Department of Materials Science & Engineering Northwestern University
Evanston, IL, USA
Tuesday October 11, 2022
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.
Abstract: Dental enamel, the hard, wear-resistant covering of human teeth has a hierarchical structure and composition. It is composed of hydroxylapatite crystallites, thousands of which are bundled into rods that are organized in a three-dimensional weave. This architecture 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, iron, carbonate, and fluoride ions. However, imaging the distribution of these minor components in enamel has remained challenging.