Extrusion-based 3D printing followed by debinding and sintering is a powerful approach that allows for the fabrication of porous scaffolds from materials (or material combinations) that are otherwise very challenging to process using other additive manufacturing techniques. Iron is one of the materials that have been recently shown to be amenable to processing using this approach. Indeed, a fully interconnected porous design has the potential of resolving the fundamental issue regarding bulk iron, namely a very low rate of biodegradation. However, no extensive evaluation of the biodegradation behavior and properties of porous iron scaffolds made by extrusion-based 3D printing has been reported. Therefore, the in vitro biodegradation behavior, electrochemical response, evolution of mechanical properties along with biodegradation, and responses of an osteoblastic cell line to the 3D printed iron scaffolds were studied. An ink formulation, as well as matching 3D printing, debinding and sintering conditions, was developed to create iron scaffolds with a porosity of 67%, a pore interconnectivity of 96%, and a strut density of 89% after sintering. X-ray diffracometry confirmed the presence of the α-iron phase in the scaffolds without any residuals from the rest of the ink. Owing to the presence of geometrically designed macropores and random micropores in the struts, the in vitro corrosion rate of the scaffolds was much improved as compared to the bulk counterpart, with 7% mass loss after 28 days. The mechanical properties of the scaffolds remained in the range of those of trabecular bone despite 28 days of in vitro biodegradation. The direct culture of MC3T3-E1 preosteoblasts on the scaffolds led to a substantial reduction in living cell count, caused by a high concentration of iron ions, as revealed by the indirect assays. On the other hand, the ability of the cells to spread and form filopodia indicated the cytocompatibility of the corrosion products. Taken together, this study shows the great potential of extrusion-based 3D printed porous iron to be further developed as a biodegradable bone substituting biomaterial.

基于挤压的3D打印，然后进行脱脂和烧结，是一种功能强大的方法，它允许使用材料（或材料组合）制造多孔支架，而使用其他增材制造技术很难加工多孔支架。铁是最近被证明适合使用这种方法进行加工的材料之一。实际上，完全互连的多孔设计具有解决有关大块铁的基本问题的潜力，即非常低的生物降解率。然而，尚未报道对通过基于挤压的3D打印制成的多孔铁支架的生物降解行为和性质进行广泛的评估。因此，体外研究了生物降解行为，电化学响应，机械性能的演变以及生物降解以及成骨细胞系对3D打印铁支架的响应。开发了一种油墨配方以及匹配的3D打印，脱脂和烧结条件，以制造出具有67％的孔隙率，96％的孔互连性和89％的支撑密度的铁支架。X射线衍射法证实了支架中α-铁相的存在，其余油墨没有任何残留。由于支杆中存在几何设计的大孔和随机微孔，因此体外与散装材料相比，脚手架的腐蚀速率大大提高，28天后质量损失为7％。尽管有28天的体外生物降解，支架的机械性能仍保持在小梁骨的范围内。间接测定表明，在支架上直接培养MC3T3-E1成骨细胞可导致活细胞计数的大幅下降，这是由高浓度的铁离子引起的。另一方面，细胞扩散并形成丝状伪足的能力表明了腐蚀产物的细胞相容性。综上所述，这项研究表明基于挤压的3D打印多孔铁具有巨大的潜力，可以进一步发展为可生物降解的骨替代生物材料。