A ZINC-HISTIDINE, IRON PHOSPHATE, AND ZINC HYDROXIDE BIO-COMPOSITE IN CUTTING AND PUNCTURING TOOLS

切割和穿刺工具中的组氨酸锌、磷酸铁和氢氧化锌生物复合材料

• 批准号: 2104177
• 负责人: Robert Schofield
• 金额: $ 55万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104177&HistoricalAwards=false
• 关键词: ZINC; HISTIDINE; IRON; PHOSPHATE; HYDROXIDE

Non-technical summaryHow do small animals like ants and scorpions so easily puncture human skin, while humans would have a difficult time biting through similar skin, even with their vastly stronger jaw muscles? The answer is that organisms with small muscles focus their tiny forces using very sharp mouth parts, stings and claws. But, sharp tools are easily damaged, and if an organism is not strong enough to cut with blunted tools, damage and wear may be fatal. Because of this pressure, special materials may have evolved to help small organisms make sharp tools and keep them sharp. Humans may learn from these materials, and use this knowledge to improve human-made materials. A good candidate for such a material was recently discovered in scorpion mouth claws. This material may minimize and even “heal” damage and wear of the cutting edges. This grant will confirm and further study the composition of this scorpion material by disassembling the material nearly atom-by-atom using Atom Probe Tomography. The material is thought to contain two different minerals, iron phosphate, and zinc hydroxide, as well as a protein component that contains about 10% zinc. The hardness and other mechanical properties of the new material will be investigated using techniques that can measure these properties for tiny samples. In addition, the behavior of the sharp edges during cutting will be studied using a testing device that is integrated into an electron microscope and cuts and punctures with the claws. The scorpion material is strengthened by zinc-histidine cross links, which act like cross beams strengthening a building, but these cross links are sometimes broken under the pressures of cutting. One possible reason for the large quantities of extra zinc is to quickly repair broken zinc-histidine cross links. In addition, the zinc hydroxide may fill in and bond opposite sides of developing cracks. The electron microscope will allow visualization of wear, damage and self-healing during cutting, and the testing machine will measure the forces required for repeated puncture. The scorpion material will be compared to other materials like human-made blades and tips, and the researchers will investigate how the scorpions make the material by examining scorpions at various stages of development. In addition to potential contributions to materials technology and materials science, this project will further the understanding of the importance of materials in biology, bridging the fields of material science and organismal biology. A graduate student and dozens of undergraduates will also receive research training through this project.Technical summarySmall animals often overcome force limitations using very sharp mouth parts, stings and claws. But, sharp tools are easily damaged, and if an organism relies on sharp tools for defense or food acquisition, damage and wear may be fatal. The project will investigate a recently discovered complex biomaterial in scorpion mouth claws that may have evolved to produce sharp structures while minimizing and possibly “healing” damage and wear. Atom Probe Tomography will be used to confirm and extend the preliminary findings, which suggested that the material contains two different biominerals, iron phosphate, and zinc hydroxide, as well as a histidine - rich protein that binds Zn in ~10% concentrations. Nanoindentation will be used to measure hardness, modulus of elasticity and damping (loss tangent), and a puncture/cutting tester will be installed inside a Scanning Electron Microscope in order to visualize how the material wears during the puncture/cutting process, and whether the claw tips and edges have self-healing properties. The self-healing hypothesis is that broken zinc-histidine bonds re-establish in a manner similar to the minute-scale healing of zinc-histidine bonds recently discovered in mussel byssal threads. The rate of repeated punctures in the puncture testing machine, and repeated indentations with the nanoindenter, will be varied in order to investigate self-healing. One possible explanation for the presence of zinc hydroxide is that it acts as a ready supply of zinc for this self-healing mechanism, helping bonds re-establish quickly. A cyclical breaking and re-establishing of many zinc-histidine bonds could act as a damping mechanism, absorbing energy that might otherwise be available for fracture. Finally, scorpions will be examined at various stages of development in order to begin to understand how they produce this complex material. In addition to the potential of inspiring new materials technology and materials science, this project will further the understanding of the importance of materials in biology, bridging the fields of materials science and organismal biology by translating material property differences into differences in required force and muscle mass. A graduate student and dozens of undergraduates will also receive research training through this project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术性总结蚂蚁和蝎子这样的小动物是如何如此容易地刺穿人类皮肤的，而人类却很难咬穿类似的皮肤，即使他们的下巴肌肉非常强壮？答案是，有着小肌肉的生物利用非常锋利的口器、刺和爪来集中它们微小的力量。但是，锋利的工具很容易损坏，如果生物体不够强壮，无法用钝的工具切割，损坏和磨损可能是致命的。由于这种压力，特殊的材料可能已经进化，以帮助小生物制造锋利的工具并保持锋利。人类可以从这些材料中学习，并利用这些知识来改进人造材料。最近在蝎子嘴爪中发现了这种材料的一个很好的候选者。这种材料可以最小化甚至“愈合”切割边缘的损坏和磨损。这项资助将通过使用原子探针断层扫描技术几乎一个原子一个原子地分解材料来确认和进一步研究这种蝎子材料的组成。这种材料被认为含有两种不同的矿物质，磷酸铁和氢氧化锌，以及含有约10%锌的蛋白质成分。将使用可以测量微小样本的硬度和其他机械性能的技术来研究新材料的硬度和其他机械性能。 此外，将使用集成到电子显微镜中的测试装置研究切割过程中锋利边缘的行为，并使用爪进行切割和穿刺。蝎子的材料是由锌-组氨酸交联加强的，就像加固建筑物的横梁一样，但这些交联有时会在切割的压力下断裂。大量额外锌的一个可能原因是快速修复断裂的锌-组氨酸交联。此外，氢氧化锌可以填充并结合发展中裂纹的相对侧。电子显微镜将允许观察切割过程中的磨损、损坏和自愈，试验机将测量重复穿刺所需的力。蝎子材料将与人造刀片和尖端等其他材料进行比较，研究人员将通过检查处于不同发育阶段的蝎子来研究蝎子如何制造材料。 除了对材料技术和材料科学的潜在贡献外，该项目还将进一步了解材料在生物学中的重要性，弥合材料科学和生物学领域。一名研究生和几十名本科生也将通过这个项目接受研究培训。技术总结小动物经常使用非常锋利的口器、刺和爪子来克服力量的限制。但是，锋利的工具很容易损坏，如果生物体依赖锋利的工具进行防御或获取食物，损坏和磨损可能是致命的。该项目将研究最近在蝎子嘴爪中发现的一种复杂生物材料，这种材料可能已经进化到产生锋利的结构，同时最大限度地减少并可能“治愈”损伤和磨损。原子探针断层扫描将用于确认和扩展初步发现，初步发现表明该材料含有两种不同的生物矿物，磷酸铁和氢氧化锌，以及富含组氨酸的蛋白质，其结合浓度约为10%的锌。纳米压痕将用于测量硬度、弹性模量和阻尼（损耗角正切），穿刺/切割测试仪将安装在扫描电子显微镜内，以观察材料在穿刺/切割过程中的磨损情况，以及爪尖和边缘是否具有自修复特性。自我修复的假说是，断裂的锌-组氨酸键重新建立的方式类似于最近在贻贝深海线程中发现的锌-组氨酸键的分钟级愈合。将改变穿刺试验机中的重复穿刺率和纳米压痕仪的重复压痕率，以研究自愈合。氢氧化锌的存在的一个可能的解释是，它作为一个现成的锌供应这种自我修复机制，帮助债券迅速重建。许多锌-组氨酸键的周期性断裂和重建可以作为阻尼机制，吸收可能用于断裂的能量。最后，蝎子将在不同的发展阶段进行检查，以便开始了解他们如何产生这种复杂的材料。除了激发新材料技术和材料科学的潜力外，该项目还将进一步了解材料在生物学中的重要性，通过将材料特性差异转化为所需力量和肌肉质量的差异，弥合材料科学和生物体生物学领域。一名研究生和数十名本科生也将通过该项目接受研究培训。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。