Gout is a kind of severe joint disease caused by monosodium urate monohydrate (MSUM) deposition in the synovial fluid. Numerous studies have focused on the influences of the components in synovial fluid on the nucleation of MSUM in solution. Yet little is known about the pathological pathway of MSUM crystallization in vivo. Herein, the pathological crystallization pathway of MSUM was investigated in a simulated biological environment (0.15 M Na⁺ and pH 7.40 buffer). Optical and electron microscope images in combination with powder X-ray diffraction demonstrated that the formation of MSUM involves three stages of molecular aggregation to form fibril-like amorphous subunits, the agglomeration of these nanosized subunits, and the phase transition from amorphous to filamentous crystals. Further, Fourier transform infrared spectroscopy and Raman spectra show that the filamentous crystals bear a structure extremely similar to that of amorphous agglomerates. However, the amorphous form contains more water content in comparison to that of MSUM crystals, as unveiled by thermal analyses. The time-resolved dynamic light scattering and small-angle X-ray scattering data reveal the formation of fibril-like nanoprecursors in the early stage of nucleation and the structure evolution over time. Thus, a nonclassical crystallization mechanism for MSUM in a simulated joint environment was proposed.

中文翻译：

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了解仿生基质中一水合尿酸钠的结晶途径

痛风是一种由滑液中尿酸一钠（MSUM）沉积引起的严重关节疾病。许多研究集中在滑液中的成分对溶液中MSUM成核的影响。关于体内MSUM结晶的病理途径还知之甚少。本文在模拟的生物环境（0.15 M Na ⁺和pH 7.40缓冲液）。光学和电子显微镜图像结合粉末X射线衍射表明，MSUM的形成涉及三个阶段的分子聚集，以形成原纤维状的非晶亚基，这些纳米级亚基的团聚以及从非晶态到丝状晶体的相变。此外，傅立叶变换红外光谱和拉曼光谱表明，丝状晶体具有与非晶团聚物极其相似的结构。但是，热分析表明，与MSUM晶体相比，无定形形式的水分含量更高。时间分辨的动态光散射和小角度X射线散射数据揭示了成核初期纤维状纳米前体的形成以及结构随时间的演变。从而，