BACKGROUND One of the main challenges for extrusion 3D bioprinting is the identification of non-synthetic bioinks with suitable rheological properties and biocompatibility. Our aim was to optimize and compare the printability of crystal, fibril and blend formulations of novel pulp derived nanocellulose bioinks and assess biocompatibility with human nasoseptal chondrocytes. METHODS The printability of crystalline, fibrillated and blend formulations of nanocellulose was determined by assessing resolution (grid-line assay), post-printing shape fidelity and rheology (elasticity, viscosity and shear thinning characteristics) and compared these to pure alginate bioinks. The optimized nanocellulose-alginate bioink was bioprinted with human nasoseptal chondrocytes to determine cytotoxicity, metabolic activity and bioprinted construct topography. RESULTS All nanocellulose-alginate bioink combinations demonstrated a high degree of shear thinning with reversible stress softening behavior which contributed to post-printing shape fidelity. The unique blend of crystal and fibril nanocellulose bioink exhibited nano- as well as micro-roughness for cellular survival and differentiation, as well as maintaining the most stable construct volume in culture. Human nasoseptal chondrocytes demonstrated high metabolic activity post printing and adopted a rounded chondrogenic phenotype after prolonged culture. CONCLUSIONS This study highlights the favorable rheological, swelling and biocompatibility properties of nanocellulose-alginate bioinks for extrusion-based bioprinting.

中文翻译：

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用于挤出 3D 生物打印的纸浆衍生晶体、原纤维和混合纳米纤维素-藻酸盐生物墨水的可打印性。

背景技术 挤出 3D 生物打印的主要挑战之一是识别具有合适流变特性和生物相容性的非合成生物墨水。我们的目标是优化和比较新型纸浆衍生纳米纤维素生物墨水的晶体、原纤维和混合物配方的可印刷性，并评估与人鼻中隔软骨细胞的生物相容性。方法 通过评估分辨率（网格线分析）、打印后形状保真度和流变学（弹性、粘度和剪切稀化特性）来确定纳米纤维素的结晶、原纤化和共混配方的可印刷性，并将这些与纯藻酸盐生物墨水进行比较。优化的纳米纤维素-藻酸盐生物墨水与人鼻中隔软骨细胞进行生物打印，以确定细胞毒性、代谢活性和生物打印的构建体形貌。结果所有纳米纤维素-海藻酸盐生物墨水组合都表现出高度的剪切变薄和可逆的应力软化行为，这有助于打印后的形状保真度。晶体和原纤维纳米纤维素生物墨水的独特混合物表现出细胞存活和分化的纳米和微米粗糙度，并在培养中保持最稳定的构建体积。人鼻中隔软骨细胞在打印后表现出高代谢活性，并在长时间培养后采用圆形软骨形成表型。结论 本研究强调了基于挤出的生物打印的纳米纤维素-藻酸盐生物墨水的良好流变、溶胀和生物相容性。