11-10 :: October 2011

nanotimes News in Brief

Andreas Stampfl, Melanie Maier, Roman Radykewicz, Peter Reitmeir, Martin Göttlicher, Reinhard Niessner Lan- gendorff Heart: A Model System To Study Cardiovascular Effects of Engineered Nanoparticles, In: ACS Nano, Vol. 5(2011), Issue 7, July 26, 2011, Pages 5345-5353, DOI:10.1021/nn200801c: http://dx.doi.org/10.1021/nn200801c

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self-assembly. The coating polymer has the added benefit that other molecules can be bound to it. Another important plus is that it does not adversely affect the quantum dot‘s light-emitting properties.

Dominik Janczewski, Nikodem Tomczak, Ming-Yong Han & G. Julius Vancso: Synthesis of functionalized am- phiphilic polymers for coating quantum dots, In: Nature Protocols, Vol. 6, No. 10, October 2011, Pages 1546- 1553, DOI:10.1038/nprot.2011.381: http://dx.doi.org/10.1038/nprot.2011.381

Researchers at the University of Twente’s MESA+ Institute for Nanotechnology and at the A*STAR agency in Singapore have developed a coating which allows quantum dots to be used inside the human body, even inside living cells. The new coa- ting enables quantum dots, which are semiconduc- tor nanocrystals, to literally cast light on biological processes.

Scientists studying biological processes often use fluorescent tags that bind to biomolecules. This makes it relatively easy to track such molecules, even inside living cells. Quantum dots are a better option. They emit long-lasting, bright light, the co- lour of which depends on the size of the quantum dots used. For a number of reasons, including their toxicity, they were previously unsuitable for use in living organisms. The researchers therefore deve- loped an amphiphilic coating, i.e. one with both hydrophobic and hydrophilic properties. The “water hating” side of the polymer material attaches to the surface of the quantum dot. Its exposed hydrophilic side then makes the quantum dot/coating combi- nation soluble in water. The coating builds up on the surface of the quantum dot through a process of

Cornell researchers propose an approach from chemistry to self-assemble metamaterials in three dimensions. Uli Wiesner, the Spencer T. Olin Professor of Engineering, and colleagues present their idea in the online edition of the journal Ange- wandte Chemie. Wiesner‘s research group offers a method they have pioneered in other fields, using block copolymers to self-assemble 3-D structures with nanoscale features.

A polymer is made up of molecules that chain to- gether to form a solid or semisolid material. A block copolymer is made by joining two polymer mole- cules at the ends so that when each end chains up with others like itself, the two solids form an inter- connected pattern of repeating geometric shapes -- planes, spheres, cylinders or a twisty network called a gyroid. Elements of the repeating pattern can be as small as a few nanometers across. Sometimes tri- polymers can be used to create even more complex shapes.