The unique properties in tooth enamel result from dynamic interactions between proteins with calcium phosphate phases at different stages. At the onset of mineralization, proteins such as amelogenin adsorb onto amorphous calcium phosphate (ACP) nanoparticles (NP), promoting their aggregation and transformation to hydroxyapatite (HAP), one of the hardest biomaterials. The protein is removed in later stages by enzymatic degradation during normal enamel formation. Obstructions in these processes however can lead to weakened enamel and malformed teeth, a condition known as amelogenesis imperfecta (AI). These protein-mineral interactions are critical to mineralization but remain poorly understood due to technical limitations in visualizing protein distributions associated with NP. Here, for the first time, three-dimensional atom probe tomography (3D APT) was utilized to resolve the protein distribution in an amelogenin-mineralized HAP NP system <i>in vitro</i>. Systematic analyses were also conducted on defined interfaces, i.e., HAP microparticles with and without amelogenin adsorbed to its surfaces, to develop specimen preparation and analytical techniques for characterizing complex protein-mineral NP interfaces with APT. Amelogenin is found to be heterogeneously and nonrandomly distributed across HAP particulates. The protein can also become entrapped between NP, potentially alludes to mechanisms influencing AI. This study demonstrates APT’s unique capability to resolve chemical distributions in 3D, which can be broadly applied to understand the role of organics in crystal aggregation and the potential mineralization mechanisms during early stages of enamel formation.

Analysis of complex protein-mineral interfaces enabled by three dimensional atom probe tomography

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.