Particle-Attachment-Mediated and Matrix/Lattice-Guided Enamel Apatite Crystal Growth

Jacob R. Jokisaari, Canhui Wang, Qiao Qiao, Xuan Hu, David A. Reed, Reiner Bleher, Xianghong Luan, Robert F. Klie, Thomas G.H. Diekwisch*

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Tooth enamel is a hard yet resilient biomaterial that derives its unique mechanical properties from decussating bundles of apatite crystals. To understand enamel crystal nucleation and growth at a nanoscale level and to minimize preparation artifacts, the developing mouse enamel matrix was imaged in situ using graphene liquid cells and atomic resolution scanning transmission electron and cryo-fracture electron microscopy. We report that 1-2 nm diameter mineral precipitates aggregated to form larger 5 nm particle assemblies within ameloblast secretory vesicles or annular organic matrix subunits. Further evidence for the fusion of 1-2 nm mineral precipitates into 5 nm mineral aggregates via particle attachment was provided by matrix-mediated calcium phosphate crystal growth studies. As a next step, aggregated particles organized into rows of 3-10 subunits and developed lattice suprastructures with 0.34 nm gridline spacings corresponding to the (002) planes of apatite crystals. Mineral lattice suprastructures superseded closely matched organic matrix patterns, suggestive of a combination of organic/inorganic templates guiding apatite crystal growth. Upon assembly of 2-5 nm subunits into crystal ribbons, lattice fringes indicative of the presence of larger ordered crystallites were observed surrounding elongating crystal ribbons, presumably guiding the c-axis growth of composite apatite crystals. Cryo-fracture micrographs revealed reticular networks of an organic matrix on the surface of elongating enamel crystal ribbons, suggesting that protein coats facilitate c-axis apatite crystal growth. Together, these data demonstrate (i) the involvement of particle attachment in enamel crystal nucleation, (ii) a combination of matrix- A nd lattice-guided crystal growth, and (iii) fusion of individual crystals via a mechanism similar to Ostwald ripening.

Original languageEnglish (US)
Pages (from-to)3151-3161
Number of pages11
JournalACS nano
Volume13
Issue number3
DOIs
StatePublished - Mar 26 2019

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Keywords

  • apatite
  • atomic scale microscopy
  • crystal growth
  • enamel
  • graphene liquid cell

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Jokisaari, J. R., Wang, C., Qiao, Q., Hu, X., Reed, D. A., Bleher, R., Luan, X., Klie, R. F., & Diekwisch, T. G. H. (2019). Particle-Attachment-Mediated and Matrix/Lattice-Guided Enamel Apatite Crystal Growth. ACS nano, 13(3), 3151-3161. https://doi.org/10.1021/acsnano.8b08668