Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel.
Chemistry. 2012 Aug 13;18(33):10262-70. doi: 10.1002/chem.201201111. Epub 2012 Jun 13.
Plant cystoliths are mineralized objects that are formed by specialized cells in the leaves of certain plants. The main mineral component of cystoliths by volume is amorphous calcium carbonate (ACC) and the minor component is silica. We show that the silica stalk is formed first and is essential for ACC formation. Furthermore, the cystolith is shown to be composed of four distinct mineral phases with different chemical properties: an almost pure silica phase grades into a Mg-rich silica phase. This Mg-rich silica is overlaid by a relatively stable ACC phase. A bulky and less stable ACC phase encapsulates the first ACC phase. This architecture poses interesting questions about the role of Mg in the silica phase and suggests a strategy for ACC stabilization that takes advantage of a precise regulation of the mineral-growth microenvironment.
植物的晶簇是由某些植物叶片中的特化细胞形成的矿化物体。晶簇的主要矿物成分按体积计为无定形碳酸钙 (ACC)，次要成分是二氧化硅。我们表明，硅质柄首先形成，对于 ACC 的形成是必不可少的。此外，晶簇由具有不同化学性质的四个不同的矿物相组成：几乎纯的二氧化硅相逐渐变为富含镁的二氧化硅相。这种富含镁的二氧化硅覆盖着相对稳定的 ACC 相。一个庞大而不太稳定的 ACC 相包裹着第一个 ACC 相。这种结构对镁在二氧化硅相中的作用提出了有趣的问题，并提出了一种利用对矿物生长微环境的精确调控来稳定 ACC 的策略。
