Planet–satellite nanostructures from gold nanoparticles and RAFT star polymers
The cosmos in miniature: German researchers have produced nanoparticles surrounded by a group of smaller nanoparticles like a planet orbited by satellites.
They equipped larger gold nanoparticles with special star-shaped polymers, which in turn bind to smaller gold nanoparticles. As the researchers report in the journal Angewandte Chemie, it is possible to precisely control the distance between the tiny “satellites” and their central “planet” by means of the molecular weight—and thus the chain length—of the polymers.
Like all humans, researchers like good aesthetics. They take pleasure in unusual nanoscopic architectures with ordered structures and are curious about what interesting physical properties are inherent to such structures. These properties can often be extremely useful.
For example, nanoarchitectures consisting of a central nanoparticle surrounded by smaller nanoparticles at a precisely defined distance could be used as sensors, as “rulers” for measuring biological nano-objects, and as transport systems to deliver drugs specifically to tumor cells. However, researchers had not previously found a method to easily and efficiently produce a variety of planet–satellite nanosystems—a critical requirement for the investigation and practical use of such nanoarchitectures.
Christin Rossner and Philipp Vana at the University of Göttingen have now developed such a technique. At its center are polymers produced by a RAFT (reversible addition–fragmentation chain transfer) polymerization. RAFT is a technique for the targeted synthesis of polymers with a precisely defined degree of polymerization; it results in very uniform polymers with precisely controllable chain lengths.
Because this is a controlled process, it is also possible to synthesize more complicated molecular architectures, such as comb-shaped or star-shaped polymers. Rossner and Vana chose to use star polymers consisting of a center with four side chains coming out like rays. The side chains have trithiocarbonate groups at their ends. These groups bind very well to gold surfaces.
The researchers treated gold nanoparticles with these star polymers. Two to three of the “rays” bind to the surface while the remaining one or two rays remain free and available to bind the smaller satellite gold nanoparticles later. The molecular weight of the star polymers—and thus the length of the rays—can be used to precisely control the distances between the planets and satellites. The satellites can also be equipped with polymer chains that have certain chemical groups on their ends. It is thus possible to make gold nanoparticle scaffolds with a variety of reactive groups at a defined distance form the central core.
About the Author
Dr. Philipp Vana is Professor of Macromolecular Chemistry at the University of Göttingen. His research focuses on tailoring macromolecules and nanocomposites using controlled polymerizations and on the design of new functional polymers. He is also Director of the Institute of Physical Chemistry in Göttingen and has been awarded several prizes and fellowships including the prestigious Heisenberg Professorship of the DFG.
Author: Philipp Vana, Universität Göttingen (Germany), http://www.mmc.chemie.uni-goettingen.de/
Title: Planet–Satellite Nanostructures Made To Order by RAFT Star Polymers
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201406854
Philipp Vana | Angewandte Chemie
Good preparation is half the digestion
15.11.2018 | Max-Planck-Institut für Stoffwechselforschung
How the gut ‘talks’ to brown fat
16.11.2018 | Technische Universität München
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Physics and Astronomy
16.11.2018 | Physics and Astronomy
16.11.2018 | Life Sciences