Engineering hydrogel viscoelasticity
Engineering hydrogel viscoelasticity
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DOI：
10.1016/j.jmbbm.2018.09.031
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发表时间：
2019-01-01
影响因子：
3.9
通讯作者：
Ahluwalia, Arti
中科院分区：
文献类型：
--
作者：
Cacopardo, Ludovica;Guazzelli, Nicole;Ahluwalia, Arti
这项研究的目的是找出一种在不改变弹性成分的情况下改变凝胶随时间变化的粘弹性性质的方法。为此，在浓度增加(0%、2%和5%w/v)的葡聚糖水溶液中制备了两种生物医学应用中常用的水凝胶--琼脂糖凝胶和丙烯酰胺，从而增加了粘度。使用浸泡在相同溶液中的商用聚氨酯海绵作为对照，因为与水凝胶不同的是，这些海绵系统中的液体与聚合物网络的结合很差。基于不同恒定应变率下的压缩试验，用epsilon点法表征了样品的粘弹性特性。实验数据与标准的线性实体模型进行了拟合。当对照组的液体粘度增加时，特征松弛时间(Tau)显著增加，瞬时(E-Inst)和平衡(E-Eg)弹性模量几乎保持不变，但在水凝胶中，E-Inst和tau均显著降低。另一方面，正如预期的那样，E-Eg--粘弹性松弛动力学发生后的平衡弹性行为的指示器--被发现与液体的粘度无关。因此，尽管由于液-固相的相互作用，水凝胶的弹性组分和粘性组分不能完全解耦，但我们表明，它们的粘弹性行为可以通过改变水相的粘度来调节。这一简单而有效的策略在机械生物学领域是有用的，特别是在研究细胞对基质粘弹性的响应时，同时保持弹性线索(即平衡弹性系数或准静态刚度)不变。
The aim of this study was to identify a method for modifying the time-dependent viscoelastic properties of gels without altering the elastic component. To this end, two hydrogels commonly used in biomedical applications, agarose and acrylamide, were prepared in aqueous solutions of dextran with increasing concentrations (0%, 2% and 5% w/v) and hence increasing viscosities. Commercial polyurethane sponges soaked in the same solutions were used as controls, since, unlike in hydrogels, the liquid in these sponge systems is poorly bound to the polymer network. Sample viscoelastic properties were characterised using the epsilon-dot method, based on compression tests at different constant strain-rates. Experimental data were fitted to a standard linear solid model. While increasing the liquid viscosity in the controls resulted in a significant increase of the characteristic relaxation time (tau), both the instantaneous (E-inst) and the equilibrium (E-eg) elastic moduli remained almost constant.However, in the hydrogels a significant reduction of both E-inst and tau was observed. On the other hand, as expected, E-eg - an indicator of the equilibrium elastic behaviour after the occurrence of viscoelastic relaxation dynamics - was found to be independent of the liquid phase viscosity.Therefore, although the elastic and viscous components of hydrogels cannot be completely decoupled due to the interaction of the liquid and solid phases, we show that their viscoelastic behaviour can be modulated by varying the viscosity of the aqueous phase. This simple-yet-effective strategy could be useful in the field of mechanobiology, particularly for studying cell response to substrate viscoelasticity while keeping the elastic cue (i.e. equilibrium modulus, or quasi-static stiffness) constant.