On the kinetics and dynamics of apatite crystallization at amyloid-solution interfaces found during enamel biomineralization

Mammalian enamel has a remarkable structure made of interwoven apatite filaments. Recent in vivo and in vitro evidence suggests amyloid-like amelogenin nanoribbons act as a scaffold for apatite growth¹. However, the correlation between amyloid structure and apatite crystallization is unclear. Parts of this relationship are unraveled by the kinetics of calcium phosphate nucleation and growth at the amyloid-solution interface through in situ atomic force microscopy. Using peptide analogs of amelogenin, films of oriented nanoribbons with 3-fold symmetry stabilized by Van der Waal’s forces were self-assembled on graphite. They shared similar amyloidal properties even after addition of charged residues at C-terminus or with phosphorylated serine-16. Their role during apatite crystallization was then determined using physiologically-relevant solutions, favorable to heterogenous apatite nucleation. Quantitative analysis reveals that the peptide films, with or without additional charged residues, cannot independently promote apatite nucleation over time, but can provide an interface for growth of nuclei.

1. Carneiro, K. M. M. et al. Amyloid-like ribbons of amelogenins in enamel mineralization. Sci. Rep.6,23105 (2016)