but stable: novel cellulose-silica gel composite aerogels

Gels are familiar to us in forms like Jell-O or hair . A gel is a loose molecular network that holds liquids within its cavities. Unlike a sponge, it is not possible to squeeze the liquid out of a gel. An aerogel is a gel that holds air instead of a liquid. For example, aerogels made from silicon dioxide may consist of 99.98 % air-filled pores. This type of material is nearly as light as air and is translucent like solidified smoke. In addition, it is not flammable and is a very good insulator—even at high temperatures. One prominent application for aerogels was the insulation used on space shuttles. Because of their extremely high inner surface area, aerogels are also potential supports for catalysts or pharmaceuticals. Silica-based aerogels are also nontoxic and environmentally friendly.

One drawback, however, has limited the broader application of these airy materials: silica-based aerogels are very fragile, and thus require some reinforcement. In addition to reinforcement with synthetic polymers, biocompatible materials like are also under consideration.

The researchers at Wuhan University (China) and the University of Tokyo (Japan) have now developed a special composite aerogel from cellulose and silicon dioxide. They begin by producing a cellulose gel from an alkaline urea solution. This causes the cellulose to dissolve, and to regenerate to form a nanofibrillar gel. The cellulose gel then acts as a scaffold for the silica gel prepared by a standard sol–gel process, in which a dissolved organosilicate precursor is cross-linked, gelled, and deposited onto the cellulose nanofibers. The resulting liquid-containing composite gel is then dried with supercritical carbon dioxide to make an aerogel.

The novel aerogel demonstrates an interesting combination of advantageous properties: mechanical stability, flexibility, very low thermal conductivity, semitransparency, and biocompatibility. If required, the cellulose part can be removed through combustion, leaving behind a aerogel. The researchers are optimistic: "Our new method could be a starting point for the synthesis of many new porous materials with superior properties, because it is simple and the properties of the resulting aerogels can be varied widely."

More information: Jie Cai, Cellulose–Silica Nanocomposite Aerogels by In Situ Formation of Silica in Cellulose Gel, Angewandte Chemie International Edition, … ie.201105730

Provided by Wiley (news : web)

Protein study gives fresh impetus in fight against superbugs

Researchers have mapped the complex of an enzyme found in many bacteria. These – known as restriction enzymes – control the speed at which bacteria can acquire resistance to drugs and eventually become superbugs.

The study, carried out by an international team including from the University of Edinburgh, focused on E. coli, but the results would apply to many other infectious bacteria.

After prolonged treatment with , bacteria may evolve to become resistant to many drugs, as is the case with superbugs such as MRSA.

Bacteria become resistant by absorbing DNA – usually from other bugs or viruses – which contains genetic information enabling the bacteria to block the action of drugs. can slow or halt this absorption process. Enzymes that work in this way are believed to have evolved as a defence mechanism for bacteria.

The researchers also studied the enzyme in action by reacting it with DNA from another organism. They were able to model the mechanism by which the enzyme disables the foreign DNA, while safeguarding the bacteria's own genetic material. Restriction enzymes' ability to sever genetic material is widely applied by scientists to cut and paste strands of DNA in genetic engineering.

The study was carried out in collaboration with the Universities of Leeds and Portsmouth with partners in Poland and France. It was supported by the Biotechnology and Biological Sciences Research Council and the Wellcome Trust and published in Genes and Development journal.

Dr David Dryden, of the University of Edinburgh's School of Chemistry, who led the study, said: "We have known for some time that these enzymes are very effective in protecting from attack by other species. Now we have painted a picture of how this occurs, which should prove to be a valuable insight in tackling the spread of antibiotic-resistant superbugs."

Provided by University of Edinburgh

Researchers discover method to unravel malaria's genetic secrets

"The malarial has been a black box. Our technique allows us to open that box, so that we can learn what genes in the most lethal actually do," said Dennis Voelker, PhD, Professor of Medicine at National Jewish Health and senior author on the paper that appeared in the January 2, 2012 , issue of the . "This could prove tremendously valuable in the fight against a disease that has become increasingly drug-resistant."

The genome of P. falciparum was sequenced in 2002, but the actual functions of many of the organism's genes have remained elusive. One of the primary methods for discovering gene function is to copy a specific gene, insert it into a that is easy to grow, often the yeast Saccharomyces cerevisiae, then draw on the incredible knowledge base about yeast and its abundant genetic variants to discover how that inserted gene changes the organism's biology.

DNA is composed of building blocks with the shorthand designations A,T,C and G. The genome of P. falciparum is odd because it is particularly rich in A's and T's. Because of this A-T-rich nature, P. falciparum genes generally do not function when they are inserted into other organisms. As a result, scientists have been largely stymied when trying to understand the functions of P. falciparum's genes.

It turns out, however, that P. falciparum has a close cousin, P. knowlesi, which shares almost all its genes with P. falciparum, but with fewer A's and T's. As a result, P. knowlesi genes function well when inserted into yeast. Scientists can now insert P. knowlesi genes into yeast, discover their function, and then match them to corresponding genes in P. falciparum, which reveals the function of the malarial parasite's genes.

"This technique could lead to an explosion in knowledge about malaria and the parasite that causes it." said Dr. Voelker.

The researchers used the technique to discover a new gene involved in the synthesis of lipids in cell membranes of P. falciparum. The gene, phosphatidylserine decarboxylase, directs the formation of a protein unique to malarial parasites and is a potential therapeutic target. For example, selective disruption of in P. falciparum, would prevent the organism from making new cell membranes, growing and reproducing in human hosts.

Provided by National Jewish Health

Researchers seek to beat 'molecular obesity'

Professor Andrew Hopkins and his team from the University's College of have developed a that they believe has the potential to more effectively identify compounds that have the best chance of being successfully developed into drugs to treat and protect against disease.

In order to succeed as a drug, a compound has to have the right balance of properties. Those compounds that are too large or too greasy - said to be molecularly obese - tend not to be well absorbed by the body when taken orally as pills and have been blamed for increasing rates of failure and rising costs in the drug development process.

This is why the most commonly used and effective orally dosed drugs that are available on the market tend to be relatively small and lean. Compounds sharing these properties are said to be "drug-like" and assessment of "drug-likeness" is a key consideration when selecting compounds for further development.

Until now this assessment has been made according to a widely used set of rules that determine whether or not compounds are suitable for further development as orally absorbed pills.

However, the evaluation of drug-likeness in black and white terms does not adequately reflect the whole spectrum of compound quality as many successful drugs apparently 'break the rules' so the Dundee team set about developing an alternative model.

They have pioneered a measure of drug-likeness based on the concept of desirability called Quantitative Estimate of Druglikeness (QED) which rates a compound between 0-1 based on its molecular properties, with 1 indicating an ideal candidate.

Once the scores have been calculated any set of compounds can be easily ranked by their relative merit. Importantly, the formula is derived entirely from historical data on the observed properties of successful drugs. This approach is more flexible than simply attributing a pass or fail to a compound, and offers several advantages to researchers looking to develop new drugs, according to Professor Hopkins.

"We think this may be a better way of appraising compounds in drug discovery," he said. "What we are trying to overcome is a problem of judging which compounds have the lowest risk of failure before synthesizing or buying them. This is important because the cost of drugs is in part driven by the high failure rate in developing new therapies.

"Compounds that don't have the correct properties or features make them particularly unsuitable, but this doesn't tell the whole story. Scientists judge them according to the rules, which might suggest a particular compound will work, but not that they will only work to a certain extent and that there are more effective alternatives available.

"Over the past two decades the compounds made by the pharmaceutical industry have tended to get larger and greasier. This trend has been called molecular obesity, and while these "obese" compounds may pass the rules they are far from the ideal.

"Some experts in the industry argue that the increasing failure rate and increasing cost in developing new drugs may be due to the rise in molecular obesity of new compounds. QED gives us a new tool to guide drug design toward leaner, fitter, more attractive compounds, with hopefully a greater overall chance of success.

"The rules which chemists use are useful, but only as far as telling us that it does or doesn't work. We are trying to get away from the concept of using hard and fast rules and looking instead at the shades of grey, which reflect the reality of the situation. What we are trying to do is increase the odds of identifying a successful compound."

The Dundee team's work is published in the most recent edition of the Nature Chemistry journal. The paper, entitled 'Quantifying the chemical beauty of drugs', is co-authored by colleagues in England and Sweden.

After attributing values to several thousand compounds, the researchers asked around 80 chemists to evaluate them based on their own knowledge and scientific methods. This showed that the Dundee method was an effective way of identifying attractive candidates which agreed very well with the chemists' intuition.

Professor Hopkins continued, "Chemists often refer to compounds as looking "good, bad or ugly" according to their suitability, and we asked the chemists who took part in this survey whether a drug was attractive or not, and found their tacit knowledge fitted well with our calculation.

"The whole idea is to use statistics, data, and underlying probability distributions which has been gathered on drugs over the years to help us more quickly and effectively identify attractive compounds in the future.

"The formula encodes the properties that seem to determine a compound's attractiveness, and reflects the knowledge required in discovery. What we found exciting is the idea of a mathematical formula that reflects the chemists experience and intuition of what they consider an "attractive" compound to synthesise.

"From here we can develop a more nuanced approach to identifying lower risk for ."

Provided by University of Dundee