Mg²⁺-regulated Directional Assembly of Enamel-like Fluorapatite Nanoarrays Reinforced via Amorphous Intergranular Phases for Accelerated Mineralization

Abstract

The hierarchical architecture of tooth enamel, consisting of aligned hydroxyapatite nanocrystals bonded by Mg²⁺-rich amorphous intergranular phases (AIP), is key to its outstanding mechanical robustness. Replicating this sophisticated structure under mild synthetic conditions remains a formidable challenge. Inspired by the natural biomineralization process, we report a rapid in situ mineralization strategy to fabricate enamel-like fluorapatite nanoarrays regulated by Mg²⁺ (FAP-M) at ambient temperature and pressure. Through Mg²⁺-regulated directional assembly on a preformed hydroxyapatite layer, we achieve epitaxial growth of well-aligned FAP-M nanorods, which are continuously reinforced by a homogeneous Mg²⁺-rich AIP network. This unique architecture results in remarkable mechanical properties, including a hardness of 1.93 ± 0.15 GPa and a Young’s modulus of 75.54 ± 3.85 GPa, attributed to synergistic effects of grain refinement and amorphous phase reinforcement. Furthermore, when applied to demineralized dentin, the FAP-M mineralization system enables rapid surface reconstruction, forming a dense, oriented nanorod layer with restored mechanical properties (hardness: 2.74 ± 0.31 GPa; modulus: 74.91 ± 5.11 GPa). This work not only provides a mild and efficient bioprocessing-inspired pathway to fabricate high-performance enamel-inspired materials under eco-friendly conditions but also demonstrates 啊promising strategy for dentin repair, offering insights into the design of multifunctional structural materials through amorphous-crystalline composite architectures.