Bioengineering Single Crystal Growth

非技术：该奖项由西北大学材料研究部生物材料项目颁发，旨在研究由方解石（碳酸钙的一种形式）制成的单晶元素针状物的沉积。许多不同的生物，从细菌到人类，都使用复杂的有机/无机复合材料来进行机械支撑（例如骨骼）、喂养（牙釉质）、防御以及对光、重力和磁场的感知。研究人员实验室的工作围绕着开发一种替代材料合成的生物技术，即修改现有的生物系统，而不是在实验室中重新创造它。该研究人员早期的研究表明，原代间充质细胞（PMCs）沉积的针状体的形状和晶体生长方向可以通过重组蛋白血管内皮生长因子（VEGF）来控制。在这些结果的基础上，该团队的目标是增加对PMC培养中晶体生长过程的理解和掌握。为此，将使用复杂的表征技术，如原子探针断层扫描、尖端增强拉曼光谱和x射线显微镜，确定VEGF浓度对针状体结构和组成在纳米到数百微米长度尺度上的影响。使用蛋白质组学和基于特异性抗体的成像技术，将特别关注生物矿物和周围囊泡中蛋白质的分布。蛋白质在成核和生长中的可能功能作用将在体外试验中确定。通过这种方式，研究小组希望了解复杂复合材料的生物调控和加工是如何联系在一起的，本质上是将生物基因组和材料基因组联系在一起。这一知识可以影响从骨移植的程序化合成到大规模二氧化碳封存的广泛领域。研究成果不仅将通过出版物和会议传播给技术受众，而且还将通过整合本科生实验室练习和让本科生作为带薪实验室助理参与研究。最后，团队成员将前往当地学校，使用移动实验室与中学生进行实验。技术：矿化组织是复杂的杂化材料，具有高度的层次结构和在多个长度尺度上对晶体生长的显著控制。尽管近年来生物材料合成取得了很大进展，但许多生物晶体生长的特征尚未在体外重现：多晶控制，弯曲和/或分支单晶，以及有机-无机复合材料的纳米尺度控制。显然，开发一种替代材料合成的生物技术可以大有作为。该研究小组早些时候开发了海胆胚胎原代间质细胞（PMCs）的体外培养系统，以控制方解石（CaCO3）制成的单晶针状体的沉积。先前资助期的一个基本发现是血管内皮生长因子（VEGF）信号控制PMC沉积的针状体的形状和晶体生长方向；这种蛋白质不直接与矿物质相互作用。这提供了一个独特的机会来研究在体外细胞培养系统中生物控制晶体生长的机制。研究小组将在三种不同的长度尺度上进行实验。在亚微米尺度上，研究小组将结合原子探针断层扫描、尖端增强拉曼光谱和x射线显微镜，研究有机-矿物界面在晶体生长中的作用，以及VEGF浓度对针状体微/纳米结构和组成的影响。在亚微米到亚细胞长度的尺度上，研究小组将结合定量蛋白质组学和使用特定抗体成像来阐明针状基质蛋白质的分布。蛋白质在成核和生长中的可能功能作用将在体外试验中确定。最后，在系统尺度上，将确定VEGF信号的时间模式对晶体分支的影响。该研究将影响人们对骨骼元素如何从不同长度尺度的生物过程中产生以及生物过程如何影响晶体生长的理解。这是将发育生物学与物质基因组联系起来的第一步。这一知识可以影响从骨移植的程序化合成到大规模二氧化碳封存的广泛领域。拟议活动的一个重要组成部分是一项教育和外联计划，它补充了研究目标并很好地结合在一起；其要素是在本科课程中传播研究成果和方法，让学生参与研究活动，并利用移动实验室向当地的初中和高中推广。

Non-technical: This award by the Biomaterials program in the Division of Materials Research to Northwestern University is to study the deposition of single crystalline elements, spicules, made from calcite, a form of calcium carbonate. Many different organisms, from bacteria to humans, use sophisticated organic/inorganic composite materials for mechanical support (e.g., bone), feeding (tooth enamel), defense, and sensing of light, gravity, and the magnetic field. Work in the researcher's laboratory revolves around developing a biotechnological alternative to material synthesis, i.e. modifying an existing biological system rather than re-creating it in the laboratory. Earlier studies by this researcher have demonstrated that the shape and crystallographic growth direction of spicules deposited by primary mesenchyme cells (PMCs) could be controlled using a recombinant protein, vascular endothelial growth factor (VEGF). Building on these results, the team aims to increase the understanding of, and mastery over, the crystal growth process in PMC culture. For this purpose, the effect of VEGF concentration on the structure and composition of the spicule at length scales from nanometers to hundreds of microns will be determined, using sophisticated characterization techniques such as atom probe tomography, tip-enhanced Raman spectroscopy, and X-ray microscopy. Special attention will be given to the distribution of proteins in the biomineral and the surrounding vesicle, using a combination of proteomics and specific antibody-based imaging. Possible functional roles of proteins on nucleation and growth will be established in in vitro assays. In this manner, the team hopes to learn how biological regulation and processing of a complex composite material are connected, essentially linking the biological and the materials genome. This knowledge could impact a wide range of areas from programmed synthesis of bone grafts to large-scale carbon dioxide sequestration. Research findings will be disseminated not only to technical audiences through publications and at conferences, but also through integration in undergraduate laboratory exercises and by engaging undergraduate students in the research as paid laboratory assistants. Finally, members of the team will reach out to local schools and perform experiments with high and middle school students using a mobile laboratory.Technical: Mineralized tissues are sophisticated hybrid materials with highly hierarchical architecture and remarkable control over crystal growth at multiple length scales. Despite great recent progress in bio-inspired material synthesis, many of the hallmarks of biological crystal growth have yet to be reproduced in vitro: polymorph control, curving and/or branching single crystals, and nm scale control of organic-inorganic composites. Clearly, much could be gained by developing a biotechnological alternative to materials synthesis. This researcher's team earlier has developed an in vitro culture system of sea urchin embryo primary mesenchyme cells (PMCs) to control the deposition of single crystalline spicules made from calcite (CaCO3). A fundamental discovery of the prior funding period was that vascular endothelial growth factor (VEGF) signaling controls the shape and crystallographic growth direction of spicules deposited by PMC; the protein does so without directly interacting with the mineral. This provides the unique opportunity to investigate the mechanism underlying this remarkable example of biological control over crystal growth in a well-characterized in vitro cell culture system. The team will do so at three different length scales. At the sub-micron scale, the team will investigate, using a combination of atom probe tomography, tip-enhanced Raman spectroscopy, and X-ray microscopy, the role of organic-mineral interfaces in crystal growth and the impact of the VEGF concentration on the micro/nanostructure and composition of spicules. At the submicron to subcellular length scales, the team will use a combination of quantitative proteomics and imaging using specific antibodies to elucidate the distribution of spicule matrix proteins. Possible functional roles of proteins on nucleation and growth will be established in in vitro assays. Finally, at the system scale, the impact of temporal patterns of VEGF signaling on the crystal branching will be determined. The proposed research will impact the understanding how skeletal elements arise from biological processes at different length scales and how biological processing affects crystal growth. This is a first step to connect developmental biology to the materials genome. This knowledge could impact a wide range of areas from programmed synthesis of bone grafts to large-scale carbon dioxide sequestration. An important component of the proposed activity is an education and outreach-plan that complements the research objectives and is well integrated; its elements are dissemination of research results and methods in the undergraduate curriculum, engagement of students in the research activities, and outreach to local middle and high schools using a mobile laboratory.