Matrix-induced pre-strain and mineralization-dependent interfibrillar shear transfer enable 3D fibrillar deformation in a biogenic armour
Matrix-induced pre-strain and mineralization-dependent interfibrillar shear transfer enable 3D fibrillar deformation in a biogenic armour
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基质诱导的预应变和矿化相关的原纤维间剪切传递使生物装甲中的 3D 原纤维变形成为可能
DOI：
10.1016/j.actbio.2019.09.036
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发表时间：
2019
影响因子：
9.7
通讯作者：
Gupta Himadri S.
中科院分区：
文献类型：
--
作者：
Wang Yanhong;Zhang Yi;Terrill Nicholas J.;Barbieri Ettore;Pugno Nicola M.;Gupta Himadri S.
口足类角质层是一种天然矿化生物材料，由甲壳素、无定形碳酸钙和具有多尺度层次结构的蛋白质组分组成，形成了具有高抗冲击性的保护壳。在超微结构水平上，角质层的机械功能是由纳米尺度的结构实现的，其中甲壳素纤维与包裹的矿物和蛋白质密切相关。然而，这些超微结构构件之间的相互作用，以及它们对所施加的载荷的耦合反应，仍然不清楚。在这里，我们通过同步微束广角X射线衍射结合环境拉伸加载来阐明这些相互作用，以定量天然角质层以及脱矿和脱蛋白后的甲壳素微晶结构，以及宏观加载下甲壳素原纤维应变的时间分辨变化。我们展示了矿物对甲壳素微晶的稳定作用，通过约0.10%的压缩预应变(甲壳素/蛋白质纤维预应力为∼20 Mpa)，在脱矿过程中丢失了甲壳素微晶。基质消化后纤维层硬度的明显降低与蛋白质/基质机械性能的变化有关。此外，脱矿和脱蛋白都改变了纤维网络的三维变形模式，化学修饰引起的非对称角纤维应变与负荷转移纤维间基质的丢失有关。我们的结果证明并量化了纳米尺度上的相互作用(甲壳素-蛋白质和甲壳素-矿物之间的相互作用)在使角质层的分子构象和突出的力学性能方面所起的关键作用，这将为未来的层次化生物启发复合材料的设计提供信息。意义陈述几丁质生物材料(例如节肢动物角质层)在自然界中广泛存在，由于高抗冲击性和轻质引起了人们对生物启发设计的关注。然而，分子构件--α-甲壳素、蛋白质和碳酸钙矿物--的纳米级相互作用如何导致这些材料性能尚不清楚。在这里，我们使用X射线散射来确定在组织负载过程中甲壳素纤维、蛋白质基质和生物矿物质之间的协同作用。我们发现，矿物纳米颗粒稳定了甲壳素微晶结构，蛋白质相预紧了甲壳素纤维，而纤维间基质的化学修饰显著破坏了微纤维甲壳素胶合板网络的2D力学。这些结果将有助于合理设计具有高抗冲击性的先进甲壳素生物材料。
The cuticle of stomatopod is an example of a natural mineralized biomaterial, consisting of chitin, amorphous calcium carbonate and protein components with a multiscale hierarchical structure, and forms a protective shell with high impact resistance. At the ultrastructural level, cuticle mechanical functionality is enabled by the nanoscale architecture, wherein chitin fibrils are in intimate association with enveloping mineral and proteins. However, the interactions between these ultrastructural building blocks, and their coupled response to applied load, remain unclear. Here, we elucidate these interactions via synchrotron microbeam wide-angle X-ray diffraction combined within situtensile loading, to quantify the chitin crystallite structure of native cuticle – and after demineralization and deproteinization – as well as time-resolved changes in chitin fibril strain on macroscopic loading. We demonstrate chitin crystallite stabilization by mineral, seen via a compressive pre-strain of approximately 0.10% (chitin/protein fibre pre-stress of ∼20 MPa), which is lost on demineralization. Clear reductions of stiffness at the fibrillar-level following matrix digestion are linked to the change in the protein/matrix mechanical properties. Furthermore, both demineralization and deproteinization alter the 3D-pattern of deformation of the fibrillar network, with a non-symmetrical angular fibril strain induced by the chemical modifications, associated with loss of the load-transferring interfibrillar matrix. Our results demonstrate and quantify the critical role of interactions at the nanoscale (between chitin-protein and chitin-mineral) in enabling the molecular conformation and outstanding mechanical properties of cuticle, which will inform future design of hierarchical bioinspired composites.Statement of SignificanceChitinous biomaterials (e.g. arthropod cuticle) are widespread in nature and attracting attention for bioinspired design due to high impact resistance coupled with light weight. However, how the nanoscale interactions of the molecular building blocks – alpha-chitin, protein and calcium carbonate mineral – lead to these material properties is not clear. Here we used X-ray scattering to determine the cooperative interactions between chitin fibrils, protein matrix and biominerals, during tissue loading. We find that the chitin crystallite structure is stabilized by mineral nanoparticles, the protein phase prestresses chitin fibrils, and that chemical modification of the interfibrillar matrix significantly disrupts 2D mechanics of the microfibrillar chitin plywood network. These results will aid rational design of advanced chitin-based biomaterials with high impact resistance.