Büyükurgancı Beyza, Basu Santanu Kumar, Neuner Markus, Guck Jochen, Wierschem Andreas, Reichel Felix
Max Planck Institute for the Science of Light and Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany.
Institute of Fluid Mechanics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
Soft Matter. 2023 Mar 1;19(9):1739-1748. doi: 10.1039/d2sm01515c.
Methyl cellulose (MC) is a widely used material in various microfluidic applications in biology. Due to its biocompatibility, it has become a popular crowding agent for microfluidic cell deformability measurements, which usually operate at high shear rates (>10 000 s). However, a full rheological characterization of methyl cellulose solutions under these conditions has not yet been reported. With this study, we provide a full shear-rheological description for solutions of up to 1% MC dissolved in phosphate-buffered saline (PBS) that are commonly used in real-time deformability cytometry (RT-DC). We characterized three different MC-PBS solutions used for cell mechanical measurements in RT-DC with three different shear rheometer setups to cover a range of shear rates from 0.1-150 000 s. We report viscosities and normal stress differences in this regime. Viscosity functions can be well described using a Carreau-Yasuda model. Furthermore, we present the temperature dependency of shear viscosity and first normal stress difference of these solutions. Our results show that methyl cellulose solutions behave like power-law liquids in viscosity and exhibit first normal stress difference at shear rates between 5000-150 000 s. We construct a general viscosity equation for each MC solution at a certain shear rate and temperature. Furthermore, we investigated how MC concentration influences the rheology of the solutions and found the entanglement concentration at around 0.64 w/w%. Our results help to better understand the viscoelastic behavior of MC solutions, which can now be considered when modelling stresses in microfluidic channels.
甲基纤维素（MC）是生物学中各种微流体应用中广泛使用的材料。由于其生物相容性，它已成为微流体细胞变形性测量中一种流行的拥挤剂，这种测量通常在高剪切速率（>10000 s⁻¹）下进行。然而，尚未有关于这些条件下甲基纤维素溶液的完整流变学表征的报道。通过本研究，我们为溶解在磷酸盐缓冲盐水（PBS）中的浓度高达1%的MC溶液提供了完整的剪切流变学描述，这些溶液常用于实时变形性细胞术（RT-DC）。我们用三种不同的剪切流变仪设置对RT-DC中用于细胞力学测量的三种不同的MC-PBS溶液进行了表征，以覆盖0.1 - 150000 s⁻¹的剪切速率范围。我们报告了该范围内的粘度和法向应力差。粘度函数可以用Carreau-Yasuda模型很好地描述。此外，我们还展示了这些溶液的剪切粘度和第一法向应力差的温度依赖性。我们的结果表明，甲基纤维素溶液在粘度方面表现得像幂律液体，并且在5000 - 150000 s⁻¹的剪切速率下表现出第一法向应力差。我们为每种MC溶液在特定的剪切速率和温度下构建了一个通用粘度方程。此外，我们研究了MC浓度如何影响溶液的流变学，并发现缠结浓度约为0.64 w/w%。我们的结果有助于更好地理解MC溶液的粘弹性行为，现在在对微流体通道中的应力进行建模时可以考虑这些行为。
