Wednesday, April 13, 2011

Battery-less chemical detector developed

Unlike many conventional chemical detectors that require an external power source, Lawrence Livermore researchers have developed a nanosensor that relies on semiconductor nanowires, rather than traditional batteries.

The device overcomes the power requirement of traditional sensors and is simple, highly sensitive and can detect various molecules quickly. Its development could be the first step in making an easily deployable chemical sensor for the battlefield.

The Lab's Yinmin "Morris" Wang and colleagues Daniel Aberg, Paul Erhart, Nipun Misra, Aleksandr Noy and Alex Hamza, along with collaborators from the University of Shanghai for Science and Technology, have fabricated the first-generation battery-less detectors that use one-dimensional semiconductor nanowires.

The nanosensors take advantage of a unique interaction between chemical species and semiconductor nanowire surfaces that stimulate an electrical charge between the two ends of nanowires or between the exposed and unexposed nanowires.

The group tested the battery-less sensors with different types of platforms -- zinc-oxide and silicon -- using ethanol solvent as a testing agent.

In the zinc-oxide sensor the team found there was a change in the electric voltage between the two ends of nanowires when a small amount of ethanol was placed on the detector.

"The rise of the electric signal is almost instantaneous and decays slowly as the ethanol evaporates," Wang said.

However, when the team placed a small amount of a hexane solvent on the device, little electric voltage was seen, "indicating that the nanosensor selectively responds to different types of solvent molecules," Wang said.

The team used more than 15 different types of organic solvents and saw different voltages for each solvent. "This trait makes it possible for our nanosensors to detect different types of chemical species and their concentration levels," Wang said.

The response to different solvents was somewhat similar when the team tested the silicon nanosensors. However, the voltage decay as the solvent evaporated was drastically different from the zinc-oxide sensors. "The results indicate that it is possible to extend the battery-less sensing platform to randomly aligned semiconductor nanowire systems," Wang said.

The team's next step is to test the sensors with more complex molecules such as those from explosives and biological systems.

The research appears on the inside front cover of the Jan. 4 issue of Advanced Materials.

Story Source:

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

Journal Reference:

Xianying Wang, Yinmin Wang, Daniel Aberg, Paul Erhart, Nipun Misra, Aleksandr Noy, Alex V. Hamza, Junhe Yang. Batteryless Chemical Detection with Semiconductor Nanowires. Advanced Materials, 2011; 23 (1): 117 DOI: 10.1002/adma.201003221

Center to revolutionize chemical manufacture is open for business

An EPSRC (Engineering and Physical Sciences Research Council) Centre for revolutionising the way pharmaceuticals and other chemicals are made is being officially launched April 8.

The collaborative initiative involving leading academics and industrialists, led by the University of Strathclyde in Glasgow, is seeking quicker, more effective and more sustainable methods of manufacturing products such as medicines, foodstuffs, dyes, pigments and nanomaterials.

The research team plans to develop a better understanding of the way these products form and to improve ways to control this, using new processes for manufacturing. The chemical and pharmaceutical sectors are worth L113 billion to the UK economy annually in sales and the new national EPSRC centre will improve and accelerate the production of a broad range of products.

In particular, by delivering better control over the process of crystallisation, the research team will create new opportunities for innovation in solid chemical products such as pharmaceuticals.

The new Centre will allow leading research teams to work together to develop technologies that ensure medicines and other materials can be produced using continuous manufacturing approaches, rather than using traditional batch methods. A key aspect to this is developing crystallisation technologies that deliver better control than is currently possible. In addition to the more efficient use of materials and resources, these techniques offer the opportunity to reduce running costs by up to 60% and energy requirements by up to 70%.

Strathclyde is leading the EPSRC Centre for Innovative Manufacturing in Continuous Manufacturing and Crystallisation, which also involves the Universities of Bath, Cambridge, Edinburgh, Glasgow, Heriot-Watt and Loughborough. Substantial support is also being provided by industry partners that include GlaxoSmithKline, Pfizer, AstraZeneca, Fujifilm, British Salt, Croda International plc, Genzyme Ltd, NiTech Solutions, Phoenix Chemicals and Solid Form Solutions Ltd.

Professor Alastair Florence, of the Strathclyde Institute of Pharmacy and Biomedical Sciences, is Director of the new Centre. He said: "We are delighted to be establishing this new EPSRC Centre that brings together leading academic expertise in crystallisation, analysis, chemistry, formulation and manufacturing from across the UK.

"This unique national Centre will provide a focus for early stage engineering and physical sciences research that will ultimately feed through directly to the activities of Technology and Innovation Centres and industry, making a radical and much-needed impact on the production of many different high-value products. By working together in this way, the UK research community will contribute to the competitiveness of companies across a variety of important sectors including pharmaceuticals, fine chemicals, dyes & pigments, energy, food and drink.

"We will carry out an innovative programme of research and, by close engagement with our industrial colleagues, ensure that the exciting new research programme is targeted to areas of real national need. In this way, for example, the research carried out with the support of this award will benefit patients through better medicines, produced more efficiently, at lower cost and more sustainably.

"In addition to improving the way drug substances are produced, work within the Centre will also explore alternative approaches to manufacturing the medicines in which drugs are delivered to patients. This could include alternatives to the traditional tablet that are also safe and effective but are more straightforward to make. Whilst we have a significant focus around pharmaceuticals, we have many different chemical sectors involved in the Centre, which will ensure the broad exploitation of the research outcomes across the chemical process industries."

The Centre is part of a L51 million investment by EPSRC in nine new centres officially launched April 8, through the UK-wide EPSRC Centre for Innovative Manufacturing programme. It has received a grant of L4.9 million from the programme and support worth a total of L1.8 million is also being contributed by industry, with a further L1 million coming from the universities to establish a new partnership between universities, industry and the public sector in this area.

It follows the launch of the L89 million Technology and Innovation Centre (TIC) at Strathclyde, a world-leading centre for transforming the way universities, business and industry collaborate to bring global competitive advantage to Scotland. The TIC and the new EPSRC centre will work in parallel, forging greater collaboration between academic researchers and industry.

The Centre for Innovative Manufacturing team of researchers, from seven leading UK universities and a range of industrial partners, harnesses skills and expertise in chemistry, chemical engineering, crystallisation, pharmaceutical sciences, manufacturing and operations management.

The group will:

Establish a World Class Research Centre to improve manufacturing performance in the UK process industriesStimulate innovation and commercialisation of new technologies, particularly through SMEs and startup companiesEngage with global companies across a range of sectorsDevelop international research and development networks

The EPSRC Centre will also play an important role in training the scientists of the future in an international centre of excellence.

The partners in the EPSRC Centre for Innovative Manufacturing project plan to secure further funding from a range of sources to grow the Centre and extend its activity beyond the initial five-year funding period. This builds on other recent success in this area for the collaborating universities- a grant from the Scottish Funding Council Horizon fund (SPIRIT), made in 2010, established an initial cohort of nine PhD students, three at Strathclyde.

Strathclyde has also invested a further L500,000 in a new multidisciplinary continuous processing lab, due to open this summer, and will bring together existing teams at the University and house a suite of state-of-the-art reactor devices for continuous manufacturing and crystallisation.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Strathclyde, via EurekAlert!, a service of AAAS.

Are we only a hop, skip and jump away from controlled molecular motion?

ScienceDaily (Apr. 10, 2011) — Scientists may very well be a hop, skip and jump away from controlled molecular motion, according to a study in this month's Nature Chemistry.

Controlling how molecules move on surfaces could be the key to more potent drugs that block the attachment of viruses to cells, and will also speed development of new materials for electronics and energy applications. The study is the culmination of a EU-funded collaboration between Tyndall National Institute, UCC researcher Dr. Damien Thompson and colleagues at University of Twente in the Netherlands. Dr. Thompson performed computer simulations that enabled a greater understanding of how two-legged molecules move along patterned surfaces, in a kind of molecular hopscotch.

Widespread industrial uptake of nanotechnology requires cheap, easy and robust solutions that allow manipulation of matter at the smallest scales and so a key enabling feature will be the ability to move material around molecule by molecule. One of the major difficulties is the very different physics that operates at the scale of atoms and molecules; water, for example, feels more like treacle to a molecule, and molecules tend to huddle and stick together due to microscopic forces between their atoms. Dr. Thompson explains: "The experiments performed by the group at Twente were very elegant. They involved making two-legged molecules and using a fluorescence microscope to watch how they move along a wet surface. The molecules are hydrophobic, meaning they don't like water, and the surface was pockmarked with hydrophobic cavities so a weak glueing interaction, based on a mutual dislike of water, drives the interaction between the molecules and the surface.

While the energetics of this type of interaction was worked out over a decade ago by George Whitesides's group at Harvard, it's usefulness for materials development was limited because little was known until now on the paths that the molecules take."

Because the molecules have multiple legs, they display a surprisingly rich behaviour at the surface, beyond simply attaching/detaching, with Dr. Thompson's computer simulations complementing the experiments and showing the different mechanisms by which the molecules move. The motion switches from walking to hopping to flying, as the environment changes.

Dr. Thompson continues: "Access to high performance computing facilities enabled us to model the different pathways and aid interpretation of the microscopy results. We ran most of the simulations on our own Science Foundation Ireland-supported computing clusters at Tyndall, and also did a few larger-scale calculations at the Irish Center for High End Computing. It's an exciting time for research as experiments and simulations are finally on the same page; the experiments can finally drill down far enough to see molecule-scale features while advances in computing mean we can routinely model systems composed of hundreds of thousands, and even millions, of atoms."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Tyndall National Institute, via AlphaGalileo.

Journal Reference:

AndrĂ¡s Perl, Alberto Gomez-Casado, Damien Thompson, Henk H. Dam, Pascal Jonkheijm, David N. Reinhoudt, Jurriaan Huskens. Gradient-driven motion of multivalent ligand molecules along a surface functionalized with multiple receptors. Nature Chemistry, 2011; 3 (4): 317 DOI: 10.1038/nchem.1005

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

'Green energy' advance: Tandem catalysis in nanocrystal interfaces

In a development that holds intriguing possibilities for the future of industrial catalysis, as well as for such promising clean green energy technologies as artificial photosynthesis, researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have created bilayered nanocrystals of a metal-metal oxide that are the first to feature multiple catalytic sites on nanocrystal interfaces. These multiple catalytic sites allow for multiple, sequential catalytic reactions to be carried out selectively and in tandem.

"The demonstration of rationally designed and assembled nanocrystal bilayers with multiple built-in metal-metal oxide interfaces for tandem catalysis represents a powerful new approach towards designing high-performance, multifunctional nanostructured catalysts for multiple-step chemical reactions," says the leader of this research Peidong Yang, a chemist who holds joint appointments with Berkeley Lab's Materials Sciences Division, and the University of California Berkeley's Chemistry Department and Department of Materials Science and Engineering.

Yang is the corresponding author of a paper describing this research that appears in the journal Nature Chemistry. Co-authoring the paper were Yusuke Yamada, Chia-Kuang Tsung, Wenyu Huang, Ziyang Huo, Susan Habas, Tetsuro Soejima, Cesar Aliaga and leading authority on catalysis Gabor Somorjai.

Catalysts -- substances that speed up the rates of chemical reactions without themselves being chemically changed -- are used to initiate virtually every industrial manufacturing process that involves chemistry. Metal catalysts have been the traditional workhorses, but in recent years, with the advent of nano-sized catalysts, metal,oxide and their interface have surged in importance.

"High-performance metal-oxide nanocatalysts are central to the development of new-generation energy conversion and storage technologies," Yang says. "However, to significantly improve our capability of designing better catalysts, new concepts for the rational design and assembly of metal-metal oxide interfaces are needed."

Studies in recent years have shown that for nanocrystals, the size and shape -- specifically surface faceting with well-defined atomic arrangements -- can have an enormous impact on catalytic properties. This makes it easier to optimize nanocrystal catalysts for activity and selectivity than bulk-sized catalysts. Shape- and size-controlled metal oxide nanocrystal catalysts have shown particular promise.

"It is well-known that catalysis can be modulated by using different metal oxide supports, or metal oxide supports with different crystal surfaces," Yang says. "Precise selection and control of metal-metal oxide interfaces in nanocrystals should therefore yield better activity and selectivity for a desired reaction."

To determine whether the integration of two types of metal oxide interfaces on the surface of a single active metal nanocrystal could yield a novel tandem catalyst for multistep reactions, Yang and his coauthors used the Lamgnuir-Blodgett assembly technique to deposit nanocube monolayers of platinum and cerium oxide on a silica (silicon dioxide) substrate. The nanocube layers were each less than 10 nanometers thick and stacked one on top of the other to create two distinct metal-metal oxide interfaces -- platinum-silica and cerium oxide-platinum. These two interfaces were then used to catalyze two separate and sequential reactions. First, the cerium oxide-platinum interface catalyzed methanol to produce carbon monoxide and hydrogen. These products then underwent ethylene hydroformylation through a reaction catalyzed by the platinum-silica interface. The final result of this tandem catalysis was propanal.

"The cubic shape of the nanocrystal layers is ideal for assembling metal-metal oxide interfaces with large contact areas," Yang says. "Integrating binary nanocrystals to form highly ordered superlattices is a new and highly effective way to form multiple interfaces with new functionalities."

Yang says that the concept of tandem catalysis through multiple interface design that he and his co-authors have developed should be especially valuable for applications in which multiple sequential reactions are required to produce chemicals in a highly active and selective manner. A prime example is artificial photosynthesis, the effort to capture energy from the sun and transform it into electricity or chemical fuels. To this end, Yang leads the Berkeley component of the Joint Center for Artificial Photosynthesis, a new Energy Innovation Hub created by the U.S. Department of Energy that partners Berkeley Lab with the California Institute of Technology (Caltech).

"Artificial photosynthesis typically involves multiple chemical reactions in a sequential manner, including, for example, water reduction and oxidation, and carbon dioxide reduction," says Yang. "Our tandem catalysis approach should also be relevant to photoelectrochemical reactions, such as solar water splitting, again where sequential, multiple reaction steps are necessary. For this, however, we will need to explore new metal oxide or other semiconductor supports, such as titanium dioxide, in our catalyst design."

This research was supported by the DOE Office of Science.

Story Source:

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

Journal Reference:

Yusuke Yamada, Chia-Kuang Tsung, Wenyu Huang, Ziyang Huo, Susan E. Habas, Tetsuro Soejima, Cesar E Aliaga, Gabor A. Somorjai, Peidong Yang. Nanocrystal bilayer for tandem catalysis. Nature Chemistry, 2011; DOI: 10.1038/nchem.1018

Genentech Says Experimental Cancer Combo is Safe

Genentech this week unveiled promising results from a Phase I study suggesting it is possible to safely combine two cancer drug candidates, its MEK inhibitor GDC0973 and its PI3K inhibitor GDC0941. In addition to a relatively clean safety profile, there were also early signs that the combination is combating cancer.

Genentech is one of several companies running a trial to test the safety of combining inhibitors of the lipid kinase PI3K, part of the PI3K/AKT/mTor pathway, and drugs blocking the protein kinase MEK, part of the KRas/MAP signalling pathway. As we discuss in our upcoming April 11th cover story on PI3K inhibitors, the rationale for knocking down both pathways  is compelling: both are considered to be crucial in cancer cells’ survival, and blocking only one pathway has more often than not proven ineffective.

As Robert Abraham, CSO of Pfizer’s oncology research unit, explains in Monday’s story:

“KRas mutations are associated with many of the deadliest cancers,” including colorectal and pancreatic, Pfizer’s Abraham says. Yet they are incredibly resistant to conventional chemotherapy, and based on preclinical studies of the mutations, are expected to be resistant to the new batch of mTor/PI3K inhibitors as well, he adds. The working hypothesis is that knocking out two of the major drivers of cancer—the KRas and PI3K pathways—could have a significant effect on the most recalcitrant tumors.

To date, there are at least six Phase I trials planned or ongoing that combine MEK inhibitors with compounds that block some aspect of the mTor/PI3K pathway. Merck and AstraZeneca made headlines in 2009 when they said they would partner to test Merck’s AKT inhibitor with AstraZeneca’s MEK inhibitor. Sanofi-Aventis has meanwhile teamed with Merck Serono to explore the potential of combining two of its PI3K inhibitors in combination with Merck Serono’s MEK inhibitor. GlaxoSmithKline has two of its own drugs in a combination trial, and its MEK inhibitor GSK1120212 is also being tested in combination with Novartis’ PI3K inhibitor BKM120. And while Pfizer has yet to initiate such a study, Abraham said the company is “keeping two eyes on that combination.”



Bummer SNP doesn’t mix with beer for gastric cancer risk


A study from led by investigators at the Catalan Institute of Oncology (ICO) in Barcelona has revealed that high consumption of beer combined with a single nucleotide polymorphism (SNP) in the alcohol dehydrogenase gene is associated with a nearly nine-fold increased risk of gastric cancer.

Thanks to the lovely folks in the American Association for Cancer Research (AACR) press office who recognize science bloggers as press, I was able to sit in on a press conference this morning at the AACR annual meeting in Orlando where several studies were discussed on genetic and environmental factors in cancer risk.

Lead author of this particular study, cancer epidemiologist Eric Duell, Ph.D., presented a study of Europeans on alcohol consumption and risk of gastric cancer due to SNPs in the alcohol dehydrogenase gene, ADH1. Recall from biochemistry that ADH1 and other ADH forms catalyze the rate-limiting step in the ethyl alcohol oxidation to acetaldehyde, a known carcinogen. Acetaldehyde, in turn, is oxidized to acetate by aldehyde dehydrogenases (ALDHs).

This is an impressive retrospective analysis. The study data was culled the European Prospective Investigation into Cancer and Nutrition (EPIC), a study of 521,000 individuals aged 35 to 50 who completed diet and alcohol use questionnaires at 23 centers across 10 European countries between 1992 and 1998. A subset, or nested-study, called EurGast examined environmental factors and genetic susceptibility to gastric cancer in 364 cases relative to 1272 controls.

When examined as a pool only one SNP was associated with a modest, 30% increased risk for gastric cancer.  Combining this SNP with alcohol consumption data revealed that 60 g EtOH/day increased risk by 75%. (Sixty grams of ethanol per day is the amount present in approximately four 12 oz beers at 5% alcohol by volume, four 5 oz glasses of wine at 12% ABV, or four 1oz shots of 100 proof liquor.)

However, the subanalysis of that SNP stratified for alcohol consumption and type of alcohol revealed the big surprise. Consumption as beer, but not wine or liquor, combined with this SNP at both alleles was associated with increased gastric cancer risk of 8.72-fold in this high consumption group (just one allele increased risk by only 33%). This SNP in the ADH1 gene, rs1230025, is an intergenic T›A polymorphism, neither in the promoter or the coding region of the gene.

The influence of this SNP has only been evaluated in one study where it was shown to be associated with a lower breath alcohol concentration – and presumably higher acetaldehyde concentration, although not explicitly measured – at late timepoints when normal volunteers are given a challenge of 0.75 g/kg of ethanol.

But why is beer the only alcoholic beverage with this increased gastric cancer risk in the background of this particular SNP? Alcohol is alcohol, right? I asked Duell about this point because he said that beer has low levels of nitrosamines, the liver and stomach procarcinogens. However, nitrosamines are not activated to their proximal carcinogenic species by ADHs but rather by the cytochrome P450 CYP2E1 (incidentally, the same CYP that oxidizes ethyl alcohol at high concentrations. Duell also noted that the levels of nitrosamines are much lower in beer today than earlier in the lifetime of the participants.

Instead, Duell said he was interested in “what [were] they eating when they were drinking beer.” I find this aspect fascinating but can’t quite figure what other dietary carcinogen people would be eating that was influenced by this particular ADH genotype. I’m also interested to know the carcinogenic potential of other alcohols metabolized by ADH that may be present in beer but not wine or liquor. All sorts of lovely organics are made by yeast depending on the strain used, the specific grains, pH, oxygenation, and other metabolic substrates.

Since subjects evaluated in this work spanned 10 countries, incoming AACR president Judy Garber, MD, asked Duell if the cases could be analyzed by nationality. Unfortunately, Duell said, the study would lose the power necessary to see differences in these smaller subgroups.

So what do these data mean to alcohol consumers?  Well, first, drinking ethyl alcohol at 60g or greater per day has many other health risks besides gastric cancer, regardless of which ADH SNPs one might have. (Indeed, there may have been some conference attendees who I saw last night drinking with this degree of enthusiasm.).

However, this particular SNP is really, really bad news. I’m hard-pressed to think of any environmental factor besides smoking that causes a nine-fold increase in risk of any cancer. I’d definitely suggest to the consumer genomics company 23andMe that they add this SNP to their screen. Individuals choosing to drink alcoholic beverages may wish to know if they carry one or both of these ADH1 alleles.

But which alcoholic beverage? Beer is clearly a bad mix if you have both alleles of rs1230025. I’m sure that the European brewing community is none too pleased with Dr. Duell’s group.

However, the team may indeed be the toast of the wine and liquor industries.


Creating better protective clothing for firefighters

A University of Alberta professor has been developing a model for protective clothing that may make firefighters’ jobs safer.

Current testing methods and standards of systems for don’t take into account stored thermal energy, which can sometimes leads to second-degree burns, says protective clothing expert Guowen Song of the Department of Human Ecology.

His research sought to understand the phenomenon, measure it and incorporate it into a standard in order to predict as precisely as possible the performance of a clothing system and give a true textile protective performance, or TPP, value.

“Normally, people using a regular approach to testing the clothing’s performance ignore thermal stored energy,” he explains. “They assume they’re predicting clothing performance but they’re actually not.”

While conducting his research, Song noticed energy was released when protective clothes were cooling after having been in a very hot environment.

“[The energy released] was huge,” he says, “especially for the thicker layered systems, like those worn by firefighters.”

He adds that when the contribution of stored energy is considered, the performance of the clothing system is much lower than had been assumed from the TPP value.

For example, the National Firefighters Protection Association has set a fundamental requirement that protective clothing for firefighters has a minimum TPP value of 35, which means the clothes can protect a person engulfed in a fire for 17.5 seconds. However, if you add the stored thermal energy variable to the equation, that time is reduced to about 12 seconds.

“It significantly changes the results,” concludes Song. “The thermal stored energy can release to the human skin even after exposure. That’s why people feel like they got burned or injured after the accident or incident. That’s why burns sometimes occur later when they rest, take off their clothing and suddenly feel pain. That’s the contribution from the thermal stored energy.”

Song is working with the American Society for Testing and Materials to incorporate his findings into the voluntary standards established by the society and lead to better and more efficient protective clothing systems for firefighters.

Provided by University of Alberta (news : web)