To achieve three-dimensional (3D) microenvironment for complex tissue regeneration is a great challenge in developing biomaterials as artificial extracellular matrix (ECM) with properties similar to that of native tissue. In this case, polysaccharide-based hydrogel shows the great potential as ECM in the regeneration of damaged tissues or reconstruction of the organ by demonstrating their properties similar to native ECM. Extrusion 3D printing of only cell-free or cell-loaded hydrogel-ink has been more sophisticated in fabricating desired compositions and architectures for tissue engineering applications. The development of stable cell-free and cell-loaded hydrogel-inks with optimal physicochemical properties and biocompatibility is also a major concern in direct-write extrusion-based 3D printing. In this study, carboxylated-cellulose nanocrystals (cCNCs) were prepared by using ammonium persulfate (APS), where TEM, FTIR and XRD analyses confirmed the successful preparation of cCNCs. Further, the effect of cCNCs (-COOH) and/or xanthan gum (XG) (-COOH) was evaluated on the rheological behavior of the sodium alginate (SA) hydrogel matrix. The incorporation of cCNCs and XG manipulated the flow and shear-thinning behavior of the hydrogel-inks, thereby improving the printing ability. The results showed good rheological properties, post-printing fidelity, and dynamic mechanical properties under compression of the developed hydrogel-inks. Furthermore, good viability of the human skin fibroblast (CCD-986Sk) cells on bulk hydrogels (hydrogel-inks) was observed, as demonstrated by both qualitative and quantitative cell analyses. The use of cCNCs and XG in SA hydrogel-inks provides primarily insight for further improvement in designing 3D bioprintable hydrogel-inks.

中文翻译：

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用于组织工程的3D可打印的羧化纤维素纳米晶体增强水凝胶油墨。

为了实现复杂组织再生的三维（3D）微环境，在开发生物材料作为人工细胞外基质（ECM）并具有与天然组织相似的特性方面面临的巨大挑战。在这种情况下，基于多糖的水凝胶通过证明其与天然ECM相似的特性，具有在受损组织再生或器官重建中作为ECM的巨大潜力。仅无细胞或有细胞负载的水凝胶油墨的挤出3D打印在制造用于组织工程应用的所需组合物和体系结构方面更加先进。具有直接物理挤出特性的3D打印技术的发展也是稳定的，具有最佳理化特性和生物相容性的无细胞和细胞负载水凝胶油墨的重要发展方向。在这个研究中，使用过硫酸铵（APS）制备了羧化纤维素纳米晶体（cCNCs），其中TEM，FTIR和XRD分析证实了成功制备了cCNCs。此外，评估了海藻酸钠（SA）水凝胶基质的流变行为对cCNCs（-COOH）和/或黄原胶（XG）（-COOH）的影响。cCNC和XG的掺入控制了水凝胶油墨的流动和剪切稀化行为，从而提高了印刷能力。结果表明，所开发的水凝胶油墨在压缩状态下具有良好的流变性，印刷后保真度和动态力学性能。此外，如定性和定量细胞分析所证实的，在大量水凝胶（水凝胶油墨）上观察到了人类皮肤成纤维细胞（CCD-986Sk）的良好生存能力。