Conductive polymers have been used for various biomedical applications including biosensors, tissue engineering and regenerative medicine. However, the poor processability and brittleness of these polymers hinder the fabrication of three-dimensional structures with desirable geometries. Moreover, their application in tissue engineering and regenerative medicine has been so far limited to excitable cells such as neurons and muscle cells. To enable their wider adoption in tissue engineering and regenerative medicine, new materials and formulations that overcome current limitations are required. Herein, a biodegradable conductive block copolymer, tetraaniline-b-polycaprolactone-b-tetraaniline (TPT), is synthesised and 3D printed for the first time into porous scaffolds with defined geometries. Inks are formulated by combining TPT with PCL in solutions which are then directly 3D printed to generate porous scaffolds. TPT and PCL are both biodegradable. The combination of TPT with PCL increases the flexibility of the hybrid material compared to pure TPT, which is critical for applications that need mechanical robustness of the scaffolds. The highest TPT content shows the lowest tensile failure strain. Moreover, the absorption of a cell adhesion-promoting protein (fibronectin) and chondrogenic differentiation of chondroprogenitor cells are found to be dependent on the amount of TPT in the blends. Higher content of TPT in the blends increases both fibronectin adsorption and chondrogenic differentiation, though the highest concentration of TPT in the blends is limited by its solubility in the ink. Despite the contradicting effects of TPT concentration on flexibility and chondrogenic differentiation, a concentration that strikes a balance between the two factors is still available. It is worth noting that the effect on chondrogenic differentiation is found in scaffolds without external electric stimulation. Our work demonstrates the possibility of 3D printing flexible conductive and biodegradable scaffolds and their potential use in cartilage tissue regeneration, and opens up future opportunities in using electric stimulation to control chondrogenesis in these scaffolds.

中文翻译：

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三维印刷的可降解导电聚合物支架可促进软骨生成细胞的软骨分化。

导电聚合物已用于各种生物医学应用，包括生物传感器，组织工程学和再生医学。然而，这些聚合物的差的可加工性和脆性阻碍了具有期望的几何形状的三维结构的制造。而且，迄今为止，它们在组织工程和再生医学中的应用仅限于可兴奋的细胞，例如神经元和肌肉细胞。为了使它们在组织工程和再生医学中得到广泛采用，需要克服当前局限性的新材料和配方。本文中，可生物降解的导电嵌段共聚物，四苯胺-b-聚己内酯-b合成了四苯胺（TPT），并首次将其3D打印到具有确定几何形状的多孔支架中。通过在溶液中结合TPT和PCL来配制油墨，然后直接进行3D打印以生成多孔支架。TPT和PCL都是可生物降解的。与纯TPT相比，TPT与PCL的结合提高了混合材料的灵活性，这对于需要脚手架机械坚固性的应用至关重要。TPT含量最高时，拉伸破坏应变最低。而且，发现细胞粘附促进蛋白（纤连蛋白）的吸收和软骨生成细胞的软骨分化取决于混合物中TPT的量。共混物中较高的TPT含量会增加纤连蛋白的吸附和软骨分化，尽管共混物中TPT的最高浓度受其在油墨中的溶解度的限制。尽管TPT浓度对柔韧性和软骨形成分化有相互矛盾的影响，但仍然可以在两个因素之间取得平衡。值得注意的是，在没有外部电刺激的支架中发现了对软骨形成分化的影响。我们的工作证明了3D打印柔性导电和可生物降解支架的可能性及其在软骨组织再生中的潜在用途，并开辟了使用电刺激控制这些支架中软骨形成的未来机会。仍然可以在两个因素之间取得平衡。值得注意的是，在没有外部电刺激的支架中发现了对软骨形成分化的影响。我们的工作证明了3D打印柔性导电和可生物降解支架的可能性及其在软骨组织再生中的潜在用途，并开辟了使用电刺激控制这些支架中软骨形成的未来机会。仍然可以在两个因素之间取得平衡。值得注意的是，在没有外部电刺激的支架中发现了对软骨形成分化的影响。我们的工作证明了3D打印柔性导电和可生物降解支架的可能性及其在软骨组织再生中的潜在用途，并开辟了使用电刺激控制这些支架中软骨形成的未来机会。