Department of Medical Biotechnology and Translational Medicine, University of Milan, 20129 Milano, Italy.
Soft Matter. 2018 May 2;14(17):3288-3295. doi: 10.1039/c8sm00373d.
The viscosity of gel-forming fluids is notoriously complex and its study can benefit from new model systems that enable a detailed control of the network features. Here we use a novel and simple microfluidic-based active microrheology approach to study the transition from Newtonian to non-Newtonian behavior in a DNA hydrogel whose structure, connectivity, density of bonds, bond energy and kinetics are strongly temperature dependent and well known. In a temperature range of 15 °C, the system reversibly and continuously transforms from a Newtonian dispersion of low-valence nanocolloids into a strongly shear-thinning fluid, passing through a set of intermediate states where it behaves as a power-law fluid. We demonstrate that the knowledge of network topology and bond free energy enables to quantitatively predict the observed behavior using established rheology models.
凝胶形成流体的黏度非常复杂，其研究可以受益于新的模型系统，这些系统可以对网络特征进行详细控制。在这里，我们使用一种新颖而简单的基于微流控的主动微流变学方法来研究 DNA 水凝胶中从牛顿到非牛顿行为的转变，该水凝胶的结构、连通性、键密度、键能和动力学强烈依赖于温度且众所周知。在 15°C 的温度范围内，该系统可在低结合价纳米胶体的牛顿分散体和强剪切稀化流体之间进行可逆且连续的转换，经过一系列中间状态，其表现为幂律流体。我们证明，网络拓扑和键自由能的知识可以使用已建立的流变学模型来定量预测观察到的行为。
