New synchrotron X-ray technique could see hidden building blocks of life

 

Scientists from Finland and France have developed a new synchrotron X-ray technique that may revolutionize the chemical analysis of rare materials like meteoric rock samples or fossils. The results have been published on 29 May 2011 in Nature Materials as an advance online publication.

Life, as we know it, is based on the chemistry of carbon and oxygen. The three-dimensional distribution of their abundance and chemical bonds has been difficult to study up to now in samples where these elements were embedded deep inside other materials. Examples are tiny inclusions of possible water or other chemicals inside martian rock samples, fossils buried inside a lava rock, or minerals and chemical compounds within meteorites.

X-ray tomography, which is widely used in medicine and material science, is sensitive to the shape and texture of a given sample but cannot reveal chemical states at the macroscopic scale. For instance graphite and diamond both consist of pure carbon, but they differ in the chemical bond between the carbon atoms. This is why their properties are so radically different. Imaging the variations in atomic bonding has been surprisingly difficult, and techniques for imaging of chemical bonds are highly desirable in many fields like engineering and research in physics, chemistry, biology, and geology.

 

Now an international team of scientists from the University of Helsinki, Finland, and the European Synchrotron Radiation Facility (ESRF), Grenoble, France, has developed a novel technique that is suitable exactly for this purpose. The researchers use extremely bright X-rays from a synchrotron light source to form images of the chemical bond distribution of different carbon forms embedded deep in an opaque material; an achievement previously thought to be impossible without destroying the sample.

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The left part of the image shows a photograph of the sample, measuring approximately 7 x 10 x 5mm3. The part studied with X-rays was the indicated subvolume of 7 x 2 x 1mm3. The result, a detailed 3D map of chemical bonds, is visualised here as a 2-D cut through the subvolume, shown on the right, where the different colors represent the different chemical carbon bonds present in the sample. Credit: Simo Huotari (Helsinki University). With permission by Nature Materials.

"Now I would love to try this on Martian or moon rocks. Our new technique can see not only which elements are present in any inclusions but also what kind of molecule or crystal they belong to. If the inclusion contains oxygen, we can tell whether the oxygen belongs to a water molecule. If it contains carbon, we can tell whether it is graphite, diamond-like, or some other carbon form. Just imagine finding tiny inclusions of water or diamond inside martian rock samples hidden deep inside the rock", says Simo Huotari from the University of Helsinki.

The newly developed method will give insights into the molecular level structure of many other interesting materials ranging, for example, from novel functional nanomaterials to fuel cells and new types of batteries.

More information: Simo Huotari et al., Direct tomography with chemical-bond contrast, Nature Materials advanded online publication, 29 May 2011, DOI:10.1038/NMAT3031

Provided by European Synchrotron Radiation Facility

Putting the 'fuel' in biofuels

Recent discussions of methods by which biomass -- grasses, trees, and other vegetation -- could be turned into fuel makes a lot of sense in theory. Plant matter is composed of energy-intensive carbohydrates, but even now scientists still don't have the perfect solution for converting plant sugars into combustible fuels.

"There's a real challenge in the catalysis and conversion process that we face, which is that nature and evolution have already fashioned far better catalysts than we could create on our own—namely enzymes," said materials scientist Christopher Marshall, who leads the Institute for Atom-Efficient Chemical Transformations (IACT) at the U.S. Department of Energy's (DOE) Argonne National Laboratory. "In order to aid the transition away from a petroleum-based economy, we have to take our cues from the catalysts that have existed for millions of years."

Using actual biological enzymes would not be a workable solution, since enzymes work too slowly to be effective. For the purposes of converting biomass to biofuels, researchers need to synthesize biologically-inspired inorganic catalysts that balance the need for molecular specificity and high reaction rates.

"When it comes to catalyst discovery, everything's based around a particular set of trade-offs," Marshall said.

Potential catalysts for biofuel production have traditionally come from the precious metals and their elemental cousins. According to Marshall, scientists have found an increasing spectrum of applications first for platinum, and then for a platinum-molybdenum hybrid. "Slightly different chemistries can produce dramatically different results both in terms of efficiencies and specificities," he said. "We're really just trying to fashion the best molecular jigsaw pieces we can to fit this larger puzzle."

IACT was founded in 2009 as part of the DOE's effort to establish a set of several dozen Energy Frontier Research Centers (EFRCs) around the country that would contain five-year interdisciplinary programs focused around discrete scientific challenges. As part of the overall effort to transform the energy economy, Argonne also leads research into improved lithium-ion battery technology and new photovoltaic devices that can better capture solar energy.

Converting biomass to biofuels requires the use of a great deal of hydrogen, an element that Marshall said can be hard to manufacture. "The current methods of getting the hydrogen we need to do the conversion require the input of just as much energy as we'd get out of the fuels we'd be trying to create," he said. "In order to really get biofuels to take off, we first have to tackle the problem of where we're going to get all the hydrogen we need."

Because hydrogen is contained within the carbohydrate backbone of plant matter, ideally scientists hope to find a self-sustaining process in which the hydrogen needed for the conversion of biomass to biofuels can be extracted from the biomass itself. To do so requires the development of robust inorganic materials based on nanotechnology that can improve the multistep process of going from woodchipper to gas tank.

Researchers who collaborate in the IACT come from a variety of different technical backgrounds, including materials design, synthesis and characterization, theoretical chemistry and computational studies. "By combining all of these approaches, we hope to gain an understanding of how these key reactions work and how we can optimize the effectiveness of these catalysts both in terms of their selectivity and their rate of reaction. We want to use these catalysts as scalpels, not chainsaws," Marshall said.

Provided by Argonne National Laboratory (news : web)

Cystic fibrosis bacteria could help fight back against antibiotic resistance

A bacteria which infects people with cystic fibrosis could help combat other antibiotic-resistant microbes, according to a team from Cardiff and Warwick Universities.

Continuous use of existing antibiotics means that resistant bacteria are now causing major health problems all over the world. New antibiotics are urgently needed to combat the emergence of multidrug-resistant bacteria such as the MRSA superbug.

Now a surprising source of hope has emerged in the form of Burkholderia, a group of bacteria which can cause severe lung infections in people with the genetic disorder cystic fibrosis. However, the Cardiff and Warwick team has now discovered antibiotics from Burkholderia are effective against MRSA and even other cystic fibrosis infecting bacteria.

Dr Eshwar Mahenthiralingam, of Cardiff University's School of Biosciences, Cardiff University, has been studying Burkholderia for the last decade. Using forensic fingerprinting tests to genetically identify the bacteria, Dr Mahenthiralingam's research group has tracked strains all over the world and helped develop guidelines to prevent it spreading.

By the summer of 2007, Dr Mahenthiralingam had built up a large collection of Burkholderia bacteria. He and his team then decided to screen them for antibiotics active against other bacteria, particularly drugs with the potential to kill other bacteria that infect cystic fibrosis patients. Over the next two years, Dr Mahenthiralingam's team discovered that around one quarter of Burkholderia bacteria have very strong antibiotic activity on multidrug-resistant pathogens such as MRSA. One particular strain, Burkholderia ambifaria, was found to produce two very potent antibiotics active on resistant bacteria, in particular Acinetobacter baumanii.

The chemical structures of the antibiotics, called enacyloxins, were determined by Professor Gregory Challis and Dr. Lijiang Song at the University of Warwick, demonstrating that they belong to one of the most successful families of natural product drugs, the polyketides. Other examples of polyketides include erythromycin, which is used to cure many bacterial infections, and doxorubin, used as an anti-cancer drug. Professor Challis commented: "The combination of enzymes used by Burkholderia to make the enacyloxins is very unusual. Our insights into this process should allow us to use cutting edge synthetic biology techniques to produce novel enacyloxin analogues with improved pharmaceutical properties."

The team's findings have now been published in the journal Chemistry and Biology. Dr Mahenthiralingam commented: "Burkholderia are soil bacteria like Streptomyces, which are the source of most of our current antibiotics. Our research therefore offers real hope of a completely new source for the identification and engineering of highly potent antibiotics. With antibiotic resistant bacteria causing great suffering around the world, these new sources are urgently needed."

The chemical structures of the antibiotics, called enacyloxins, were determined by Professor Gregory Challis and Dr. Lijiang Song at the University of Warwick, demonstrating that they belong to one of the most successful families of natural product drugs, the polyketides. Other examples of polyketides include erythromycin, which is used to cure many bacterial infections, and doxorubin, used as an anti-cancer drug. Professor Challis commented: "The combination of enzymes used by Burkholderia to make the enacyloxins is very unusual. Our insights into this process should allow us to use cutting edge synthetic biology techniques to produce novel enacyloxin analogues with improved pharmaceutical properties."

Provided by Cardiff University (news : web)