Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Molecular Self-Assembly Technique May Mimic how Cells Assemble Themselves

21.02.2003


Researchers from the University of Pennsylvania and the University of Sheffield report in the Feb. 21 issue of Science that they have created tree-like molecules that assemble themselves into precisely structured building blocks of a quarter- million atoms. Such building blocks may be precursors to designing nanostructures for molecular electronics or photonics materials, which "steer" light in the same way computer chips steer electrons.

Virgil Percec, the P. Roy Vagelos Chair and Professor of Chemistry at the University of Pennsylvania, and his colleagues also provide chemists with pointers for designing variations of the tree-like molecules to form even larger-scale structures. The work is funded by the Engineering and Physical Sciences Research Council in the United Kingdom and the U.S. National Science Foundation, an independent federal agency that supports fundamental research in all fields of science and engineering.

"Percec and his collaborators have developed a model that may mimic what happens in cell self-assembly," said Andrew Lovinger, NSF program officer. "This is the first time where you get large- scale supramolecular structures to assemble themselves into such exceptionally large and complex structures."



The goal of photonics is to control light the way electronics control and use electrons. A working photonics crystal would have to be approximately as large as the light’s wavelength-on the order of hundreds or thousands of nanometers-yet precisely structured to have predictable and reproducible interactions with the light. The techniques developed by Percec and colleagues may help chemists design self-assembling materials that approach photonics size.

"Photonics crystals require repeating units whose size is in the range of the wavelength of light," Percec said. "So far, we’re the only ones who can design with the precision of atoms but at a nanometer scale. This sort of precision and behavior is previously unknown in organic chemistry."

The researchers start with tree-like organic molecules, called dendrons, each of which is roughly cone-shaped. Twelve of the dendrons assemble themselves into 8,500-atom spheres. Once assembled, the spheres become a "liquid crystal," a material that flows like a liquid but has some properties of a crystalline solid. Liquid crystals are commonly found in flat-panel computer screens and many other devices.

In the right conditions, liquid crystal molecules "pack" themselves into very regular, repeating patterns, called lattices. A common lattice structure resembles neatly stacked layers of golf balls in a box. However, instead of packing into common lattices, the spheres created by Percec’s team arrange themselves into much more complex formations.

"We created extremely large objects that pack into the most complex lattices rather than the simplest ones that everyone expected," Percec said. "They have lattices that we haven’t seen before with organic molecules. They behave like heavy atoms, with a hard core and a soft outer part, like the electron clouds surrounding metals such as uranium."

Because they are constructed from dendrons, the spheres aren’t solid, but instead have a brush-like surface composed of the dendrons’ "branches." The brush-like surface allows the spheres to deform slightly and fill space more like soap bubbles than like golf balls. However, the spheres are firm enough to create repetitive lattices.

In this case, the repetitive "building block," or unit cell, comprises 30 spheres-more than 250,000 atoms-in a rectangular volume nearly 20 nanometers by 10 nanometers. For comparison, the rhinoviruses responsible for many human colds have diameters of about 25 nanometers. The Science paper provides pointers that may allow chemists to make even larger spheres that will pack into more complex lattices that are large enough to scatter light.


NSF Science Expert: Andrew J. Lovinger, 703-292-4933, alovinge@nsf.gov
Principal Investigator: Virgil Percec, 215-573-5527, percec@sas.upenn.edu

NSF is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of nearly $5 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives about 30,000 competitive requests for funding, and makes about 10,000 new funding awards. NSF also awards over $200 million in professional and service contracts yearly.

Julie A. Smith | NSF
Further information:
http://www.nsf.gov
http://www.nsf.gov/od/lpa/
http://www.fastlane.nsf.gov/a6/A6Start.htm

More articles from Life Sciences:

nachricht Nesting aids make agricultural fields attractive for bees
20.07.2017 | Julius-Maximilians-Universität Würzburg

nachricht The Kitchen Sponge – Breeding Ground for Germs
20.07.2017 | Hochschule Furtwangen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

Leipzig HTP-Forum discusses "hydrothermal processes" as a key technology for a biobased economy

12.07.2017 | Event News

 
Latest News

Researchers create new technique for manipulating polarization of terahertz radiation

20.07.2017 | Information Technology

High-tech sensing illuminates concrete stress testing

20.07.2017 | Materials Sciences

First direct observation and measurement of ultra-fast moving vortices in superconductors

20.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>