Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Oh the Shark Has Pretty Teeth Dear…

24.01.2014
Atomic resolution imaging of fluorine in shark tooth enamel

Shark teeth are supposedly the healthiest of all animals because of their particularly hard enamel. Japanese researchers have now been able to use a special electron microscopy technique to image the structure of shark enamel.



In the journal Angewandte Chemie, they report on an unusually strong bond between fluorine atoms and calcium atoms, which may be responsible for the unusual hardness and cavity resistance of shark teeth.

Biominerals play an important role for all life forms. Our own bones and teeth consist of a composite material made from biomolecules and inorganic substances. Shark tooth enamel is mainly fluorapatite (Ca5[F(PO4)3]), a mineral with a hexagonal crystal structure that contains calcium, fluorine, and phosphate. But what is it that makes the shark’s tooth enamel so particularly strong? So far, all we have determined is that it has a high density of fluorapatite crystals and a low content of organic matrix.

Determining the exact structures of biominerals turns out to be distinctly difficult. In the best cases, experiments using transmission electron microscopy have been able to deliver information on the nanometer scale. Advances like aberration correction have improved the resolution of TEM, but the signals are weak and the structures extremely complex.

In addition, the electron beam damages biominerals. A team led by Yuichi Ikuhara has now been able to examine the enamel of shark teeth by TEM and scanning TEM (STEM) with minimum interference. To achieve this, the researchers from Tohoku University, the University of Tokyo, the Graduate School of Tokyo Medical and Dental University, and the Fine Ceramics Center used an aberration-corrected electron microscopy technique that gets by with a very low dose. This method works by using a smaller condenser aperture and dispersing the electron beam over a wider area of the sample than usual.

The scientists were thus able to spatially resolve each individual atom columns inside the complex fluorapatite structure. They found that shark tooth enamel consists of bundles of monocrystalline nanorods of fluorapatite with a diameter of about 50 nm. The hexagonal shape of the crystal could also be confirmed. Every hexagon consists of calcium, phosphorus, and oxygen atoms with a fluorine atom at the center. By using ab initio calculations, the researchers were able to determine that the fluorine atoms are bound to the surrounding calcium atoms with covalent–ionic mixed bonds, not ionic bonds alone as expected. This seems to be the main reason for the special cavity resistance of shark teeth.

About the Author
Dr. Yuichi Ikuhara is a Professor at Tohoku University and the University of Tokyo with appointments in materials science. His main specialty is the application of state-of-the-art transmission electron microscopy to solve fundamental issues in materials science. He is also Director of the Research Hub for Advanced Nano Characterization and Nanotechnology Platform at the University of Tokyo, and is the recipient of the Commendation for Science and Technology by MEXT of Japan and the Humboldt Research Award.

Author: Yuichi Ikuhara, Tohoku University (Japan), http://www.wpi-aimr.tohoku.ac.jp/en/research/researcher/y-ikuhara.html

Title: Fluorine in Shark Teeth: Its Direct Atomic-Resolution Imaging and Strengthening Functio

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201307689

Yuichi Ikuhara | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society

nachricht 127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>