Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mother-of-pearl's genesis identified in mineral's transformation

21.10.2015

How nature makes its biominerals -- things like teeth, bone and seashells -- is a playbook scientists have long been trying to read.

Among the most intriguing biominerals is nacre, or mother-of-pearl -- the silky, iridescent, tougher-than-rock composite that lines the shells of some mollusks and coats actual pearls. The material has been worked by humans for millennia to make everything from buttons and tooth implants to architectural tile and inlay for furniture and musical instruments.


The red abalone makes the lustrous but hard-as-nails nacre lining of its shell by changing the atomic structure of amorphous calcium carbonate to produce crystalline aragonite, the mineral that is the basis of nacre. Also known as mother-of-pearl, nacre has been worked by humans for millennia to make jewelry and fancy inlay for furniture and musical instruments.

Credit: Pupa Gilbert

But how nacre is first deposited by the animals that make it has eluded discovery despite decades of scientific inquiry. Now, a team of Wisconsin scientists reports the first direct experimental observations of nacre formation at its earliest stages in a mollusk.

Writing in the Journal of the American Chemical Society, a team led by University of Wisconsin-Madison physics Professor Pupa Gilbert and using the U.S. Department of Energy's Advanced Light Source at the Lawrence Berkeley National Laboratory describes the precursor phases of nacre formation at both the atomic and nanometer scale in red abalone, a marine mollusk with a domed shell lined with mother-of-pearl.

"People have been trying to understand if nacre had an amorphous calcium carbonate precursor for a long time," explains Gilbert, an expert on biomineral formation, referencing the non-crystalline calcium carbonate observed to set the stage for nacre formation. "There is just a tiny amount of amorphous material. It is very hard to catch it before it transforms."

Gilbert and her colleagues, using the synchrotron radiation generated by the Advanced Light Source, employed spectro-microscopy to directly observe the chemical transformation of amorphous calcium carbonate to the mineral aragonite, which manifests itself as nacre by layering microscopic polygonal aragonite tablets like brickwork to underpin the lustrous and durable biomaterial.

"We could only capture it in a handful of pixels, about 20 nanometers in size, at the surface of forming nacre tablets," says Gilbert of the way the mollusk deposits hydrated amorphous calcium carbonate, which rapidly dehydrates and then crystalizes into aragonite.

"Amazing chemistry happens at the surface of forming nacre," says Gilbert, noting that the transformation of amorphous calcium carbonate into crystalline aragonite involves calcium atoms, initially bonded to six oxygen atoms, and ultimately to nine in the crystalline biomineral.

"It is how the atoms are arranged that matters. The actual chemical composition of calcium carbonate does not change. Only the structure does upon crystallization."

That was the big surprise, observes Gilbert: "The change in atomic symmetry around calcium atoms, from six to nine oxygen atoms, surprised us. Everyone expected to find amorphous precursor minerals that already had the symmetry of the final crystal at the atomic scale, lacking only the long-range order of the crystals. We stand corrected."

Gilbert says the new, detailed understanding of how nature makes mother-of-pearl may one day lend itself to industrial application. Highly durable bone implants are one example, and the material is also environmentally friendly.

###

Support for the study by Gilbert and her colleagues was provided by the DOE and the National Science Foundation.

Terry Devitt, (608) 262-8282, trdevitt@wisc.edu

Pupa Gilbert | EurekAlert!

More articles from Materials Sciences:

nachricht Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)

nachricht Successful Mechanical Testing of Nanowires
07.12.2017 | Helmholtz-Zentrum Geesthacht - Zentrum für Material- und Küstenforschung

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

Im Focus: Virtual Reality for Bacteria

An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications

Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...

Im Focus: A space-time sensor for light-matter interactions

Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.

The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Hot vibrating gases under the electron spotlight

12.12.2017 | Life Sciences

New silicon structure opens the gate to quantum computers

12.12.2017 | Information Technology

Using drones to estimate crop damage by wild boars

12.12.2017 | Ecology, The Environment and Conservation

VideoLinks
B2B-VideoLinks
More VideoLinks >>>