Abstract:
Mineralized tissues are paradigmatic hierarchical materials that reap synergy from structural and compositional gradients at multiple length scales in ways that are challenging to reproduce by conventional means. My laboratory studies the formation, functional properties, and degradation of mineralized tissues. We use model systems ranging from single crystalline endoskeletal elements deposited by single cells to the formation of dental tissues that comprise nanocrystalline and amorphous minerals deposited in complex organic matrices. Applications include the development of bio-inspired materials, sequestration of 90 Sr from nuclear waste, and improving prophylaxis and minimally invasive intervention in dental care.
Herein, I will focus on dental tissues that are optimized to withstand the forces of mastication and the challenging chemical environment of the oral cavity. Human dental enamel is composed of hydroxylapatite (Ca 5 (PO 4 ) 3 OH) nanocrystallites, 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 but leaves our teeth vulnerable to erosive tooth wear and tooth decay (caries). I will discuss how chemical imaging using UV-laser pulsed atom probe tomography (APT), electron microscopy, and synchrotron X-ray techniques has provided deep new insights into the chemistry of nanoscale organic/inorganic interfaces, presence of amorphous intergranular phases, and complex dopant gradients that are integral to properties of teeth and their resistance to corrosion.[1-5] I will further report on development of correlative elemental imaging using X-ray diffraction at the mesoscale (here: 0.25-20 µm) that allows us to extend the field of view beyond what APT can deliver.[6] Finally, I will provide an update on our investigation of diffusive transport processes in enamel using APT and ToF-SIMS, and discuss my vision for integrating this information to enable predictive modeling of enamel dissolution.
[1] Gordon and Joester, Nature 2011, 469, 194-197. [2] Gordon, Tran, and Joester, ACS nano 2012, 6, 10667-10675. [3] Gordon, Cohen, MacRenaris, Pasteris, Seda, and Joester, Science 2015, 347, 746-750. [4] Gordon, Joester, Front Physiol 2015, 6. [5] DeRocher, Smeets, Goodge, Zachman, Balachandran, Stegbauer, Cohen, Gordon, Rondinelli, Kourkoutis, Joester, D. Nature 2020, 583, 66-71. [6] Free, DeRocher, Cooley, Xu, Stock, and Joester, Proc Natl Acad Sci USA 2022, 119, e2211285119.
This work was in part supported by: NIH-NIDCR R03 DE025303-01 and R01 DE025702-01; NSF DMR-1508399 and DMR-1539918; and DOE DE-AC02-06CH11357.
Speaker profile:
Derk Joester is originally from Munich (Bavaria, Germany) and studied Chemistry in Tübingen. He first came 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, where he currently is a 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 of mineralized tissues with hierarchical architectures. His lab pioneered the application of atom probe tomography to biomineralized tissues and has contributed to the fundamental understanding of structure and composition of dental enamel.