Dental enamel-mimetic large-sized multi-scale ordered architecture built by a well controlled bottom-up strategy

Tooth enamel possesses excellent mechanical properties owing to its multi-scale highly ordered architecture. To develop tooth enamel-mimetic structural materials (EMSMs) is of great significance for understanding the important role of ordered hydroxyapatite (HAP) nanocrystals in tooth enamel and exploring high-performance materials. However, it is still a great challenge to mimic the unique multi-scale ordered architecture of the natural tooth enamel. Herein, inspired by the multi-scale structure and self-assembly of the tooth enamel, we have developed a novel bottom-up step-by-step assembly strategy to build the EMSMs based on ultralong HAP nanowires, and achieved the multi-scale (from nano- to micro- to macro-scale) highly ordered HAP nanowire structure control. In this work, ultralong HAP nanowires are assembled in sequence into highly ordered HAP nanowire bundles, aligned HAP microfibers, and three-dimensional (3-D) highly ordered HAP nanowire bulk, which perfectly imitate the structure and self-assembly of the tooth enamel. This novel method is suitable to fabricate the EMSMs with arbitrary sizes and well-designed shapes, which are promising for various applications in the biomedical fields such as hard tissue defect repair.