An engineered three-dimensional scaffold with hierarchical porosity and multiple niche microenvironments is produced using a combined multi-nozzle deposition-freeze casting technique. In this paper we present a process to fabricate a scaffold with improved interconnectivity and hierarchical porosity. The scaffold is produced using a two-stage manufacturing process which superimposes a printed porous alginate (Alg) network and a directionally frozen ceramic-polymer matrix. The combination of two processes, multi-nozzle deposition and freeze casting, provides engineering control of the microenvironment of the scaffolds over several length scales; including the addition of lateral porosity and the ratio of polymer to ceramic microstructures. The printed polymer scaffold is submerged in a ceramic-polymer slurry and subsequently, both structures are directionally frozen (freeze cast), superimposing and patterning both microenvironments into a single hierarchical architecture. An optional additional sintering step removes the organic material and densifies the ceramic phase to produce a well-defined network of open pores and a homogenous cell wall material composition. The techniques presented in this contribution address processing challenges, such as structure definition, reproducibility and fine adjustments of unique length scales, which one typically encounters when fabricating topological channels between longitudinal and transverse porous networks.

中文翻译：

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结合多喷嘴沉积和冷冻铸造工艺，叠加两个多孔网络，用于分层三维微环境。

使用组合多喷嘴沉积-冷冻铸造技术生产具有分级孔隙率和多个生态位微环境的工程化三维支架。在本文中，我们提出了一种制造具有改进的互连性和分级孔隙率的支架的工艺。该支架是使用两阶段制造工艺生产的，该工艺将印刷的多孔藻酸盐 (Alg) 网络和定向冷冻的陶瓷聚合物基质叠加在一起。多喷嘴沉积和冷冻铸造两种工艺的结合，提供了对支架微环境在多个长度尺度上的工程控制；包括增加横向孔隙率和聚合物与陶瓷微结构的比例。印刷的聚合物支架浸入陶瓷聚合物浆料中，随后，两种结构都被定向冻结（冷冻铸造），将两种微环境叠加和模式化为一个单一的层次结构。一个可选的额外烧结步骤去除有机材料并使陶瓷相致密，以产生明确的开孔网络和均匀的细胞壁材料组合物。本贡献中介绍的技术解决了处理挑战，例如结构定义、可重复性和独特长度尺度的精细调整，这是在纵向和横向多孔网络之间制造拓扑通道时通常会遇到的问题。一个可选的额外烧结步骤去除有机材料并使陶瓷相致密，以产生明确的开孔网络和均匀的细胞壁材料组合物。本贡献中介绍的技术解决了处理挑战，例如结构定义、可重复性和独特长度尺度的精细调整，这是在纵向和横向多孔网络之间制造拓扑通道时通常会遇到的问题。可选的额外烧结步骤去除有机材料并使陶瓷相致密化，以产生明确的开孔网络和均质的细胞壁材料组合物。本贡献中介绍的技术解决了处理挑战，例如结构定义、可重复性和独特长度尺度的精细调整，这是在纵向和横向多孔网络之间制造拓扑通道时通常会遇到的问题。