Compressional stress stiffening & softening of soft hydrogels - how to avoid artefacts in their rheological characterisation
Compressional stress stiffening & softening of soft hydrogels - how to avoid artefacts in their rheological characterisation
复制标题
压缩应力硬化
DOI：
10.1039/d3sm00077j
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发表时间：
2023
期刊：
影响因子：
3.4
通讯作者：
Ferraro R
中科院分区：
文献类型：
--
作者：
Ferraro R
水凝胶已经成功地用作细胞外基质的类似物来研究生物过程，例如细胞的迁移、生长、粘附和分化。这些由许多因素控制，包括水凝胶的机械性能;然而，文献中仍然缺少凝胶的粘弹性能和细胞命运之间的一对一相关性。在这项工作中，我们提供了实验证据支持这种知识差距的持久性的可能解释。特别是，我们采用了常见的组织的替代品，如聚丙烯酰胺和琼脂糖凝胶，以阐明一个潜在的陷阱时发生的流变特性的软材料。该问题与（i）在进行流变测量之前施加到样品的法向力有关，这可能容易地将研究结果驱动到材料的线性粘弹性范围之外，特别是当使用（ii）具有不合适尺寸的几何工具（即，太小）。我们证实，仿生水凝胶可以表现出压缩应力软化或硬化，我们提供了一个简单的解决方案来淬灭这些不期望的现象，这可能会导致潜在的误导性结论，如果他们没有减轻一个良好的实践，在进行流变测量，在这项工作中阐明。
Hydrogels have been successfully employed as analogues of the extracellular matrix to study biological processes such as cells' migration, growth, adhesion and differentiation. These are governed by many factors, including the mechanical properties of hydrogels; yet, a one-to-one correlation between the viscoelastic properties of gels and cell fate is still missing from literature. In this work we provide experimental evidence supporting a possible explanation for the persistence of this knowledge gap. In particular, we have employed common tissues' surrogates such as polyacrylamide and agarose gels to elucidate a potential pitfall occurring when performing rheological characterisations of soft-materials. The issue is related to (i) the normal force applied to the samples prior to performing the rheological measurements, which may easily drive the outcomes of the investigation outside the materials' linear viscoelastic regime, especially when tests are performed with (ii) geometrical tools having unbefitting dimensions (i.e., too small). We corroborate that biomimetic hydrogels can show either compressional stress softening or stiffening, and we provide a simple solution to quench these undesired phenomena, which would likely lead to potentially misleading conclusions if they were not mitigated by a good practice in performing rheological measurements, as elucidated in this work.