Teeth and bone are important and complex structures in humans and other animals, but little is actually known about their chemical structure at the atomic scale. What exactly gives them their renowned toughness, hardness and strength? How do organisms control the synthesis of these advanced functional composites?
Now, using a highly sophisticated atomic-scale imaging tool on a sea creature's tooth, two Northwestern University researchers have peeled away some of the mystery of organic/inorganic interfaces that are at the heart of tooth and bone structure. They are the first to produce a three-dimensional map of the location and identity of millions of individual atoms in the complex hybrid material that allows the animal to literally chew rock.
Demonstrating that atom-probe tomography (APT) can be used to interrogate such materials opens up the possibility of tracking fluoride in teeth and cancer and osteoporosis drugs in bone (at previously inaccessible length scales). The detailed knowledge of organic/inorganic interfaces also will help scientists rationally design useful new materials -- flexible electronics, polymers and nanocomposite materials, such as organic photovoltaics -- that combine the best properties of organic and inorganic materials.
The results will be published Jan. 13 by the journal Nature.
"The interface between the organic and inorganic materials plays a large role in controlling properties and structure," said Derk Joester, senior author of the paper. "How do organisms make and control these materials? We need to understand this architecture on the nanoscale level to design new materials intelligently. Otherwise we really have no idea what is going on."
Joester is the Morris E. Fine Junior Professor in Materials and Manufacturing at the McCormick School of Engineering and Applied Science. Lyle Gordon, a doctoral student in Joester's lab, is the other author of the paper.
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