Spatiotemporal Regulation of Hierarchical Assembly of Hydroxyapatite for Enamel Remineralization

Abstract

ABSTRACT The hierarchical structure of tooth enamel confers exceptional mechanical robustness, yet its biomimetic regeneration remains a significant challenge. We develop an enzymatic mineralization system (EMS) that achieves enamel regeneration by directing the hierarchical assembly of hydroxyapatite (HAP). Within the EMS, the alkaline phosphatase hydrolyzes β‐glycerophosphate (β‐GP), triggering the mineralization reaction of calcium phosphate (CaP) and controlling its structural evolution. The mineralization process is characterized by a series of spatiotemporal events, in which CaP prenucleation clusters initially form and transform into HAP nanorod building blocks; these units then hierarchically self‐assemble into microscale crystalline bundles that resemble native enamel rods. Mechanistically, differential adsorption of β‐GP on the (100) and (002) facets of HAP, together with facet‐dependent enzymatic cleavage of surface‐bound β‐GP, generates high‐energy facets and interfacial energy differences that drive the hierarchical assembly, beginning with c ‐axis–oriented attachment followed by lateral aggregation. Extending this new strategy to enamel remineralization, the EMS restores the native microstructure and essential mechanical properties. Moreover, a hydrogel‐based EMS demonstrates clinical translatability through effective in vivo repair. This paradigm of interfacial energy–modulated assembly provides a robust blueprint for the bottom‐up construction of complex, high‐performance biomimetic materials.