Scientists have discovered that a polymer can provide a key to get into tumors

Immunofluorescence image shows nanoparticles targeted to endothelial cells. The red particles turn orange when overlapping with the green caveolin in the lipid rafts of the cells. Source: Julia Voigt / Prasad Shastri

This method could usher in a new approach to delivery of drugs in general

Freiburg researchers find purely chemical way to target therapeutic nano-containers to cells

Scientists have discovered that a polymer can provide a key to get into tumors: Prof. Prasad Shastri, Director of the Institute of Macromolecular Chemistry and core member of the cluster of excellence BIOSS Centre for Biological Signalling Studies at the University of Freiburg, and graduate students Julia Voigt and Jon Christensen have developed a new paradigm to home nanoparticles, containers that measure a few 100 nanometers in size, to endothelial cells. Using just charged polymers with the right affinity for cell lipids the team has developed nanoparticles that can recognize specific cell types simply by their chemical properties. “This is a remarkable discovery, as it allows for the first time to target a specific cell type purely through biophysical principles, and without using the traditional ligand-receptor approach” says Prof. Shastri who led the study that was selected as cover article of the Proceedings of the National Academy of Sciences. Until now researchers placed molecules on nanoparticles that can latch onto proteins on cell surface – called receptors.

These receptors act as an address or a biological postal code. However in tumors these addresses can change rapidly with time. To solve this lack of precision Shastri and team developed particles that are delivered to endothelial cells using a biophysical approach. “This delivery approach does not require a biological postal code for targeting of nanoparticles and is an important step forward in developing nanoparticle based systems for treating cancers” says Julia Voigt the lead author of the paper.

Cancers are very hungry tissues and they need constant nourishment. This is provided through their own supply of blood vessels. “By going after endothelial cells that make up these blood vessels, we can starve the tumor or kill it with one payload” says Jon Christensen who is a co-author on this study and works on tumor metastasis.

Nanoparticles are used to deliver therapeutics in treating cancers. These very small pills, cornerstones of nanomedicine, get injected into the body and reach the tumor cells via the bloodstream. When they find the targeted cells, they need to be eaten so that the drug can act within the cell.

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Polymer Ribbons for Better Healing

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Freiburg researchers develop hydrogels for tissue regeneration that can be fine-tuned to fit any body part

A new kind of gel that promotes the proper organization of human cells was developed by Prof. Prasad Shastriof the Institute of Macromolecular Chemistry and BIOSS Centre for Biological Signalling Studies Excellence Cluster at the University of Freiburg and BIOSS Centre for Biological Signalling Studies graduate studentsAurelien Forget and Jon Christensen in collaboration with Dr. Steffen Lüdeke of the Institute for Pharmaceutical Sciences.

These hydrogels made of agarose, a polymer of sugar molecules derived from sea algae, mimic many aspects of the environment of cells in the human body. They can serve as a scaffold for cells to organize in tissues. In the cover article of the Proceedings of the National Academy of Sciences Prof. Shastri and co-workers show how by applying these hydrogels they could grow blood vessel structures from cells in an unparalleled way. These gels could be used in the future to help damaged tissue heal faster.

The cells environment in the body is composed of collagen and polymers of sugars. It provides mechanical signals to the cells, necessary for their survival and proper organization into a tissue, and hence essential for healing. A gel can mimic this scaffold. However it has to precisely reproduce the molecular matrix outside the cell in its physical properties. Those properties, like the matrices stiffness, vary in the body depending on the tissue.

The team of Prof. Shastri modified agarose gels by adding a carboxylic acid residue to the molecular structure of the polymer to optimally fit the cells environment. Hydrogels form when polymer chains that can dissolve in water are crosslinked. In an agarose gel the sugar chains organize into a spring-like structure. By adding a carboxylic acid to this backbone, the polymers form ribbon-like structures – this allows for the stiffness of the gel to be tuned to adapt the scaffold to every part of the human body.

To demonstrate the versatility of the gel the researchers manipulated endothelial cells that make up vascular tissue to organize into blood vessels outside the body. By combining the appropriate biological molecules found in a developing embryo, they identified a single condition that encourages endothelial cells to form large blood vessel-like structures, several hundred micrometers in height. This discovery has implications in treating damage to heart and muscle tissue.

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via Albert-Ludwigs-Universität Freiburg
 

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The Graphene-Paved Roadmap: ‘Wonder Material’ Has Potential to Revolutionize Our Lives

Has the potential to revolutionise diverse applications from smartphones and ultrafast broadband to anticancer drugs and computer chips

Wonder material graphene could not only dominate the electronic market in the near future, it could also lead to a huge range of new markets and novel applications, a landmark University of Manchester paper claims.

Writing in Nature, Nobel Prize-winner Professor Kostya Novoselov and an international team of authors has produced a ‘Graphene Roadmap’ which for the first time sets out what the world’s thinnest, strongest and most conductive material can truly achieve.

The paper details how graphene, isolated for the first time at The University of Manchester by Professor Novoselov and colleague Professor Andre Geim in 2004, has the potential to revolutionise diverse applications from smartphones and ultrafast broadband to anticancer drugs and computer chips.

One key area is touchscreen devices, such as Apple’s iPad, which use indium tin oxide. Graphene’s outstanding mechanical flexibility and chemical durability are far superior. Graphene touchscreen devices would prove far more long-lasting and would open a way for flexible devices.

The authors estimate that the first graphene touchscreen devices could be on the market within three to five years, but will only realise its full potential in flexible electronics applications.

Rollable e-paper is another application which should be available as a prototype by 2015 — graphene’s flexibility proving ideal for fold-up electronic sheets which could revolutionise electronics.

Timescales for applications vary greatly upon the quality of graphene required, the report claims. For example, the researchers estimate devices including photo-detectors, high-speed wireless communications and THz generators (for use in medical imaging and security devices) would not be available until at least 2020, while anticancer drugs and graphene as a replacement for silicon is unlikely to become a reality until around 2030.

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via Science Digest
 

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