Speaker
Description
Coral reefs cover only 1% of ocean floors, yet they host 25% of all known marine species. This incredible biodiversity is sheltered by the 3D structure of coral skeletons. My group and I revealed that corals form their skeletons by attachment of amorphous calcium carbonate (ACC) nanoparticles[1], then fill interstitial spaces by ion attachment[2]. Polarization-dependent Imaging Contrast mapping (PIC mapping) revealed that subsequent crystallization starts as randomly oriented aragonite (CaCO3) nanocrystals, termed sprinkles, which coarsen and become radially oriented acicular crystals termed spherulites[3-5]. This is Nature’s 3D printing4! The resulting space-filling, solid, isotropic structure grows slowly (0.5-5.0 cm/year) to form m-km coral reefs visible from outer space.
Unexpected nanostructures were revealed by PIC mapping in other completely different biominerals, mollusk shell nacre[6] and human tooth enamel[7]. In both cases the slight misorientation of adjacent nanocrystals plays an important role in toughening the biomineral[5], providing it with better function, and thus providing an evolutionary advantage to the forming animal.
1 T Mass, AJ Giuffre, C-Y Sun, CA Stifler, MJ Frazier, M Neder, N Tamura, CV Stan, MA Marcus, PUPA Gilbert. Amorphous calcium carbonate particles form coral skeletons. Procs Natl Acad Sci 114, E7670-E7678 (2017). DOI: https://doi.org/10.1073/pnas.1707890114
2 C-Y Sun, CA Stifler, RV Chopdekar, CA Schmidt, G Parida, V Schoeppler, BI Fordyce, JH Brau, T Mass, S Tambutté, PUPA Gilbert. From particle attachment to space-filling coral skeletons Procs Natl Acad Sci 117, 30159-30170 (2020). DOI: https://doi.org/10.1073/pnas.2012025117
3 C-Y Sun, L Gránásy, CA Stifler, T Zaquin, RV Chopdekar, N Tamura, JC Weaver, JAY Zhang, S Goffredo, G Falini, MA Marcus, T Pusztai, V Schoeppler, T Mass, PUPA Gilbert. Crystal nucleation and growth of spherulites demonstrated by coral skeletons and phase-field simulations. Acta Biomater 120, 277-292 (2021). DOI: https://doi.org/10.1016/j.actbio.2020.06.027
4 C-Y Sun, MA Marcus, MJ Frazier, AJ Giuffre, T Mass, PU Gilbert. Spherulitic growth of coral skeletons and synthetic aragonite: Nature’s three-dimensional printing. ACS Nano 11, 6612–6622 (2017). DOI: https://pubs.acs.org/doi/10.1021/acsnano.7b00127
5 AJ Lew, CA Stifler, A Tits, CA Schmidt, A Scholl, A Cantamessa, L Müller, Y Delaunois, P Compère, D Ruffoni, MJ Buehler, PUPA Gilbert. A Molecular Scale Understanding of Misorientation Toughening in Corals and Seashells. Adv Mater 35, 2300373 (2023). DOI: https://doi.org/10.1002/adma.202300373
6 PUPA Gilbert, KD Bergmann, CE Myers, MA Marcus, RT DeVol, C-Y Sun, AZ Blonsky, E Tamre, J Zhao, EA Karan, N Tamura, S Lemer, AJ Giuffre, G Giribet, JM Eiler, AH Knoll. Nacre tablet thickness records formation temperature in modern and fossil shells. Earth and Planetary Science Letters 460, 281-292 (2017). DOI: https://doi.org/10.1016/j.epsl.2016.11.012
7 E Beniash, CA Stifler, C-Y Sun, GS Jung, Z Qin, MJ Buehler, PUPA Gilbert. The hidden structure of human enamel Nat Commun 10, 4383/4381-4313 (2019). DOI: https://doi.org/10.1038/s41467-019-12185-7
