February 16, 2012
Structure Of Tough Sea Urchin Spines May Inspire Engineers
A team of German scientists recently decoded the molecular structure of the unusually sturdy spines of sea urchins, a discovery that they believe could eventually prove useful in helping engineers construct stronger, more stable buildings.
Biologists have long known that the spines of the globular little marine animals are made of the compound calcium carbonate, a chemical commonly found in the shells of various invertebrates, not to mention egg shells, calcium supplements and the antacids you take for heartburn.
Like a multipurpose tinker toy, calcium carbonate has the ability to bond with itself and other compounds in numerous ways, making it one of the essential building blocks in nature´s toolkit.
But for researchers looking for an explanation as to why those little sea urchin spines are so remarkably strong, the versatility of the molecule and its numerous possibilities for bonding has long left them scratching their heads.
“Some people were arguing that the spine is a single crystal, and others who were looking at the mechanical properties were arguing that it´s more like a glassy material,” explained the study´s lead researcher Helmut Coelfen from the University of Konstanz in Germany in an interview with the BBC.
Using a variety of techniques, including advanced X-ray crystallography at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, the scientists were able to get a peek into the molecular structure of the spines. The researchers now say that the spines are constructed of two principle parts: “bricks” of crystal calcite (a carbonate mineral) that are held together with a non-crystalline calcium carbonate “mortar”.
Moreover, they say the calcite “bricks” appear to make up about 92 percent of total mass of the spines while the mortar constitutes roughly 8 percent of the structure.
“With the help of these different techniques we were able to understand from the nanometer scale all the way to the millimeter scale how everything is arranged,” Dr. Jong Seto, one of the paper´s co-authors, told BBC.
The incredible strength and resilience of this structure, says Coelfen, could provide humans with yet another opportunity to mimic nature.
“The most obvious application ... is building materials, to get fracture-resistant materials by just copying or trying to copy that building principle,” he said.
In particular he believes the composition and use of concrete could possibly be revolutionized, as numerous industrial research companies around the world continue to search for ways to make the ubiquitous building substance stronger.
“We are already working with two major international companies trying to improve the properties of concrete by trying to order the little nanoparticles in concrete to make it tougher and more fracture-resistant.”
Their report was published this week in the Proceedings of the National Academy of Sciences.
Image Caption: Inside a sea urchin spine. Credit: Marina Krumova, University of Konstanz.
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