Flow behaviour of single vesicles and red blood cells in confined geometry disigned by microfluidic channels

我们计划研究单个囊泡和红细胞在其周围流体动力流场中的变形及其与流场的相互作用。剪切流与单个软体的变形和运动的耦合导致了复杂的动力学现象，如膜表面围绕其内部体积旋转(坦克踏板)、振荡(摆动)和不稳定(翻滚)。在这项实验研究中，我们想要刻画这些变形和运动模式，特别是关于软物体在不同剪切流场中的粘弹材料特性。为了产生这样的流场，我们打算通过软光刻来设计不同几何形状的微流控通道。通过温度诱导的流体-凝胶转变来驱动脂膜，或者使用胆固醇和脂类的二元或三元混合物，可以改变囊泡的粘弹性特性。后者也是已知的形成微观或亚微观大小的区域(“筏”)。按照计划，红细胞的胆固醇含量将有所不同，因为已知它具有显著的生物学和医学意义。此外，红细胞的变形性随着细胞的老化或疟疾、高胆固醇血症和糖尿病等疾病的变化而变化。

We plan to study the deformation of single vesicles and red blood cells in hydrodynamic flow fields around them and their mutual interacting with the flow field. The coupling of the shear flow to the deformation and motion of individual soft object gives rise to complex dynamic phenomena such as a rotation of the membrane surface around its inner volume (tank treading), oscillatory (“swinging”) and unsteady (tumbling). In this experimental study we want to characterize these deformations and regimes of motion especially with respect to the viscoe-lastic material properties of soft objects in different shear flow fields. In order to create such flow fields, we intend to design microfluidic channels of varying geometry by soft lithography. The viscoelastic properties of vesicles should be altered by driving the lipid membrane through its temperature-induced fluid-gel transition or to use a binary or ternary mixture of cholesterol and lipids. The latter ones are also known to form domains (“rafts”) of either mi-croscopic or submicroscopic size. In accordance, the cholesterol content of red blood cells is planned to be varied as it is known to be of eminent biological and medical relevance. Furthermore, the deformability of RBCs changes with aging of cells or in diseases such as malaria, hypercholesterolemia and diabetes mellitus .