Tuesday, January 17, 2012

Film coatings made from whey

From pre-packed Camembert to shrink-wrapped meat loaf – choosing the right packaging is a key issue in the food industry. Companies need to protect food products from oxygen, moisture and chemical and biological contamination while keeping them fresh for as long as possible. Transparent multilayer , in which each layer offers specific benefits, are frequently used to protect food from contamination. To minimize the amount of oxygen that penetrates the packaging, companies typically use expensive, petrochemical-based polymers such as ethylene vinyl alcohol (EVOH) copolymers as barrier materials. The German Society for Packaging Market Research (Gesellschaft für Verpackungsmarktforschung mbH) estimates that more than 640 square kilometers of composite materials employing EVOH as an oxygen barrier layer will be produced and used in Germany in 2014 – enough to completely cover Lake Constance. There is therefore a strong impetus to develop a sustainable packaging material which is both economical to produce and environmentally friendly. Researchers working on the EU’s “Wheylayer” project have been using whey instead of petrochemical-based polymers. The natural ingredients in the whey extend the shelf life of food products, and the whey protein layer is biodegradable. The results of the research are promising. “We’ve managed to develop a whey protein formulation that can be used as the raw material for a film barrier layer. And we have also developed an economically viable process which can be used to produce the multifunctional films on an industrial scale,” says Markus Schmid from the Fraunhofer Institute for Process Engineering and Packaging IVV in Freising.

But how is it even possible to make a barrier layer from whey? The researchers from the IVV began by purifying sweet whey and sour whey and producing high purity whey protein isolates. They tested a range of different modification methods in order to obtain suitable proteins with outstanding film-forming properties. To enable these proteins to withstand the mechanical loads involved, they were subsequently mixed with differing concentrations of various softeners and other additives, which were also biobased. “All these additives are approved substances,” says Schmid. The search for the perfect formula was a tricky process for the Freising-based researchers. For example, use too many softeners and the barrier effect against water vapor and oxygen decreases, which means that the food is no longer adequately protected. In the end, the researchers not only found the optimum formula, but also came up with a suitable, economically viable and industrial-scale method of applying whey protein coatings to plastic films and combining these with other films using different technologies. The overall process produces multilayer structures with barrier functions which can be used to produce flexible, transparent food packaging materials. “Our work at the IVV to manufacture a multilayer film of this kind using a roll-to-roll method is a world’s first,” Schmid notes. Companies that choose to make the switch to whey proteins in the future will only need to make minor modifications to their plants. The researchers have already applied for a patent on their new technology.

The IVV researchers are so convinced of whey proteins’ future potential as an alternative packaging material that they have initiated their own project which goes one step further. According to a survey carried out by the German Society for Packaging Market Research, there is not only an increasing demand for composite films, but also an increasing need for thermoformable composites. Growing demand for prepared products in trays is expected to increase the volume of these composites from 76,497 tons in 2009 to 93,158 tons in 2014. The researchers are working hard to replace EVOH in thermoform composites with a barrier layer based on whey protein. This additional application for whey protein would likewise conserve resources and reduce the emission of carbon dioxide into the atmosphere.

Provided by Fraunhofer-Gesellschaft (news : web)

Extracellular matrix could lead to advances in regenerative medicine

NPL scientists have created a functional model of the native extracellular matrix which provides structural support to cells to aid growth and proliferation and could lead to advances in regenerative medicine.

The extracellular matrix (ECM) provides the physical and chemical conditions that enable the development of all biological tissues. It is a complex nano-to-microscale structure made up of protein fibres and serves as a dynamic substrate that supports tissue repair and regeneration.

Human-made structures designed to mimic and replace the native matrix in damaged or diseased tissues are highly sought after to advance our understanding of tissue organisation and to make regenerative medicine a reality.

Self-assembling peptide fibres that have similar properties to those of the native matrices are of particular interest. However, these near-crystalline nanostructures fail to arrange themselves into interconnected meshes at the microscopic scale, which is critical for bringing cells together and supporting tissue development.

To solve this problem, a research team at NPL designed a small protein consisting of two complementary domains (structural units) that promote the formation of highly branched networks of fibres that span microscopic dimensions. The team showed that the created matrix is very efficient in supporting cell attachment, growth and proliferation.

This research is part of the NPL-led international research project, 'Multiscale measurements in biophysical systems', which is jointly funded by NPL and the Scottish Universities Physics Alliance.

Read the full article detailing this research published in Angewandte Chemie -- the premier and most authoritative publication for critical advances in chemical research.

Story Source:

The above story is reprinted from materials provided by National Physical Laboratory.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Angelo Bella, Santanu Ray, Michael Shaw, Maxim G. Ryadnov. Arbitrary Self-Assembly of Peptide Extracellular Microscopic Matrices. Angewandte Chemie International Edition, 2011; DOI: 10.1002/anie.201104647

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

How do you mend a broken heart?

"Despite advances in modern medicine, management of myocardial infarction and heart failure remains a major challenge," explains senior study author Dr. Tao P. Zhong from Fudan University in Shanghai, China. "There is intense interest in developing agents that can influence stem cells to differentiate into cardiac cells as well as enhance the inherent regenerative capacities of the heart. Developing therapies that can stimulate heart muscle regeneration in areas of infarction would have enormous medical impact."

To search for new molecules involved in heart development, Dr. Zhong and colleagues developed a robust small molecule screen using a zebrafish system. The zebrafish is an excellent model organism to study heart growth and development because there are established genetic approaches that permit visualization of fluorescent beating hearts within transparent embryos. After screening nearly 4,000 compounds, the researchers discovered three structurally related molecules that could selectively enlarge the size of the embryonic heart. The compounds, cardionogen-1, -2, and -3, could promote or inhibit heart formation, depending on when they were administered during development.

Cardionogen treatment enlarged the zebrafish heart by stimulating production of new cardiac muscle cells from stem cells. The researchers went on to show that cardionogen could stimulate mouse embryonic stem cells to differentiation into beating . The effects of cardionogen were linked to Wnt signaling, a pathway best known for its role in embryonic and heart development. Cardionogen opposes Wnt signaling to induce cardiac muscle cell formation. Importantly, the interaction of cardionogen with Wnt seemed to be restricted to specific cell types.

Taken together, the results identify the cardionogen family members as important modulators of cardiac muscle cell development. "Evaluating the potential of cardionogen on human adult and embryonic is the next logical step," concludes Dr. Zhong. "This may ultimately aid in design of therapeutic approaches to enhance repopulation of damaged heart muscle and restore function in diseased hearts."

More information: DOI:10.1016/j.chembiol.2011.09.015

Provided by Cell Press (news : web)

One of the most porous materials ever discovered

 The delivery of pharmaceuticals into the human body or the storage of voluminous quantities of gas molecules could now be better controlled, thanks to a study by University of Pittsburgh researchers. In a paper published online January 4 in Nature Communications, a team of chemists and colleagues from Pitt's Kenneth P. Dietrich School of Arts and Sciences and the Pitt School of Medicine and Northwestern and Durham universities have posed an alternative approach toward building porous materials.

Working with metal-organic frameworks -- crystalline compounds comprising metal- cluster vertices linked together by organic molecules to form one-, two-, or three-dimensional porous structures -- researchers addressed changing the size of the vertex (the metal cluster) rather than the length of the organic molecule links, which resulted in the largest metal organic framework pore volume reported to date.

"Think of this the way you imagine Tinkertoys®," said Nathaniel Rosi, principal investigator and assistant professor in Pitt's Department of Chemistry in the Dietrich School. "The metal clusters are your joints, and the organic molecules are your linkers. In order to build a highly open structure with lots of empty space, you can increase the linker length or you can increase the size of the joint. We developed chemistry to make large joints, or vertices, and showed that we could link these together to build a material with extraordinarily large pores for this class of materials.

"Essentially, we're like architects. We first make a blueprint for a target material, and we then select our building blocks for construction," added Rosi. "We develop methods for designing structures and controlling the assembly of these structures on a molecule-by- molecule basis."

Rosi and Jihyun An, who graduated with a PhD degree in chemistry from Pitt in 2011 and is lead author of the paper, said this new approach could have an impact on storing large quantities of gas such as carbon dioxide or methane, an important development for alternative energy, or large amounts of drug molecules, which could impact the drug-delivery field. Since joining Pitt five years ago, Rosi has developed a lab that includes students and postdoctoral researchers from various chemistry-related disciplines and focuses on new methods for materials' design and discovery.

The team's research has been supported by Pitt and the American Chemical Society Petroleum Research Fund.

Story Source:

The above story is reprinted from materials provided by University of Pittsburgh.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Jihyun An, Omar K. Farha, Joseph T. Hupp, Ehmke Pohl, Joanne I. Yeh, Nathaniel L. Rosi. Metal-adeninate vertices for the construction of an exceptionally porous metal-organic framework. Nature Communications, 2012; 3: 604 DOI: 10.1038/ncomms1618

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

Nanotechnology: Nanomechanical measurements of unprecedented resolution made on protein molecules

UCLA physicists have made nanomechanical measurements of unprecedented resolution on protein molecules.

The new measurements, by UCLA physics professor Giovanni Zocchi and former UCLA physics graduate student Yong Wang, are approximately 100 times higher in resolution than previous mechanical measurements, a nanotechnology feat which reveals an isolated protein molecule, surprisingly, is neither a solid nor a liquid.

"Proteins are the molecular machines of life, the molecules we are made of," Zocchi said. "We have found that sometimes they behave as a solid and sometimes as a liquid.

"Solids have a shape while liquids flow -- for simple materials at low stresses. However, for complex materials, or large stresses, the behavior can be in-between. Subjected to mechanical forces, a material might be elastic and store mechanical energy (simple solid), viscous and dissipate mechanical energy (simple fluid), or visco-elastic and both store and dissipate mechanical energy (complex solid, complex fluid). The viscoelastic behavior characteristic of more complex matter had not been clearly seen before on isolated proteins because mechanical measurements tend to destroy the proteins."

Zocchi and Wang's new nanotechnology method allowed them to apply stresses and probe the mechanics of the protein without destroying it. Wang, now a physics postdoctoral fellow at the University of Illinois in Urbana-Champaign, and Zocchi discovered a "transition to a viscoelastic regime in the mechanical response" of the protein.

"Below the transition, the protein responds elastically, like a spring," Zocchi said. "Above the transition, the protein flows like a viscous liquid. However, the transition is reversible if the stress is removed. Functional conformational changes of enzymes (changes in the shape of the molecule) must typically operate across this transition."

The measurements were performed on the enzyme guanylate kinase, or GK, a member of an essential class of enzymes called kinases. Specifically, GK transfers a phosphate group from ATP (the universal "fuel" of the cell) to GMP, producing GDP, an essential metabolic component, Zocchi said.

The study on the characterization of the "visco-elastic transition" is reported this month in the online journal PLoS ONE, a publication of the Public Library of Science. The research was federally funded by the National Science Foundation's division of materials research and by a grant from the University of California Lab Research Program.

Zocchi and Wang published related findings earlier this year in the journal Europhysics Letters, a publication of the European Physical Society, and the journal Physical Review Letters.

In previous research, Zocchi and colleagues reported a significant step in controlling chemical reactions mechanically last year, made a significant step toward a new approach to protein engineering in 2006, created a mechanism at the nanoscale to externally control the function and action of a protein in 2005, and created a first-of-its-kind nanoscale sensor using a single molecule less than 20 nanometers long in 2003. A nanometer is roughly 2,000 times smaller than the width of a human hair.

The above story is reprinted from materials provided by University of California - Los Angeles. The original article was written by Stuart Wolpert.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Yong Wang, Giovanni Zocchi. Viscoelastic Transition and Yield Strain of the Folded Protein. PLoS ONE, 2011; 6 (12): e28097 DOI: 10.1371/journal.pone.0028097

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