Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic nanocubes self-assemble into helical superstructures

05.09.2014

Materials made from nanoparticles hold promise for myriad applications, from improved solar energy production to perfect touch screens. The challenge in creating these wonder-materials is organizing the nanoparticles into orderly arrangements.

Nanoparticles of magnetite, the most abundant magnetic material on earth, are found in living organisms from bacteria to birds. Nanocrystals of magnetite self-assemble into fine compass needles in the organism that help it to navigate.


This image depicts an illustration of helices.

Credit: UIC/Megan Strand

Collaborating with nanochemists led by Rafal Klajn at the Weizmann Institute of Science in Israel, who found that magnetite nanocubes can self-assemble into helical superstructures under certain conditions, University of Illinois at Chicago theoretical chemist Petr Kral and his students simulated the phenomenon and explained the conditions under which it can occur. The joint study is online in Science Express in advance of print in the Sept. 5 issue of Science.

The Weizmann researchers dissolved the nanocrystals and exposed the solution to an external magnetic field. As the solution evaporated, helical chains of nanoparticles formed. Surprisingly, the spiral helices were chiral -- that is, either left- or right-handed -- despite the fact that the nanoparticles themselves are not chiral. Densely packed assemblies of helices tended to adopt the same handedness.

Kral's UIC team modeled the self-assembly to determine how helices formed in their collaborators' experiments -- and why the helices had chirality.

They found that the self-assembly into chiral helices is the result of the competing forces acting on them — Zeeman force from the external magnetic field, dipole-dipole magnetic force, magneto-anisotropic directional force, weakly attractive van der Waals forces, and others. The chemistry of the nanoparticle ligands, the solvent, and temperature may also play a role.

In the presence of an external magnetic field, the superparamagnetic nanocubes — which are randomly magnetic and can flip with temperature changes — became tiny magnets with different symmetries of the competing forces acting between them. As a result, when two cubes are face-to-face, they tend to tilt with respect to each other, forming a small angle to the right or left — the seed of a chiral helix, as more nanocubes line up with the first two.

Kral's analysis used a Monte Carlo computer algorithm, which relies on repeated random sampling, running simulations many times over.

"We had to write a new, efficient Monte Carlo computer code describing all the necessary terms, all the values, and then explain how the highly unusual behavior that Klajn observed – the helices' self-assembly – happens," Kral said.

###

Gurvinder Singh of the Weizmann Institute is first author of the paper. Elijah Gelman of the Weizmann Institute, and Henry Chan, Artem Baskin and Nikita Repnin of UIC are co-authors on the study.

The work was supported by the Israel Science Foundation grant 1463/11, the G. M. J. Schmidt-Minerva Center for Supramolecular Architectures, the Minerva Foundation with funding from the Federal German Ministry for Education and Research, National Science Foundation Division of Materials Research grant 1309765 and the American Chemical Society Petroleum Research Fund grant 53062-ND6.

Jeanne Galatzer-Levy | Eurek Alert!
Further information:
http://www.uic.edu

Further reports about: Magnetic Nanocrystals UIC conditions magnetite nanoparticles self-assemble temperature tiny

More articles from Materials Sciences:

nachricht A hydrophobic membrane with nanopores for highly efficient energy storage
22.07.2016 | DWI - Leibniz-Institut für Interaktive Materialien

nachricht New reaction for the synthesis of nanostructures
21.07.2016 | Institute of Chemical Research of Catalonia (ICIQ)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Mapping electromagnetic waveforms

Munich Physicists have developed a novel electron microscope that can visualize electromagnetic fields oscillating at frequencies of billions of cycles per second.

Temporally varying electromagnetic fields are the driving force behind the whole of electronics. Their polarities can change at mind-bogglingly fast rates, and...

Im Focus: Continental tug-of-war - until the rope snaps

Breakup of continents with two speed: Continents initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. The final speed can be up to 20 times faster than in the first, slow extension phase.phases

Present-day continents were shaped hundreds of millions of years ago as the supercontinent Pangaea broke apart. Derived from Pangaea’s main fragments Gondwana...

Im Focus: A Peek into the “Birthing Room” of Ribosomes

Scaffolding and specialised workers help with the delivery – Heidelberg biochemists gain new insights into biogenesis

A type of scaffolding on which specialised workers ply their trade helps in the manufacturing process of the two subunits from which the ribosome – the protein...

Im Focus: New protocol enables analysis of metabolic products from fixed tissues

Scientists at the Helmholtz Zentrum München have developed a new mass spectrometry imaging method which, for the first time, makes it possible to analyze hundreds of metabolites in fixed tissue samples. Their findings, published in the journal Nature Protocols, explain the new access to metabolic information, which will offer previously unexploited potential for tissue-based research and molecular diagnostics.

In biomedical research, working with tissue samples is indispensable because it permits insights into the biological reality of patients, for example, in...

Im Focus: Computer Simulation Renders Transient Chemical Structures Visible

Chemists at the University of Basel have succeeded in using computer simulations to elucidate transient structures in proteins. In the journal Angewandte Chemie, the researchers set out how computer simulations of details at the atomic level can be used to understand proteins’ modes of action.

Using computational chemistry, it is possible to characterize the motion of individual atoms of a molecule. Today, the latest simulation techniques allow...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

GROWING IN CITIES - Interdisciplinary Perspectives on Urban Gardening

15.07.2016 | Event News

SIGGRAPH2016 Computer Graphics Interactive Techniques, 24-28 July, Anaheim, California

15.07.2016 | Event News

Partner countries of FAIR accelerator meet in Darmstadt and approve developments

11.07.2016 | Event News

 
Latest News

Hey robot, shimmy like a centipede

22.07.2016 | Information Technology

New record in materials research: 1 terapascals in a laboratory

22.07.2016 | Physics and Astronomy

University of Graz researchers challenge 140-year-old paradigm of lichen symbiosis

22.07.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>