Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Sea urchin yields a key secret of biomineralization

Abstract:
The teeth and bones of mammals, the protective shells of mollusks, and the needle-sharp spines of sea urchins and other marine creatures are made-from-scratch wonders of nature.

Used to crush food, for structural support and for defense, 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, harnessing the process of biomineralization may be closer to reality as an international team of scientists has detailed a key and previously hidden mechanism to transform amorphous calcium carbonate into calcite, the stuff of seashells. The new insight promises to inform the development of new, superhard materials, microelectronics and micromechanical devices.

Sea urchin yields a key secret of biomineralization

Madison, WI | Posted on October 27th, 2008

In a report today (Oct. 27) in the Proceedings of the National Academy of Sciences (PNAS), a group led by University of Wisconsin-Madison physicist Pupa Gilbert describes 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. The mechanism, the authors write, could "well represent a common strategy in biomineralization…."

"If we can harness these mechanisms, it will be fantastically important for technology," argues Gilbert, a UW-Madison professor of physics. "This is nature's bottom-up nanofabrication. Maybe one day we will be able to use it to build microelectronic or micromechanical devices."

Gilbert, who worked with colleagues from Israel's Weizmann Institute of Science, the University of California at Berkeley and the Lawrence Berkeley National Laboratory, 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 sea urchin spicule is a biomineral, a composite of organic material and mineral components that the animal synthesizes 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 fertilization assumes a shape that looks very much like the Mercedes-Benz logo.

These crystal shapes, as those of tooth enamel, eggshells or snails, are very different from the familiar faceted crystals grown through non-biological processes in nature. "To achieve such unusual — and presumably more functional — morphologies, the organisms deposit a disordered amorphous mineral phase first, and then let it slowly transform into a crystal, in which the atoms are neatly aligned into a lattice with a specific and regular orientation, while maintaining the unusual morphology," Gilbert notes.

The question the Wisconsin physicist and her colleagues sought to answer was how this amorphous-to-crystalline transition occurs. The sea urchin larval spicule is a model system for biominerals, and the first one in which the amorphous calcium carbonate precursor was discovered in 1997 by the same Israeli group co-authoring the current PNAS paper. A similar amorphous-to-crystalline transition has since been observed in adult sea urchin spines, in mollusk shells, in zebra fish bones and in tooth enamel. The resulting biominerals are extraordinarily hard and fracture resistant, compared to the minerals of which they are made.

"The amorphous minerals are deposited and they are completely disordered," Gilbert explains. "So the question we addressed is 'how does crystallinity propagate through the amorphous mineral?'"

To answer it, Gilbert and her colleagues observed spicule development in 2- to 3-day-old sea urchin larvae. The sea urchin spicule is formed inside a clump of specialized cells and begins as the animal lays down a single crystal of calcite in the form of a rhombohedral seed, from which the rest of the spicule is formed. Starting from the crystalline center, three arms extend at 120 degrees from each other, as in the hood ornament of a Mercedes-Benz. The three radii are initially amorphous calcium carbonate, but slowly convert to calcite.

"We tried to find evidence of a massive crystal growth, with a well defined growth front, propagating from the central crystal through the amorphous material, but we never observed anything like that," Gilbert says. "What we found, instead, is that 40-100 nanometer amorphous calcium carbonate particles aggregate into the final morphology. One starts converting to crystalline calcite, then another immediately adjacent converts as well, and another, and so on in a three-dimensional domino effect. The pattern of crystallinity, however, is far from straight. It resembles a random walk, or a fractal, like lightning in the sky or water percolating through a porous medium," explains Gilbert.

The new work, according to Gilbert, brings science a key step closer to a thorough understanding of how biominerals form and transform. 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.

The new study was funded by the National Science Foundation and the U.S. Department of Energy.

####

For more information, please click here

Contacts:
Pupa Gilbert

608-262-5829

Copyright © University of Wisconsin-Madison

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Leica Microsystems Presents Universal Hybrid Detector for Single Molecule Detection and Imaging at SfN and ASCB: Leica HyD SMD - the Optimal Detector for Precise and Reliable SMD data November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

Govt.-Legislation/Regulation/Funding/Policy

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Sustainable Nanotechnologies Project November 20th, 2014

Quantum mechanical calculations reveal the hidden states of enzyme active sites November 20th, 2014

NRL Scientists Discover Novel Metamaterial Properties within Hexagonal Boron Nitride November 20th, 2014

Discoveries

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

UO-industry collaboration points to improved nanomaterials: University of Oregon microscope puts spotlight on the surface structure of quantum dots for designing new solar devices November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

Materials/Metamaterials

Sustainable Nanotechnologies Project November 20th, 2014

Total Nanofiber Solutions Company FibeRio® Launches The Fiber Engine® FX Series Systems with 10X Increase in Output November 18th, 2014

Nanocomposites Strengthen Bone Implants November 13th, 2014

Production of Magnetic Nanoparticles with New Structures in Iran November 13th, 2014

Announcements

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Leica Microsystems Presents Universal Hybrid Detector for Single Molecule Detection and Imaging at SfN and ASCB: Leica HyD SMD - the Optimal Detector for Precise and Reliable SMD data November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More












ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE