Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 0C5, Canada.
Int J Mol Sci. 2023 Feb 15;24(4):3889. doi: 10.3390/ijms24043889.
Reconstituted hydrogels based on the self-assembly of acid-solubilized collagen molecules have been extensively used as in vitro models and precursors in biofabrication processes. This study investigated the effect of fibrillization pH-ranging from 4 to 11-on real-time rheological property changes during the gelation of collagen hydrogels and its interplay with the properties of subsequently biofabricated dense collagen matrices generated via automated gel aspiration-ejection (GAE). A contactless, nondestructive technique was used to characterize the temporal progression in shear storage modulus (G', or stiffness) during collagen gelation. There was a relative increase in G' of the hydrogels from 36 to 900 Pa with an increase in gelation pH. Automated GAE, which simultaneously imparts collagen fibrillar compaction and alignment, was then applied to these precursor collagen hydrogels to biofabricate native extracellular matrix-like densified gels. In line with viscoelastic properties, only hydrogels fibrillized in the 6.5 < pH ≤ 10 range could be densified via GAE. There was an increase in both fibrillar density and alignment in the GAE-derived matrices with an increase in gelation pH. These factors, combined with a higher G' in the alkaline precursor hydrogels, led to a significant increase in the micro-compressive modulus of GAE-densified gels of pH 9 and 10. Furthermore, NIH/3T3 fibroblast-seeded GAE-derived matrices densified from gels fibrillized in the pH range of 7 to 10 exhibited low cell mortality with >80% viability. It is anticipated that the results of this study can be potentially applicable to other hydrogel systems, as well as biofabrication techniques involving needles or nozzles, such as injection and bioprinting.
基于酸溶性胶原分子自组装的再水合水凝胶已被广泛用作体外模型和生物制造过程中的前体。本研究考察了纤维形成 pH 值范围从 4 到 11 对胶原水凝胶胶凝过程中实时流变性质变化的影响及其与通过自动凝胶抽吸-喷射 (GAE) 生成的随后生物制造的致密胶原基质的性质的相互作用。使用非接触、非破坏性技术来表征胶原凝胶化过程中剪切储能模量 (G'，或刚度) 的时间进展。随着凝胶化 pH 值的增加，水凝胶的 G'相对增加了 36 到 900 Pa。然后，将自动 GAE 应用于这些前体胶原水凝胶，以生物制造类似天然细胞外基质的致密凝胶。与粘弹性性质一致，只有在 6.5 < pH ≤ 10 范围内纤维形成的水凝胶才能通过 GAE 致密化。随着凝胶化 pH 值的增加，GAE 衍生基质中的纤维密度和取向都增加了。这些因素，加上碱性前体水凝胶中 G'较高，导致 pH 为 9 和 10 的 GAE 致密化凝胶的微压缩模量显著增加。此外，在 pH 值为 7 到 10 的范围内纤维形成的凝胶中致密化的 NIH/3T3 成纤维细胞接种的 GAE 衍生基质的细胞死亡率低，存活率超过 80%。预计本研究的结果可以潜在地应用于其他水凝胶系统以及涉及针或喷嘴的生物制造技术，如注射和生物打印。
