Sea urchin holds key to getting minerals from animals

November 1st, 2008 - 3:42 pm ICT by IANS  

Washington, Nov 1 (IANS) Mammal teeth and bones, protective shells of molluscs and needle-sharp spines of sea urchins are made from scratch by nature.The materials of which shells, teeth and bones are composed are the strongest and most durable in the animal world, and scientists and engineers have long sought to mimic them.

Now, biomineralisation may be closer to reality. An international team of scientists has detailed a key and previously hidden mechanism to transform amorphous calcium carbonate into calcite, the stuff of seashells.

A group led by University of Wisconsin-Madison (UWM) physicist Pupa Gilbert described how the lowly sea urchin transforms calcium carbonate - the same material that forms “lime” deposits in pipes and boilers - into the crystals that make up the flint-hard shells and spines of marine animals.

“If we can harness these mechanisms, it will be fantastically important for technology,” argued Gilbert. “This is nature’s bottom-up nanofabrication. Maybe one day we will be able to use it to build microelectronic or micromechanical devices.”

Gilbert, working with colleagues from Israel’s Weizmann Institute of Science, University of California at Berkeley and the Lawrence Berkeley National Lab, used a novel microscope that employs the soft-X-rays produced by synchrotron radiation to observe how the sea urchin builds its spicules, the sharp crystalline “bones” that constitute the animal’s endoskeleton at the larval stage.

Similar to teeth and bones, the spicule is a biomineral, a composite of organic material and mineral components that the animal synthesises from scratch, using the most readily available elements in sea water: calcium, oxygen and carbon.

The fully formed spicule is composed of a single crystal with an unusual morphology. It has no facets and within 48 hours of fertilisation assumes a shape that looks very much like the Mercedes-Benz logo, according to an UWM statement.

Knowing the step-by-step process may permit researchers to develop new crystal structures that can be used in applications ranging from new microelectronic devices to medical applications, said Gilbert.

These findings were reported in the Oct 27 issue of the Proceedings of the National Academy of Sciences.

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