Wilmers Jana, Waldron Miranda, Bargmann Swantje
Chair of Solid Mechanics, University of Wuppertal, 42119 Wuppertal, Germany.
Electron Microscope Unit, University of Cape Town, Cape Town 7701, South Africa.
Nanomaterials (Basel). 2021 Apr 9;11(4):969. doi: 10.3390/nano11040969.
Shark tooth enameloid is a hard tissue made up of nanoscale fluorapatite crystallites arranged in a unique hierarchical pattern. This microstructural design results in a macroscopic material that is stiff, strong, and tough, despite consisting almost completely of brittle mineral. In this contribution, we characterize and compare the enameloid microstructure of two modern lamniform sharks, (shortfin mako shark) and (spotted ragged-tooth shark), based on scanning electron microscopy images. The hierarchical microstructure of shark enameloid is discussed in comparison with amniote enamel. Striking similarities in the microstructures of the two hard tissues are found. Identical structural motifs have developed on different levels of the hierarchy in response to similar biomechanical requirements in enameloid and enamel. Analyzing these structural patterns allows the identification of general microstructural design principles and their biomechanical function, thus paving the way for the design of bioinspired composite materials with superior properties such as high strength combined with high fracture resistance.
鲨鱼牙釉质是一种硬组织，由纳米级氟磷灰石微晶以独特的层次模式排列而成。这种微观结构设计使得一种宏观材料尽管几乎完全由脆性矿物组成，但却具有硬度高、强度大且韧性强的特点。在本论文中，我们基于扫描电子显微镜图像对两种现代鼠鲨目鲨鱼（灰鲭鲨和斑皱唇鲨）的牙釉质微观结构进行了表征和比较。将鲨鱼牙釉质的层次微观结构与羊膜动物的牙釉质进行了对比讨论。发现这两种硬组织的微观结构存在显著相似性。由于牙釉质和牙釉质在生物力学方面有相似的需求，相同的结构基元在层次结构的不同层面上得以发展。对这些结构模式进行分析有助于识别一般的微观结构设计原则及其生物力学功能，从而为设计具有高强度与高抗断裂性等优异性能的仿生复合材料铺平道路。
