Our bones and teeth are made up of a complex structure consisting of organic and inorganic materials. The large surface area of these materials in the body creates a critical pathway for the adsorption of beneficial and harmful ions into our bodies. Understanding precisely how these atomic-level impurities are integrated into the structure of bones and teeth, as well as how they affect strength, toughness, and other properties, is key to developing methods to maximize benefits and minimize harm. Atom probe tomography (Atom probe tomography - APT) allows for atomic-scale analysis of these impurities in the surrounding material matrix in 3D form, providing unique insights into the arrangement of atoms.
Chiton is a marine mollusk with some of the hardest teeth among animals because their diet includes rocks. The SEM-EDS map (middle image) reveals a hydroxyapatite core [Ca5(PO4)3(OH)] surrounded by a magnetite [Fe3O4] shell. Further analysis from within the magnetite shell shows a novel structure. Embedded within the magnetite layer are organic nanofibers (organic nanofibers). Many different types of nanofibers coexist, some of which integrate the element Na and others integrate Mg. The complex shape and distribution of these fibers along with organic/inorganic interfaces can be analyzed in 3D through atomic probe tomography to help us understand the biological minerals (biominerals) as well as the origins of their novel properties.
Joester, D., A. C. Hillier, Y. Zhang, and T. J. Prosa (2012), Organic Materials and Organic/Inorganic Heterostructures in Atom Probe Tomography, Microscopy today, May, 26–31.