The Influence of Printing Parameters and Cell Density on Bioink Printing Outcomes.
The Influence of Printing Parameters and Cell Density on Bioink Printing Outcomes.
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DOI：
10.1089/ten.tea.2020.0210
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发表时间：
2020-12
影响因子：
--
通讯作者：
Atala A
中科院分区：
文献类型：
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作者：
Gillispie GJ;Han A;Uzun-Per M;Fisher J;Mikos AG;Niazi MKK;Yoo JJ;Lee SJ;Atala A
生物墨水的可打印性仍然是许多生物打印应用的一个限制因素。打印参数的选择在很大程度上取决于使用者，并且细胞密度对可打印性的影响尚未得到彻底研究。最近，已经开发出一些方法来更深入地了解打印结果。本研究旨在进一步推进这些方法，并将其应用于研究打印参数（进给速度和流速）以及细胞密度对可打印性的影响。建立了两种打印结构，即交叉阴影结构和5层管结构，作为打印标准并用于确定打印结果。使用进给速度为37.5、75、150、300和600毫米/分钟以及流速为21、42、84、168和336立方毫米/分钟的测试矩阵打印无细胞生物墨水。还以150毫米/分钟和84立方毫米/分钟的速度，用5、10、20和40×10⁶个细胞/毫升的细胞密度打印结构。只有从0.07到2.24平方毫米的速度比（定义为流速除以进给速度）适合进行分析。速度比的增加显著增加了管状结构的高度、宽度和壁厚，但不影响径向精度。对于交叉阴影结构，在不影响孔隙形状（Pr）的情况下，孔隙面积和断丝频率降低。在速度比范围内，进给速度和流速的影响可忽略不计且不一致。尽管流变学有轻微变化，但细胞密度不影响任何打印结果。打印结果主要由速度比决定，在测试范围内控制速度比时，进给速度、流速和细胞密度对打印结果影响很小。这些结果与其他生物墨水和打印条件的相关性需要生物打印界继续研究，同时强调速度比是一个需要报告的关键变量，并表明流变学是一种比打印结果更敏感的测量方法。
Bioink printability persists as a limiting factor towards many bioprinting applications. Printing parameter selection is largely user-dependent, and the effect of cell density on printability has not been thoroughly investigated. Recently, methods have been developed to give greater insight into printing outcomes. This study aims to further advance those methods and apply them to study the effect of printing parameters (feedrate and flowrate) and cell density on printability. Two printed structures, a crosshatch and 5-layer tube, were established as printing standards and utilized to determine the printing outcomes. Acellular bioinks were printed using a testing matrix of feedrates of 37.5, 75, 150, 300, and 600 mm/min and flowrates of 21, 42, 84, 168, and 336 mm3/min. Structures were also printed with cell densities of 5, 10, 20, and 40 × 106 cell/mL at 150 mm/min and 84 mm3/min. Only speed ratios (defined as flowrate divided by feedrate) from 0.07 to 2.24 mm2 were suitable for analysis. Increasing speed ratio dramatically increased the height, width, and wall thickness of tubular structures, but did not influence radial accuracy. For crosshatch structures, the area of pores and the frequency of broken filaments were decreased without impacting pore shape (Pr). Within speed ratios, feedrate and flowrate had negligible, inconsistent effects. Cell density did not affect any printing outcomes despite slight rheological changes. Printing outcomes were dominated by the speed ratio, with feedrate, flowrate, and cell density having little impact on printing outcomes when controlling for speed ratio within the ranges tested. The relevance of these results to other bioinks and printing conditions requires continued investigation by the bioprinting community, as well as highlight speed ratio as a key variable to report and suggest that rheology is a more sensitive measure than printing outcomes.