In Situ Liquid-Cell TEM Observation of Multiphase Classical and Nonclassical Nucleation of Calcium Oxalate
In Situ Liquid-Cell TEM Observation of Multiphase Classical and Nonclassical Nucleation of Calcium Oxalate
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DOI：
10.1002/adfm.202007736
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发表时间：
2021-02-26
影响因子：
19
通讯作者：
Shahbazian-Yassar, Reza
中科院分区：
文献类型：
--
作者：
Banner, David J.;Firlar, Emre;Shahbazian-Yassar, Reza
草酸钙(CaOx)是肾结石的主要物相，也是植物体内主要的钙储存介质。CaOx可以形成不同晶型、不同水分含量和不同晶体结构的晶体。然而，导致特定CaOx晶体成核的条件和机制尚不清楚。本文采用液胞透射电子显微镜和原子分子动力学模拟方法研究了不同条件下CaO_x的原位成核。结果表明，菱形CaOx一水合物(COM)可以通过经典途径成核，而方形CaOx可以通过非经典多相途径成核。柠檬酸盐是一种肾结石抑制剂，它通过形成钙-柠檬酸盐复合体来增加钙的溶解度，并阻止草酸根离子接近钙。多个水合离子物种的存在将额外的水分子吸引到成核的二水CaOx晶体中。这些发现表明，通过控制成核途径，可以确定CaOx的宏观晶体结构、水化状态和形貌。
Calcium oxalate (CaOx) is the major phase in kidney stones and the primary calcium storage medium in plants. CaOx can form crystals with different lattice types, water contents, and crystal structures. However, the conditions and mechanisms leading to nucleation of particular CaOx crystals are unclear. Here, liquid-cell transmission electron microscopy and atomistic molecular dynamics simulations are used to study in situ CaOx nucleation at different conditions. The observations reveal that rhombohedral CaOx monohydrate (COM) can nucleate via a classical pathway, while square COM can nucleate via a non-classical multiphase pathway. Citrate, a kidney stone inhibitor, increases the solubility of calcium by forming calcium-citrate complexes and blocks oxalate ions from approaching calcium. The presence of multiple hydrated ionic species draws additional water molecules into nucleating CaOx dihydrate crystals. These findings reveal that by controlling the nucleation pathways one can determine the macroscale crystal structure, hydration state, and morphology of CaOx.