Understanding Biocrystallization in Dinoflagellates: From Biological Pathways to Functionalized Hybrid Materials

5亿年来，藻类通过沉淀矿物质来固定二氧化碳，从而塑造了我们的环境。这种生物矿化作用产生了各种具有壮观形态的复杂结构。生物系统中规则性的一个范例是由碳酸钙制成的单细胞甲藻的高度有序的多孔外壳。它们的长程形态规律性是目前技术所无法达到的。在过去的几十年中，在理解硅藻或颗石藻等模式生物中生物矿物形成的关键生化机制方面取得了重大进展。相比之下，控制腰鞭毛虫复杂矿物结构的机制实际上是未知的。这是非常令人惊讶的，因为结构形成不是发生在细胞内的沉积囊泡中，而是发生在控制较少的细胞外空间，即所谓的外部基质中。这使得甲藻是一个非常适合的模型系统，特别是在仿生材料合成方面。在我的PostDoc小组Lia Addadi和Steve Weiner（Weizmann-Institute of Science）中，我们开发了一个新的甲藻生物矿化模型。它包括积极吸收的Ca 2+，在MgCaP-前体体的临时沉积，挤出到外部基质和转化成低镁方解石。然而，结构形态发生的许多细节仍然不清楚。因此，该项目集中在以下问题：（A）我们可以从生物矿物组成中推断出关于结构形态发生的什么？(B)哪些有机成分形成外部基质，它们如何影响晶体成核和生长？(C)镁和磷与钙的积累、储存和运输有什么关系？(D)前体相的确切化学成分是什么-涉及无定形前体吗？我们提出了一种独特的光谱技术（ICP-OES，振动光谱，NMR，质谱，包括质谱）的组合。纳米SIMS）与先进的生物成像（体内荧光，低温电子显微镜，FIB-SEM-EBSD）作为最有前途的方法。结合选择性同位素脉冲标记NMR/拉曼成像方法将允许观察体内钙化过程中的细胞内变化。此外，我们希望探索基于甲藻的生物材料，提出以下问题：（E）我们能否保持甲藻衍生材料的结构完整性以供应用？(F)我们如何将多孔结构功能化或转化为不同的应用？介孔结构是一类越来越重要的材料，在许多技术领域具有重要意义。生物衍生的介孔系统由于其生物相容性而更加引人注目。因此，该项目旨在将结构形成的生物学基础与材料应用联合收割机结合起来。

For 500 million years algae have shaped our environment by fixing CO2 through the precipitation of minerals. This biomineralization gives rise to a variety of complex architectures with spectacular morphologies. A paradigm example of regularity in biological systems are the highly ordered, porous shells of unicellular dinoflagellates made of calcium carbonate. Their long-range morphological regularity is beyond the reach of current technology. During the last decades, significant progress has been made in understanding the key biochemical mechanisms responsible for biomineral formation in model organisms like diatoms or coccolithophores. In contrast, the mechanisms that control the intricate mineral construction in dinoflagellates are practically unknown. This is very surprising, because structure formation does not take place in an intracellular, deposition vesicle, but instead in a less controlled, extracellular space, the so-called outer matrix. This makes dinoflagellates a well-suited model system especially in view of biomimetic materials synthesis.During my PostDoc in the group Lia Addadi and Steve Weiner (Weizmann-Institute of Science), we developed a new dinoflagellate biomineralization model. It includes the active uptake of Ca2+, a temporary deposition in MgCaP-precursor bodies, extrusion into the outer matrix and transformation into low Mg-calcite. However, many details of structure morphogenesis are still not understood. Therefore, the project focusses on the following questions:(A) What can we deduce from the biomineral composition about structure morphogenesis?(B) Which organic constituents are forming the outer matrix and how do they influence crystal nucleation and growth?(C) What is the relevance of magnesium and phosphorus for Ca-accumulation, storage and transport? (D) What is the exact chemical composition of the precursor phase – is an amorphous precursor involved?We propose a unique combination of spectroscopic techniques (ICP-OES, vibrational spectroscopy, NMR, mass spectrometry incl. nano-SIMS) with advanced bioimaging (in vivo-fluorescence, cryo electron microscopy, FIB-SEM-EBSD) as a most promising approach. A combined selective isotope-pulse labeling NMR/Raman imaging-approach will allow to observe intracellular changes during calcification in vivo. In addition, we want to explore dinoflagellate-based biomaterials, asking the following questions: (E) Can we preserve the structural integrity of dinoflagellate-derived materials for applications? (F) How can we functionalize or converted the porous structures for different applications? Mesoporous structures are an increasingly important class of materials with high significance in many technological domains. Bio-derived mesoporous systems are even more compelling because of their biocompatibility. For this reason, the project aims to combine the biological fundamentals of structure formation with materials applications.