Three-dimensional (3D)-printed scaffolds have attracted considerable attention in recent years as they provide a suitable environment for bone cell tissue regeneration and can be customized in shape. Among many other challenges, the material composition and geometric structure have major impacts on the performance of scaffolds. Hydroxyapatite and tricalcium phosphate (HA/TCP), as the major constituents of natural bone and teeth, possess attractive biological properties and are widely used in bone scaffold fabrication. Many fabrication methods have been investigated in attempts to achieve HA/TCP scaffolds with microporous structure enabling cell growth and nutrient transport. However, current 3D printing methods can only achieve the fabrication of HA/TCP scaffolds with certain range of microporous structure. To overcome this challenge, we developed a slurry-based microscale mask image projection stereolithography, allowing us to form a HA/TCP-based photocurable suspension with complex geometry including biomimetic features and hierarchical porosity. Here, the curing performance and physical properties of the HA/TCP suspension were investigated, and a circular movement process for the fabrication of highly viscous HA/TCP suspension was developed. Based on these investigations, the scaffold composition was optimized. We determined that a 30 wt% HA/TCP scaffold with biomimetic hierarchical structure exhibited superior mechanical properties and porosity. Cell proliferation was investigated in vitro, and the surgery was conducted in a nude mouse in vivo model of long bone with cranial neural crest cells and bone marrow mesenchymal stem cells. The results showed our 3D-printed HA/TCP scaffold with biomimetic hierarchical structure is biocompatible and has sufficient mechanical strength for surgery.

中文翻译：

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具有分层多孔结构的羟基磷灰石/磷酸三钙支架的3D打印

三维（3D）打印支架近年来受到了相当大的关注，因为它们为骨细胞组织的再生提供了合适的环境，并且可以定制形状。在许多其他挑战中，材料成分和几何结构对脚手架的性能有重大影响。羟基磷灰石和磷酸三钙（HA / TCP）作为天然骨骼和牙齿的主要成分，具有诱人的生物学特性，被广泛用于骨骼支架的制造中。已经研究了许多制造方法以试图获得具有微孔结构的HA / TCP支架，所述HA / TCP支架能够使细胞生长和营养转运。然而，当前的3D打印方法只能实现具有一定范围的微孔结构的HA / TCP支架的制造。为了克服这一挑战，我们开发了基于浆液的微型掩模图像投影立体光刻技术，使我们能够形成具有复杂几何形状（包括仿生特征和分层孔隙率）的基于HA / TCP的光固化悬浮液。在此，研究了HA / TCP悬浮液的固化性能和物理性能，并开发了用于制造高粘度HA / TCP悬浮液的圆周运动工艺。基于这些研究，对支架的组成进行了优化。我们确定具有仿生分层结构的30 wt％HA / TCP支架表现出优异的机械性能和孔隙率。在体外研究了细胞增殖，并在具有颅神经c细胞和骨髓间充质干细胞的长骨裸鼠体内模型中进行了手术。