Bioink, a key element of three-dimensional (3D) bioprinting, is frequently engineered to achieve improved printing performance. Viscoelasticity related to rheological properties is correlative of the printability of bioink for extrusion bioprinting, which affects the complexity of printing 3D structures. This article shows the use of hydroxyethyl cellulose (HEC) as a rheological additive for engineering bioink to improve the printability without reducing the biocompatibility. Different concentrations of HEC were added to four types of bioink, namely, reagent-crosslinked, temperature-dependent phase change, ultraviolet-polymerized, and composite hydrogel bioinks, to investigate the effect on the viscoelasticity properties, print fidelity, and other printed scaffold properties. The results indicate that HEC is able to increase the rheological properties by 100 times to stabilize complex structures and improve the printing fidelity to narrow the gap between the design value and theoretical value, even converting nonviscous ink into directly printable ink, as well as tune the swelling ratio for better molecular permeability. The degradation of bioink can also be tuned by the addition of HEC. Moreover, this bioink is biocompatible for cell lines and primary cells. HEC is expected to be widely used in 3D extrusion-based bioprinting.

中文翻译：

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羟乙基纤维素作为流变添加剂用于调节挤出印刷适性和支架性能

生物墨水是三维 (3D) 生物打印的关键要素，经常被设计用于提高打印性能。与流变特性相关的粘弹性与用于挤出生物打印的生物墨水的可打印性相关，这会影响打印 3D 结构的复杂性。本文展示了使用羟乙基纤维素 (HEC) 作为工程生物墨水的流变添加剂，以在不降低生物相容性的情况下提高印刷适性。将不同浓度的 HEC 添加到四种类型的生物墨水中，即试剂交联、温度依赖性相变、紫外线聚合和复合水凝胶生物墨水，以研究对粘弹性、打印保真度和其他打印支架特性的影响. 结果表明，HEC 能够将流变性能提高 100 倍，稳定复杂结构，提高印刷保真度，缩小设计值与理论值之间的差距，甚至可以将非粘性油墨转化为可直接印刷的油墨，并调节更好的分子渗透性的溶胀比。生物墨水的降解也可以通过添加 HEC 来调节。此外，这种生物墨水与细胞系和原代细胞具有生物相容性。HEC 有望广泛应用于基于 3D 挤出的生物打印。生物墨水的降解也可以通过添加 HEC 来调节。此外，这种生物墨水与细胞系和原代细胞具有生物相容性。HEC 有望广泛应用于基于 3D 挤出的生物打印。生物墨水的降解也可以通过添加 HEC 来调节。此外，这种生物墨水与细胞系和原代细胞具有生物相容性。HEC 有望广泛应用于基于 3D 挤出的生物打印。