学术报告
报告人：美国西北大学材料系DerkJoester教授
报告题目：Chemical Imagingof Interfaces and Interphases
in ToothBiominerals
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top1-2），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 hardestbiological materials. Optimized to withstand the forces of mastication, theyare hierarchically structured, organic/inorganic nanocomposite materials. Forexample, the radulateeth of the chiton are capped with acomposite made from magnetite (Fe3O4) and a nanofibrouschitin scaffold. These teeth are sufficiently hard that the chiton can abraderocks during feeding. Human tooth enamel is composed of hydroxylapatitenanowires, thousands of which are bundled into rods that are organized in athree-dimensional weave; this provides great fracture resistance and a muchenhanced fatigue life. It has long been known that the susceptibility of enamelto caries, i.e. acid corrosion, is greatly dependent on the presence of magnesium,carbonate, and fluoride ions. However, imaging the distribution of theseimpurities in enamel or the organic/inorganic interface in the chiton tooth hasremained challenging.
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Figure 1. Atom probe tomography reconstructions of A: regular mouse enamel; B: pigmented rat enamel; C: multiple grain boundary in mouse enamel; D: amorphous interphase in pigmented rat enamel. |
I will discuss how UV-laser pulsed atomprobe tomography (APT), in combination with correlative imaging andspectroscopy techniques, has given us remarkable new insights into thechemistry of organic/inorganic interfaces, grain boundaries, and amorphousintergranular phases that are integral to the mechanical properties of teethand their resistance to corrosion.1-5Ianticipate that the capabilities and expertise we developed is relevant alsofor 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.,Nature2011,469, 194-197. "Nanoscalechemical tomography of buried organic-inorganic interfaces in the chiton tooth."
[2] Gordon,L. M., Tran, L., Joester, D.,ACS nano2012,6,10667-10675. "Atom probe tomography of apatites and bone-typemineralized tissues."
[3] Gordon,L. M., Román, J. K., Everly, R. M., Cohen, M. J., Wilker, J. J., Joester, D.,AngewChem Int Ed2014,53. "Selective formation ofmetastable ferrihydrite in the chiton tooth."
[4] Gordon,L. M., Cohen, M. J., MacRenaris, K. W., Pasteris, J. D., Seda, T., Joester, D.,Science2015,347, 746-750. "Amorphousintergranular phases control the properties of rodent tooth enamel."
[5] Gordon,L. M., Joester, D.,Frontiers in Physiology2015,6."Mapping residual organics and carbonate at grain boundaries and in theamorphous interphase in mouse incisor enamel."
ShortBiography
DerkJoester is originally from Munich (Bavaria, Germany) and studied Chemistry inTübingen. He travelled to the US on a Fulbright Scholarship to study Chemistryand Biochemistry, and then went on to get his Diploma in Organic Chemistry atETH Zurich, Switzerland, in 1998. He received his Ph.D. for work carried out inorganic, supra-molecular chemistry with Prof. François Diederich at ETH Zurichin 2003, and in the same year became a Postdoctoral Fellow at WeizmannInstitute of Science in the lab of Prof. Lia Addadi in the Department ofStructural Biology. From 2005-2007 he continued his research at the WeizmannInstitute as a Minerva Fellow. In September 2007 he accepted a position at theMaterials Science & Engineering Department at Northwestern University,Evanston, Illinois. In 2013, he was promoted to Associate Professor. Hisresearch interests include biological mechanisms of crystal growth, the role oforganic/inorganic interfaces and confinement in phase transformations,metastable precursor phases, and the structure and propertiesbiomineral-organic composites with hierarchical architectures.
Website:http://joester.mccormick.northwestern.edu/
