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Chemical Nanotomography of Ultrahard Tooth Mineral Derk Joester, Northwestern University, DMR 0805313 Chitons, a kind of rock-munching marine mollusk,

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Presentation on theme: "Chemical Nanotomography of Ultrahard Tooth Mineral Derk Joester, Northwestern University, DMR 0805313 Chitons, a kind of rock-munching marine mollusk,"— Presentation transcript:

1 Chemical Nanotomography of Ultrahard Tooth Mineral Derk Joester, Northwestern University, DMR 0805313 Chitons, a kind of rock-munching marine mollusk, have the teeth that are ~4 times harder than ours. The teeth are composed of both nano-crystalline magnetite (Fe 3 O 4 ) and and organic fibers. The resulting composite is not only strong and tough, but also exhibits self-sharpening. Understanding the structure and the chemistry of the fiber-magnetite interface is critical, yet very challenging. L. Gordon and D. Joester, Nature 2011 We have pioneered the use of atom probe tomography (APT), a technique with unrivaled spatial resolution and chemical sensitivity, to investigate this interface. We found that two kinds of nano-scale fibers decorated with either magnesium or sodium ions are present in the tooth. This has implications for the biological design strategy of the Chiton tooth and informs bio- inspired approaches to better materials. Chiton teeth are arranged in rows on the radula. Cross section of a tooth showing outer, ultrahard layer. Very thin organic fibers (3-5 nm, black) inside the magnetite give the tooth give it the necessary toughness to chew on rock. Cross section of fiber showing individual sodium (Na+) ions detected by APT. 200 µm 20 µm

2 Bioengineering Single Crystal Growth Derk Joester, Northwestern University, DMR 0805313 In biology, there are ample examples for sophisticated synthesis and use of materials, in particular the biominerals that make shells, bones and teeth, or gravity and magnetic field receptors. Many hallmarks of biological crystal synthesis, in particular the control of crystal shape, polymorph, and generation of nano-composites are extremely challenging to reproduce in the laboratory. We are biotechnological approaches to grow materials rather than synthesize them. C.-H. Wu, A. Park, and D. Joester, JACS 2011 We have learned that we can control the growth of single crystals of calcium carbonate by engineering PMC cells from the sea urchin embryo (A). We use micro-patterned surfaces with sticky and non-stick patches to control location/orientation of crystals (cf. B and C). In a breakthrough discovery, we have furthermore learned how to switch from linear to branching single crystals using a recombinant growth factor (a protein) from the sea urchin embryo (cf. D and E). We anticipate that this will allow us to grow much more complex structures in the future. A BC DE

3 Bioengineering Single Crystal Growth Derk Joester, Northwestern University, DMR 0805313 UG students in the Discovery Lab reverse-engineer a competitors CdSe quantum dot synthesis. Curriculum Development: Discovery Labs High School Junior Rhiannon Flanagan-Rosario (left) and her mentor Ching-Hsuan Ann Wu working on a Hitachi S4800 HR-FESEM. Engaging Women and Minorities In Science and Engineering Haven Middle School students discover science using our mobile lab. Here, they set up an experiment with live sea urchin embryos. Mobile Lab for K-12 Outreach Janesh Lakhoo, Piotr Maniak, Steve Fitzgerald, Alexander Park, Laura Mueller, Rose Gruenhagen, Fangzheng Quian, Kellen Mobilia, Wisaruth Maethasith, Fei Yin Luk, Lawrence Tran Sea urchin tank farm designed and built by Janesh Lakhoo and Piotr Maniak (BME) Stirrers for sea urchin embryo culture designed / built by Alexander Park (MSE) Undergraduate Participation in Research and Engineering Live cell fluorescence microscopy of PMCs by Kellen Mobilia (CBE) MBP-GFP fusion protein immobilized on amylose beads by Wisaruth Maethasith (MSE)


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