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 Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>