Research leads to enhanced kit to improve design and processing of plastics

The National Physical Laboratory (NPL) has developed a world-leading pvT (pressure-volume-temperature) and thermal conductivity test kit.

The kit is based on more than nine years of extensive research at NPL. It can be used to help improve the design and processing of plastics, including the injection moulding process used to make specialised polymers and everyday plastic items such as CDs

NPL's equipment can measure the thermo-physical properties of polymers. It can help improve the injection moulding process by allowing designers to find the exact pvT and shrinkage properties of a material. Although plastics are the main material tested, other more unusual materials such as soap and even chocolate have also been analysed.

The pvT instrument operates at pressures ranging from 200 bar to 2500 bar, and is the only equipment in the world that can test materials at ultra fast cooling rates of up to 280 °C/min and down to temperatures approaching -100 °C. NPL found that at higher pressures polymers can conduct heat up to 20% more efficiently, leading to faster cooling rates and shorter cycle times.

A thermal conductivity measurement facility is also incorporated into the instrument. Research on the thermal conductivity properties of polymers such as HDPE (high-density polyethylene) and PBT (polybutylene terephthalate) is vital to manufacturers and it was found that they can increase their production rates and gain a higher profit by filling a polymer with glass - as this cools faster, reducing the time that the polymer needs to stay in the mould. The less time the polymer stays in the mould, the faster the output rate of products.

Angela Dawson a Higher Research Scientist for NPL's Materials Division, said:

"pvT testing kits are essential for improving design and processing of ubiquitous, everyday plastics and for more specialised polymers with advanced applications. NPL is the only laboratory where manufacturers can send materials for testing using this advanced equipment and this work has improved the reliability and accuracy of measuring pvT data."

Provided by National Physical Laboratory

Scientists shut down pump action to break breast cancer cells' drug resistance

Breast cancer cells that mutate to resist drug treatment survive by establishing tiny pumps on their surface that reject the drugs as they penetrate the cell membrane – making the cancer insensitive to chemotherapy drugs even after repeated use.

Researchers have found a new way to break that resistance and shut off the pumps by genetically altering those breast cancer cells to forcibly activate a heat-shock protein called Hsp27. This protein regulates several others, including the protein that sets up the pumps that turn away the chemotherapeutics.

In experiments, the common chemotherapy drug Doxorubicin killed about 50 percent more drug-resistant breast cancer cells in which Hsp27 had been activated than it did in normal drug-resistant cells.

Though these results have been shown only in cell cultures in a lab, they suggest that there someday could be a clinical way to use this approach to reverse the drug resistance that can develop in breast cancer cells. The study was conducted in MCF-7/adr breast cancer cells, which resist the effects of Doxorubicin.

"These cells are actually resistant to multiple drugs, so the resistance will be there even if clinicians move on to other chemotherapeutics. It's a serious issue," said Govindasamy Ilangovan, associate professor of internal medicine at Ohio State University and senior author of the research. "The plausible way to circumvent this effect is to suppress the resistance by shutting down the drug extrusion pump using molecular approaches. That is what we're trying to address."

The study appears in the Sept. 23 issue of the Journal of Biological Chemistry.

The researchers analyzed proteins in regular breast cancer cells from the MCF-7 cell line as well as multidrug resistant cells from the same line. The normal breast cancer cells are known to be sensitive to chemotherapy drugs.

The tests indicated that the normal cells contained HSF-1, the transcription factor that activates the heat shock protein Hsp27. However, in the drug-resistant cells, HSF-1 was extremely low and Hsp27 was present in only trace amounts.

Previous research has established that Hsp27 controls two other proteins, including the culprit protein that makes the cells drug resistant by establishing pumps to extrude chemotherapeutics out of cells. This pumping protein's level was clearly high in the drug-resistant cells, and nonexistent in the normal breast cancer cells.

"The existence of this pump-action protein, called P-gp, is bad because it is removing the drugs from the cells. The cells do not even feel the presence of the drug in the system. We need to lower the amount of P-gp so that the drug stays in the cells to cause the intended damage. So we decided to model how to achieve this by forcibly bringing back the Hsp27," said Ilangovan, also an investigator in Ohio State's Davis Heart and Lung Research Institute.

In these experiments on cells, the researchers performed gene transfer using a viral vector to deliver the Hsp27 gene into the drug-resistant cells. As expected, after the addition of this gene the Hsp27 protein was abundantly induced and the drug-resistant protein p-gp went down in the cells.

"Then we tested the cells under this condition to determine whether we could sensitize these resistant cells to the drug," Ilangovan said.

After treatment with varying levels of Doxorubicin, about 50 percent more resistant cells in which Hsp27 had been forcefully activated died compared to normal drug-resistant cells. In addition, fluorescent staining of the cells showed that the expression of Hsp27 in these cells also caused them to absorb much more of the chemotherapy drug – a sign the drug was not being pumped away.

Additional experiments showed that these genetically altered cells died in the way they typically would in response to chemotherapy – by undergoing a programmed cell death process called apoptosis.

"We proved Doxorubicin does kill these cells in the way it is supposed to," Ilangovan said.

The findings represent a twist of sorts in molecular biology because heat-shock proteins typically are activated by stress. But in this case, the drug-resistant cells become reprogrammed over time – presumably, in response to the stress of being treated with drugs intended to kill them – and instead of being full of heat-shock protein activity, those stress-induced proteins are silenced.

"Because these proteins are involved, it looks at present like there could be a strong link between chronic stress and this drug-resistant mechanism evolving in the cells, but we need to carry out additional new studies to make any solid conclusion on chronic stress and drug resistance in cancer," Ilangovan said.

Translation of this technique in humans is years away, but would likely involve the delivery of the Hsp27 gene into drug-resistant cancer cells to induce activation of the Hsp27 protein, he said. The next step in this work involves refining the gene transfer process and demonstrating it in animal models.

More information: http://www.jbc.org/

Provided by The Ohio State University (news : web)

Catalyst discovery potential has to revolutionize chemical industry

University of Alberta Chemistry Professor Steve Bergens and his graduate student Jeremy Johns have discovered a catalyst that has the potential to revolutionise the chemical industry by reducing its environmental footprint, improving efficiency and minimizing risks.

Their findings were published in a top international chemistry journal Angewandte Chemie this month and provide the chemical industry with a potential solution to issues surrounding economics, efficiency and environmental factors.

"Our findings are a game changer that people having been seeking an answer to for decades," said Bergens.

Bergen said researchers have been working for more than 50 years to find a "clean" and stable catalyst that produces little to no waste and also has a capacity to provide multiple turnovers. In February of this year his student Jeremy Johns created such a catalyst in his laboratory.

"After years of producing disappointing results I was thrilled to see the results that came out of this particular experiment," said Dr Bergens.

"The chemical industry is making huge efforts to reduce its environmental footprint and their economists and accountants are also looking to reduce the cost of not just transporting catalyst but improving its efficiency," said Dr Bergens.

He said the February 2011 discovery opens numerous doors to make these things happen for industries ranging from pharmaceuticals to agrochemicals.

"Catalysts are notoriously unstable and challenging to transport, and the waste products the reactions to produce chemicals produce are equally challenging," Bergens added.

John's catalyst only produces hydrogen as a waste, something that is easy to burn off or react to produce water.

Bergens says early indications are the catalyst is not just safe but also efficient. The researchers have pushed the experiment to produce 7000 turnovers for one unit of catalyst.

"We are hugely excited , and the challenge now is to identify exactly how this catalyst is made up and how we can produce it in amounts to further advance this discovery," said Bergens.

Provided by University of Alberta (news : web)

Multi-compartment globular structures assembled from polymer-based materials may soon serve as cell prototypes

The cell is a host of many complex reaction pathways. These pathways usually do not interfere with each other because they are contained within membrane-bound compartments, known as organelles. The lipid membrane is extremely selective—only allowing certain signalling molecules to permeate through—and plays an important role in biological processes, such as protein synthesis and the regulation of enzymatic reactions. Madhavan Nallani from the A*STAR Institute of Materials Research and Engineering and co-workers have now synthesized a new type of multi-compartment structure known as a polymersome, which mimics cellular compartmentalization through the use of self-assembling polymers.

Although many researchers have created artificial structures designed to imitate cells, their efforts have primarily been restricted to lipid and polymer-based structures with only one compartment. Nallani and his team designed a system consisting of two compartments self-assembled sequentially. “Most importantly, the membranes of different compartments are made from different materials,” Nallani says. As a consequence of this unique feature, the properties of the membranes can be tuned.

To make the polymersomes, the team opted for amphiphilic block copolymers—polymers composed of subunits with opposite affinity to water. Nallani explains that this difference in wettability is what drives the copolymers to self-organise into compartments. “One of the challenges that we encountered is the selection of materials to form such architectures,” he adds.

The researchers first synthesized single-compartment particles using one copolymer. They then entrapped each of these first structures in a second shell by adding a solution containing another type of copolymer. In the resulting multi-compartmentalized architectures, the inner particle consisted of a tightly packed, low-permeability membrane and was surrounded by a semi-permeable outer membrane that lets small molecules through.

Nallani and his team tested the selectivity of the compartment membranes for the encapsulation of biomolecules. As a proof of concept, they encased one kind of fluorescent protein that emits green light and another variety that displays red-light emission in the polymersomes. The inner part of the particles emitted green light while the outer compartment emitted red light (see image). The result suggests that the proteins were localized in two separate sections according to their type.

“Our system may add value in applications such as drug delivery and multi-enzyme biosynthesis,” says Nallani. The researchers are currently designing compartments that allow different components to mix just before reaching target cells. They are also introducing membrane proteins within these compartments that may facilitate the transport of products formed in one compartment to another.

More information: Fu, Z., et al. Multicompartmentalized polymersomes for selective encapsulation of biomacromolecules. Chemical Communications 47, 2862–2864 (2011).

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

Orange peels could be made into biodegradable plastic

Plastic waste is one of the worst forms of trash because it takes so long to degrade, thus overflowing our landfills and polluting our oceans and waterways. But what if we could make plastic from a recycled, natural, biodegradable source?

That's the idea behind a new technology developed by British scientists that uses microwaves to turn plant-based waste, such as orange peels, into eco-friendly plastic, according to London's The Independent.

Researchers have created a partnership with the juice-making industry in Brazil and have launched the Orange Peel Exploitation Company to demonstrate the technology on a large scale.

"There are 8 million tonnes of orange residue in Brazil. For every orange that's squeezed to make juice, about half of it is wasted," said James Clark, professor of green chemistry at the University of York in the U.K., and developer of the new approach. "What we've discovered is that you can release the chemical and energy potential of orange peel using microwaves."

The technique works by focusing high-powered microwaves on plant-based material, transforming the tough cellulose molecules of the plant matter into volatile gases. Those gases are then distilled into a liquid that researchers say can be used to make plastic. The process works at 90 percent efficiency, and it can be used on a variety of plant waste beyond orange peels.

Orange peels are particularly good for this technique because they are rich in a key chemical, d-limonene, which is also an ingredient in many cleaning products and cosmetics.

"The unique feature of our microwave is that we work at deliberately low temperatures. We never go above 200 (degrees Celsius). You can take the limonene off or you can turn limonene into other chemicals," he said. "It works really well with waste paper. It can take a big range of bio-waste material," Clark said.

The environmental benefit of this technology goes beyond developing a more biodegradable plastic. It also recycles plant waste which is normally discarded. Farmers, factories and power stations that deal with a lot of excess biomass could be a few of the beneficiaries.

"We are talking to farmers who are already concentrating a lot of biomass for palletizing before going to power stations about the possibility of locating a facility in one of these centralized units," Clark said.

More information: © 2011, Mother Nature Network.
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