Bioengineering Institute of Technology, Universitat Internacional de Catalunya, Josep Trueta, 08195 Sant Cugat del Vallès, Barcelona, Spain; Department of Basic Sciences, Faculty of Medicine and Health Science, Universitat Internacional de Catalunya, JosepTrueta, 08195 Sant Cugat del Vallès, Barcelona, Spain.
Bioengineering Institute of Technology, Universitat Internacional de Catalunya, Josep Trueta, 08195 Sant Cugat del Vallès, Barcelona, Spain; Department of Basic Sciences, Faculty of Medicine and Health Science, Universitat Internacional de Catalunya, JosepTrueta, 08195 Sant Cugat del Vallès, Barcelona, Spain.
Int J Biol Macromol. 2023 Dec 31;253(Pt 7):127461. doi: 10.1016/j.ijbiomac.2023.127461. Epub 2023 Oct 16.
Printability in 3D extrusion bioprinting encompasses extrudability, filament formation, and shape fidelity. Rheological properties can predict the shape fidelity of printed hydrogels. In particular, tan(δ), the ratio between loss (G'') and storage (G') modulus (G''/G'), is a powerful indicator of printability. This study explores the effect of different salt, sucrose, and MC concentrations on tan(δ), and therefore the printability of methylcellulose (MC) hydrogels. Salt and sucrose increased G', lowering tan(δ) and enabling printing of scaffolds with high shape fidelity. Conversely, MC concentration increased G'' and G', having a lesser effect on tan(δ). Shape fidelity of three formulations with similar G' but varying tan(δ) values were compared. Higher tan(δ) led to reduced height, while lower tan(δ) improved shape fidelity. Cell viability increased when reducing MC content, extrusion rate, and nozzle gauge. Higher MC concentration (G' > 1.5 kPa) increased the influence of needle size and extrusion rate on cell viability. Hydrogels with G' < 1 kPa could be extruded at high rates with small nozzles, minimally affecting cell viability. This work shows a direct relationship between tan(δ) and printability of MC-based hydrogels. Lowering the complex modulus of hydrogels, mitigates extrusion stress, thus improving cell survival.
3D 挤出式生物打印的可打印性包括可挤出性、丝材成型和形状保真度。流变性能可以预测打印水凝胶的形状保真度。特别是损耗（G"）与储能（G'）模量（G''/G'）的比值 tan(δ)，是可打印性的有力指标。本研究探讨了不同盐、蔗糖和 MC 浓度对 tan(δ)的影响，进而对甲基纤维素（MC）水凝胶的可打印性的影响。盐和蔗糖增加了 G'，降低了 tan(δ)，使高形状保真度支架的打印成为可能。相反，MC 浓度增加了 G''和 G'，对 tan(δ)的影响较小。比较了三种具有相似 G'但 tan(δ)值不同的配方的形状保真度。较高的 tan(δ)导致高度降低，而较低的 tan(δ)则提高了形状保真度。当降低 MC 含量、挤出速率和喷嘴规格时，细胞活力增加。较高的 MC 浓度（G'>1.5kPa）增加了针头尺寸和挤出速率对细胞活力的影响。G'<1kPa 的水凝胶可以用较小的喷嘴高速挤出，对细胞活力的影响最小。这项工作表明，MC 基水凝胶的 tan(δ)与可打印性之间存在直接关系。降低水凝胶的复合模量，减轻挤出应力，从而提高细胞存活率。
