Physics Department, National Technical University of Athens, Athens, Greece.
Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens, Greece.
Biopolymers. 2020 Jun;111(6):e23353. doi: 10.1002/bip.23353. Epub 2020 Mar 30.
We use video particle tracking microrheology (VPTMR) in order to investigate the viscoelasticity of salmon DNA and correlate it to its steady-flow shear-thinning viscosity. Aqueous solutions of DNA are tested in a wide concentration range from the dilute to the semidilute unentangled concentration regime. The observed mean squared displacement shows power-law scaling with lag-time which is equivalent to power-law behavior of the complex modulus as a function of frequency that is, |G (ω)| = S ∙ ω . The relaxation exponent α changes abruptly with concentration in the semidilute regime from about 1 to about 0.5 which is the exponent predicted by the Rouse model. The quasi-property S follows the scaling of viscosity for uncharged polymers near θ-conditions in the semidilute regime that is, with ν = 0.50 - 0.51. The shear-thinning exponent observed by viscometry increases gradually towards the value of 0.5 which has been predicted for Rouse chains under flow. Our findings are in agreement with recent studies of DNA solutions where DNA is treated as a model polymer and addresses the low-molar mass regime of DNA viscoelasticity. This work demonstrates that the combination of passive particle tracking with viscometry can provide a complete picture on the viscoelasticity of DNA-based biopolymer materials.
我们使用视频粒子跟踪微流变学（VPTMR）来研究鲑鱼 DNA 的粘弹性，并将其与稳态剪切稀化粘度相关联。在从稀到未缠结的半稀浓度范围内的宽浓度范围内测试 DNA 的水溶液。观察到的均方根位移随滞后时间呈幂律缩放，这与作为频率函数的复模量的幂律行为等效，即|G（ω）|=S×ω。在半稀区，松弛指数α随着浓度的变化突然从大约 1 变为大约 0.5，这是 Rouse 模型预测的值。准性质 S 在半稀区的θ条件附近遵循无电荷聚合物的粘度标度，即，其中 ν = 0.50-0.51。通过粘度计观察到的剪切稀化指数逐渐增加到 0.5，这是在流动下 Rouse 链预测的值。我们的发现与最近的 DNA 溶液研究一致，在这些研究中，DNA 被视为模型聚合物，并解决了 DNA 粘弹性的低摩尔质量区。这项工作表明，被动粒子跟踪与粘度计的结合可以提供基于 DNA 的生物聚合物材料粘弹性的完整图像。
