Periodic fluid shear stress (FSS) is one of the main mechanical microenvironments in mineralization of bone matrix. To elucidate the mechanism of periodic FSS in collagen mineralization, a mechanical loading induced mineralization system is developed and compared with traditional polyacrylic acid (PAA) induced mineralization. Fourier transform infrared (FTIR) spectroscopy, calcium-to-phosphorus molar ratio and transmission electron microscopy (TEM) demonstrate that both periodic FSS and PAA can control the size of amorphous calcium phosphate (ACP) to avoid aggregation and help the formation of intrafibrillar mineralization. Differently, periodic FSS under a proper cycle and range can accelerate the conversion of ACP to apatite crystals and alleviate the reduced transformation caused by PAA. Under the action of template analogues, periodic FSS can also promote the formation of highly oriented hierarchical intrafibrillar mineralized (HIM) collagen. These findings are helpful for understanding the mechanism of collagen mineralization in natural bone matrix and contribute to the design of novel bone substitute materials with hierarchical structures.

中文翻译：

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周期性流体剪切应力诱导的胶原的高度对齐的分级原纤维内矿化。

周期性流体切应力（FSS）是骨基质矿化的主要机械微环境之一。为了阐明胶原蛋白矿化中周期性FSS的机理，开发了一种机械加载诱导的矿化系统，并将其与传统的聚丙烯酸（PAA）诱导的矿化进行了比较。傅里叶变换红外（FTIR）光谱，钙磷摩尔比和透射电子显微镜（TEM）表明，周期性FSS和PAA均可控制无定形磷酸钙（ACP）的大小，以避免聚集并帮助形成纤丝内矿化。不同的是，在适当的周期和范围内进行周期性FSS可以加速ACP向磷灰石晶体的转化，并减轻由PAA引起的相变减少。在模板类似物的作用下，周期性FSS还可以促进高度定向的分层原纤维内矿化（HIM）胶原蛋白的形成。这些发现有助于理解天然骨基质中胶原矿化的机理，并有助于设计具有层次结构的新型骨替代材料。