PNNL

Abstract

Protein scaffolds direct the organization of amorphous precursors that transform into mineralized tissues, but the templating mechanism remains elusive. Motivated by models for biomineralization of tooth enamel, wherein amyloid-like amelogenin nanoribbons guide mineralization of apatite filaments, we investigated the impact of nanoribbon structure and chemistry on amorphous calcium phosphate (ACP) nucleation. Using full-length amelogenin and peptide analogs with an amyloid-like domain, large 2D arrays of nanoribbon were self-assembled on graphite and characterized by in situ atomic force microscopy (AFM) and molecular dynamics simulations. All sequences substantially reduce nucleation barriers by creating low-energy interfaces, while phosphoserines along the length of nanoribbons dramatically enhance kinetic factors associated with ion binding. Furthermore, the simulated distribution of hydrophilic residues at the amyloid-solution interface matches the structure of the multi-ion clusters comprising ACP. These findings show that nanoribbons guide mineralization by generating energetically and sterochemically favorable interfaces for binding apatite precursors.