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Engineering hydrogel viscoelasticity.
Journal of the Mechanical Behavior of Biomedical Materials ( IF 3.9 ) Pub Date : 2018-09-21 , DOI: 10.1016/j.jmbbm.2018.09.031
Ludovica Cacopardo 1 , Nicole Guazzelli 2 , Roberta Nossa 1 , Giorgio Mattei 3 , Arti Ahluwalia 1
Affiliation  

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 (τ), both the instantaneous (Einst) and the equilibrium (Eeq) elastic moduli remained almost constant.

However, in the hydrogels a significant reduction of both Einst and τ was observed. On the other hand, as expected, Eeq – 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.



中文翻译:

工程水凝胶粘弹性。

这项研究的目的是确定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质的方法。为此,在葡聚糖的水溶液中以增加的浓度(0%,2%和5%w / v)制备了两种通常用于生物医学应用的水凝胶,琼脂糖和丙烯酰胺,并因此增加了粘度。浸泡在相同溶液中的商用聚氨酯海绵被用作对照,因为与水凝胶不同,这些海绵体系中的液体很难与聚合物网络结合。基于不同恒定应变率下的压缩试验,使用ε-点法对样品的粘弹性进行表征。实验数据拟合到标准线性实体模型。τ),无论是瞬时(E仪器)和平衡(E当量弹性模量几乎保持恒定。

然而,在水凝胶中,两者的显着降低 E仪器τ被观测到。另一方面,正如预期的那样,E当量 –粘弹性松弛动力学发生后平衡弹性行为的指标–被发现与液相粘度无关。

因此,尽管水凝胶的弹性和粘性成分由于液相和固相的相互作用而不能完全解耦,但我们表明,可以通过改变水相的粘度来调节它们的粘弹性行为。这种简单有效的策略可能在机械生物学领域很有用,尤其是在研究细胞对基质粘弹性的反应的同时保持弹性提示(即平衡模量或准静态刚度)恒定的情况下。

更新日期:2018-09-21
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