学术报告
报告人：美国西北大学材料系Derk Joester教授
报告题目：Chemical Imaging of Interfaces and Interphases
in Tooth Biominerals
地点：国际交叉研究院IRC楼308室
时间：2017年3月3日，15：00
联系人：赵立东
Joester教授主要的研究兴趣包括：晶体生长的生物机制、有机/无机材料界面、相变、亚稳相、具有分层架构生物有机复合材料的结构和性能等。鉴于北航材料学院在国际上的显著影响，Joester教授此次来北航还有另一个目的，为美国西北大学材料系寻找优秀的博士生生源。他将在此次报告中介绍西北大学材料系（全美排名top 1-2），有感兴趣的学生可以到现场与他交流。
Chemical Imaging of Interfaces and Interphases
in Tooth Biominerals
Derk Joester
Materials Science and Engineering, Northwestern University, d-joester@northwestern.edu.
Tooth biominerals are among the hardest biological materials. Optimized to withstand the forces of mastication, they are hierarchically structured, organic/inorganic nanocomposite materials. For example, the radula teeth of the chiton are capped with a composite made from magnetite (Fe3O4) and a nanofibrous chitin scaffold. These teeth are sufficiently hard that the chiton can abrade rocks during feeding. Human tooth enamel is composed of hydroxylapatite nanowires, thousands of which are bundled into rods that are organized in a three-dimensional weave; this provides great fracture resistance and a much enhanced fatigue life. It has long been known that the susceptibility of enamel to caries, i.e. acid corrosion, is greatly dependent on the presence of magnesium, carbonate, and fluoride ions. However, imaging the distribution of these impurities in enamel or the organic/inorganic interface in the chiton tooth has remained challenging.
I will discuss how UV-laser pulsed atom probe tomography (APT), in combination with correlative imaging and spectroscopy techniques, has given us remarkable new insights into the chemistry of organic/inorganic interfaces, grain boundaries, and amorphous intergranular phases that are integral to the mechanical properties of teeth and their resistance to corrosion.1-5 I anticipate that the capabilities and expertise we developed is relevant also for organic/inorganic materials in the fields of biomaterials, energy materials, and electronic materials and will discuss some of our forays into these areas.
[1] Gordon, L. M., Joester, D., Nature 2011, 469, 194-197. "Nanoscale chemical tomography of buried organic-inorganic interfaces in the chiton tooth."
[2] Gordon, L. M., Tran, L., Joester, D., ACS nano 2012, 6, 10667-10675. "Atom probe tomography of apatites and bone-type mineralized tissues."
[3] Gordon, L. M., Román, J. K., Everly, R. M., Cohen, M. J., Wilker, J. J., Joester, D., Angew Chem Int Ed 2014, 53. "Selective formation of metastable ferrihydrite in the chiton tooth."
[4] Gordon, L. M., Cohen, M. J., MacRenaris, K. W., Pasteris, J. D., Seda, T., Joester, D., Science 2015, 347, 746-750. "Amorphous intergranular phases control the properties of rodent tooth enamel."
[5] Gordon, L. M., Joester, D., Frontiers in Physiology 2015, 6. "Mapping residual organics and carbonate at grain boundaries and in the amorphous interphase in mouse incisor enamel."
Short Biography
Derk Joester is originally from Munich (Bavaria, Germany) and studied Chemistry in Tübingen. He travelled to the US on a Fulbright Scholarship to study Chemistry and Biochemistry, and then went on to get his Diploma in Organic Chemistry at ETH Zurich, Switzerland, in 1998. He received his Ph.D. for work carried out in organic, supra-molecular chemistry with Prof. François Diederich at ETH Zurich in 2003, and in the same year became a Postdoctoral Fellow at Weizmann Institute of Science in the lab of Prof. Lia Addadi in the Department of Structural Biology. From 2005-2007 he continued his research at the Weizmann Institute as a Minerva Fellow. In September 2007 he accepted a position at the Materials Science & Engineering Department at Northwestern University, Evanston, Illinois. In 2013, he was promoted to Associate Professor. His research interests include biological mechanisms of crystal growth, the role of organic/inorganic interfaces and confinement in phase transformations, metastable precursor phases, and the structure and properties biomineral-organic composites with hierarchical architectures.
Website: http://joester.mccormick.northwestern.edu/
