Thursday, July 14, 2011

Nano detector for deadly anthrax

An automatic and portable detector that takes just fifteen minutes to analyze a sample suspected of contamination with anthrax is being developed by US researchers. The technology amplifies any anthrax DNA present in the sample and can reveal the presence of just 40 microscopic cells of the deadly bacteria Bacillus anthracis.

B. anthracis, commonly known as anthrax, is a potentially lethal microbe that might be used intentionally to infect victims through contamination of food and water supplies, aerosolized particles, or even dried powders, such as those used in bioterrorist attacks in the USA. Detection is crucial to preventing widespread fatalities in the event of an . However, the complexity of the microbe's biology have so far made it difficult to build a portable system that can be employed quickly in the field. That said, there are several systems available that use PCR to amplify a particular component of the present in anthrax and then to flag this amplified signal. These systems are fast and sensitive but do not integrate sample preparation and so are not as convenient as a single detector unit would be.

Writing in the International Journal of Biomedical and Nanotechnology this month, Nathaniel Cady of the College of Nanoscale Science and Engineering (CNSE) of the University at Albany and colleagues there and at Cornell University, New York, explain how they have constructed nanofabricated fluidic cartridges that can be used to carry out detection of anthrax. The device is a so-called "lab-on-a-chips" device, or more properly a 3D microfluidic network that contains nanofabricated pillar structures.

The device has fluidic inputs for adding sample and reagents, removing waste, for carrying out DNA purification, and critically an integrated chamber for amplifying only the target DNA in the sample using the (PCR) system. The chip also contains a wave guide for the fluorescence-based identification of the amplified DNA and thus the target microbe. Importantly, the system works without manual intervention other than loading a droplet of sample into the detector.

"The average time required for DNA purification during these experiments was approximately 15 min, and when combined with real-time PCR analysis, this resulted in an average time to detection of 60 min," the team says. The system can detect as few as 40 B. anthracis cells. "Due to its small size and low power requirements, this system can be further developed as a truly portable, hand-held device," the researchers conclude.

More information: "PCR-based detection of Bacillus anthracis using an integrated microfluidic platform" in Int. J. Biomed. Nanosci. Nanotechnol., 2011, 2, 152-166

Provided by Inderscience Publishers (news : web)

Plastic cell membranes for faster and cheaper drug development

Synthetic cell membranes invented at the Institute of Materials Research and Engineering (IMRE), a research institute of Singapore’s Agency for Science, Technology and Research (A*STAR), may improve the way we identify and develop drugs by speeding up and reducing the cost of the drug screening process. The technology earned a spot as one of the twelve finalists in the Asian Innovation Awards 2011 organized by the Wall Street Journal Asia.

They may look and act like natural human cell membranes but the synthetic cell membranes invented by A*STAR’s IMRE have more advantages. IMRE’s patented synthetic cell membranes can be made-to-order, are easier to maintain in a laboratory environment and do not require the lengthy preparation that comes with working on live cell membranes. The synthetic cell membranes mimic the natural functions of cell membranes, such as interacting with drug molecules and antibodies, which is crucial in the drug discovery process. The innovation also provides a more stable membrane model for a better understanding of the mechanisms of diseases that affect human cells.

A team of researchers led by IMRE’s Dr. Madhavan Nallani successfully used synthetic materials to mimic biological processes. “We have harnessed natural cellular processes to fabricate a simple yet functional system using engineered materials to mimic the and its proteins,” said Dr. Nallani, the IMRE scientist who invented the synthetic cell membranes. “These artificial cell membranes allow researchers to study interactions between membrane proteins, drugs and other compounds without the hassle of using living materials.”

“Cells communicate with each other through membrane proteins. The disruption of this communication mechanism causes diseases like cancer, diabetes and even Parkinson’s disease. Understanding the workings of membrane proteins is very crucial in creating medicines to combat these diseases,” explained Professor Eva Sinner, a visiting scientist at IMRE who works on biomaterials and is involved in the project.

Current methods of drug testing require living cells, which entail high capital and maintenance costs, as well as specialists to operate sophisticated equipment. IMRE’s patented synthetic cell membranes, which are essentially inserted into a stable polymer matrix outside a cellular environment, creates a platform for researchers to work on that both simple to use and easy to maintain.

“This innovation is a classic example of how materials R&D can be applied to biomedical technologies,” said Prof Andy Hor, Executive Director of IMRE. “The success of this technology will be a great boost in helping create better drugs faster and more cost effectively.”

Dr. Nallani is currently looking for partners to commercialise the technology. The invention has direct impact and application in fields like drug discovery, antibody and therapeutics development, and drug delivery, which are collectively worth some US$170 billion dollars.

Provided by Agency for Science, Technology and Research (A*STAR)

Researchers closer to understanding cell-division gatekeeper enzyme

 An enzyme called Pin1 regulates the protein that initiates cell division by changing the shape of a peptide bond. Researchers at Notre Dame and Virginia Tech have discovered how Pin1 communicates through an internal conduit between its two domains to decide whether it will open or shut the gate to cell division.

The research is reported in the early online edition of the (PNAS) the week of July 4 in the article, "Stereospecific gating of functional motions in Pin1," by Andrew T. Namanja, Xiaodong J. Wang, Bailing Xu, Ana Y. Mercedes-Camacho, Kimberly A. Wilson, Felicia A. Etzkorn, and Jeffrey W. Peng.

"We are trying to understand the fundamental molecular workings of how Pin1 binds cis and trans shaped , and how binding each shape sets up a different dynamic communication link," said Etzkorn, professor of bioorganic chemistry in the College of Science at Virginia Tech.

It has been determined that Pin1 can bind (small ) in both domains at the same time, and that the two domains communicate across the protein. Peng, associate professor of biophysics at the University of Notre Dame, is looking at the dynamics of this communication.

"Where in the past people have taken photos – stopped action images – Jeff Peng is in effect shooting video, capturing the protein in action," said Etzkorn.

"What we discovered is that the dynamics of Pin1 change, depending whether its partner is cis or trans shaped. It moves stiffly when bound to cis and more loosely when bound to trans," said Peng.

The researchers previously used nuclear magnetic resonance (NMR) to measure the ligand dynamics of cis and trans bound to the protein (reported in the Journal of the American Chemical Society, April 1, 2010).

Etzkorn explains that cis binds solely to the catalytic domain (peptidyl-prolyl isomerase), and trans binds to both the catalytic and WW (Trp-Trp) domains. "The catalytic reaction is a shape shift, which swings the gate open or closed in effect," she said.

The catalytic domain and the WW domain are both parts of Pin1. What the PNAS article reports is how the protein communicates between the two domains, and how the dynamics of Pin1 affects that communication. "We showed that the quality of communication across the interface of the two domains is different depending upon whether cis or trans is bound." said Peng.

"What we are really trying to understand is what Pin1 is doing when it is bound to its native cis or trans substrate, why there are two domains, and how they work together, essentially how the works," said Etzkorn.

Understanding the workings of Pin1 has many applications. For example, if Pin1 can be shut down, then cell death occurs, which is a good thing if the dividing cell is a cancer cell. "Understanding the dynamics of ligand binding to Pin1 will help with rational drug design," said Etzkorn.

"Many proteins are modular and flexible, and thus may exploit the dynamic gating strategies we’ve found in Pin1," said Peng.

More information:

Provided by Virginia Polytechnic Institute and State University

A novel enzymatic catalyst for biodiesel production


Continuous production of biodiesel can now be envisaged thanks to a novel catalyst developed by a French team at CNRS's Centre de Recherches Paul Pascal (CRPP). The results, which have been patented, have just been published in the journal Energy & Environmental Science.

Biofuel production provides an alternative to fossil fuels. Biodiesels, for instance, are processed products based on oils from oleaginous plants such as oilseed rape, palm, sunflower and soybeans. They result from a chemical reaction, catalyzed in either an acidic or preferably a basic medium, between a vegetable oil (90%) and an alcohol (10%). This reaction, known as transesterification, converts the mixture into a methyl ester (the main constituent of biodiesel) and glycerol. A saponification side reaction (methyl ester conversion into the corresponding acid salt) reduces methyl ester yield. To increase the yield, it was therefore necessary to develop alternative catalysts.

For this type of reaction, certain enzymatic catalysts such as those belonging to the family of lipases (triglyceride hydrolases) are particularly efficient and selective. However, their high cost and low conformational stability restrict their industrial use, unless they can be irreversibly confined in porous matrices, allowing good accessibility and enhanced mass transport. This has now been achieved by the team led by Professor Renal Backov.

In an initial study, they had already demonstrated the possibility of efficient catalysis, by developing modified silica-based cellular matrices that make it possible to confine lipases in order to obtain exceptional yields for hydrolysis, esterification and transesterification reactions. Their work had also shown that unpurified enzymes could be used in the matrices. The fact that they were unpurified was a first step to significantly reducing the cost of biocatalysts. However, the methodology did not allow continuous production. This obstacle has now been overcome.

Researchers have developed a new method that generates the cellular hybrid biocatalyst in situ inside a chromotography column. This novel approach makes it possible to carry out continuous, unidirectional flow synthesis over long periods, since catalytic activity and ethyl ester production are maintained at high, practically steady levels during a two-month period of time. These results are amongst the best ever obtained in this field.

Research is continuing into solvent-free conversion of triesters, aimed at minimizing waste production and curbing the use of solvents and metals in chemical transformation processes. This work, which meets current energy and environmental requirements, shows how much chemists are working in the public interest, and confirms the importance of integrative chemistry.

More information: References:

-- “Enzyme-Based Biohybrid Foams Designed for Continuous Flow Heterogeneous Catalysis and Biodiesel Production”, N.Brun, A.Babeau-Garcia, M.-F.Achard, C.Sanchez, F.Durand, L.Guillaume, M.Birot, H.Deleuze and R.Backov - Energy & Environmental Science, 2011 DOI:10.1039/C1EE01295A

-- Catalyseur enzymatique hétérogene, procédé de préparation et utilisation pour la catalyse enzymatique en flux continu. N.Brun, H.Deleuze, C.Sanchez and R.Backov. French patent 2010. File number FR10-56099.

Provided by CNRS (news : web)