Metal-Halogen Biomaterials and Wear Resistance

标题：金属-卤素生物材料和耐磨性PI：罗伯特·斯科菲尔德，俄勒冈大学尤金许多节肢动物和其他无脊椎动物的颚、腿爪、刺和其他“工具”含有大量的重金属，如锌和锰，以及卤素，如溴和氯。尽管其浓度达到干质量的25%，但与钙化的人类牙齿不同，无脊椎动物组织并不充满生物矿物质。相反，金属卤素生物材料似乎是一个明显不同的系统，更广泛地应用于小型生物。人们对这些金属卤素生物材料所知甚少，尽管它们在较大生物体内的主要对应物——钙化——被认为是如此重要，以至于它的出现使软体动物和脊椎动物等生物的进化成为可能。在他们之前的nsf资助的项目中，pi发表了第一张富含锌的“工具”的发育和微观结构的综合图片，表明锌在外骨骼发育的很晚才沉积，并且富含锌的组织包含一个独特的管道网络，锌通过它沉积。pi测试了金属卤素组织代表一种独特的生物材料的假设，与生物矿化组织有很大的不同。他们进一步提出，由于近亲生物的金属卤素组织的相似性，这一系统很可能在昆虫和螯合动物进化之前就已经进化得很早了。pi研究表明，在成年早期，随着锌的加入，切叶蚁下颌牙齿的硬度增加了三倍，这表明这种与锌相关的硬度增加是导致年轻人和老年人叶片加工行为差异的原因。在本研究中，将对4个假设进行测试，重点关注两个方面；1) Zn改变机械性能的化学形式和机制，以及2)无脊椎动物与更熟悉的生物矿化组织的机械性能的比较。预计，对于小型生物，金属卤素生物材料将赋予硬度和耐磨性比钙化更有利的平衡。该研究将提高我们对与耐磨性相关的无机生物化学的基本认识，这可能对无脊椎动物的进化、行为和寿命具有重要意义。此外，这项研究可能会导致模仿自然设计的新材料的发展。

Title: Metal-Halogen Biomaterials and Wear resistance PI: Robert Schofield, University of Oregon EugeneThe jaws, leg claws, stings and other "tools" of a many arthropods and other invertebrates, contain extraordinarily high amounts of heavy metals, such as zinc and manganese, and halogens such as bromine and chlorine. Although the concentrations reach 25% of dry mass, unlike calcified human teeth, invertebrate tissue is not filled with the biomineral. Instead, metal-halogen biomaterials appear to be a distinctly different system that is more widely employed among small organisms. Very little is known about these metal-halogen biomaterials, though their main counterpart in larger organisms, calcification, is thought to be of such importance that its advent made possible the evolution of organisms such as mollusks and vertebrates.In their previous NSF-funded project, the PIs published the first comprehensive picture of the development and microscopic structure of Zn-enriched 'tools', showing that Zn was deposited very late in exoskeleton development, and that Zn-rich tissue contained a unique network of canals, through which Zn was deposited. The PIs test the hypothesis that metal-halogen tissues represent a distinct class of biomaterials, differing substantially from biomineralized tissues. Further they suggest that because of similarities in the metal-halogen tissues of distantly related organisms, that this system is likely to have evolved very early, before the evolution of insects and chelicerates. The PIs have shown that the hardness of the mandibular teeth of leaf cutting ants increases by three times as Zn is incorporated during early adult life and suggested that this Zn-correlated hardness increase is responsible for the differences in leaf-processing behavior between young and older adults. In the present study, 4 hypotheses will be tested focusing on two areas; 1) the chemical form and mechanism by which Zn alters mechanical properties, and, 2) a comparison of the mechanical property in invertebrates with more familiar biomineralized tissue. It is expected that, for small organisms, metal-halogen biomaterials will impart a more advantageous balance of hardness and wear resistance than will calcification. This research will improve our basic understanding of inorganic biochemistry related to wear resistance, which may have been important to the evolution, behavior and life span of invertebrates. In addition, this research may lead to the development of new materials that mimic those designed by nature.