Interplay of deformability and adhesion on localization of elastic micro-particles in blood flow
Interplay of deformability and adhesion on localization of elastic micro-particles in blood flow
复制标题
DOI：
10.1017/jfm.2018.890
复制
发表时间：
2018-12
影响因子：
3.7
通讯作者：
Huilin Ye;Zhiqiang Shen;Ying Li
中科院分区：
文献类型：
--
作者：
Huilin Ye;Zhiqiang Shen;Ying Li
由于微粒（MP）在生物医学领域的重要应用，其边缘化和粘附已被单独广泛研究。然而，从边缘化到粘附的级联过程应该在 MPs 在血流中的运输中发挥重要作用。据我们所知，过去尚未对此进行过探索。在这里，我们数值研究了弹性 MP 在其变形性和对血管壁的粘附力相互作用下对血管壁的边缘化行为。我们使用格子玻尔兹曼方法和分子动力学分别求解血流中的流体动力学和粒子动力学（包括红细胞（RBC）和弹性MP）。此外，采用随机配体-受体结合模型来捕获弹性 MP 在血管壁上的粘附行为。边际概率用于量化弹性 MP 在墙上的定位。两个无量纲数被认为控制整个过程：毛细管数$Ca$，表示流体流动的粘性力与MP的弹性界面力的比值；以及粘附数$Ad$，表示粘附强度与流体流动的粘性力的比值。我们系统地在数值上改变它们，并获得边缘概率轮廓。我们发现在 $Ca{-}Ad$ 平面上存在两种有利于高边际概率的最优机制。第一个区域，即区域 I，具有高粘附强度和中等颗粒刚度；另一个区域 II 具有中等的粘附强度和较大的颗粒刚度。我们得出的结论是，最佳状态的存在是由颗粒变形性和粘附强度的相互作用决定的。还详细讨论了相应的底层机制。影响 MP 定位的三个主要因素：（i）红细胞和 MP 之间的近壁流体动力碰撞； (ii) 由于墙壁的存在而导致的变形引起的迁移； (iii) MP 与墙壁之间的粘附相互作用。机制（i）和（iii）促进边际化，而（ii）则阻碍边际化。当 MP 位于流道的不同区域（即近壁区域）时，这三个因素发挥不同的作用并相互竞争。在最佳区域 I，粘附优于变形引起的迁移；在区域II中，与近壁流体动力碰撞和粘附的耦合相比，变形引起的迁移很小。找到最佳方案有助于了解血流粘附效应下弹性 MP 在壁上的定位。更重要的是，我们的结果表明，较软的 MP 或较强的粘附力并不总是 MP 本地化的最佳选择。
The margination and adhesion of micro-particles (MPs) have been extensively investigated separately, due to their important applications in the biomedical field. However, the cascade process from margination to adhesion should play an important role in the transport of MPs in blood flow. To the best of our knowledge, this has not been explored in the past. Here we numerically study the margination behaviour of elastic MPs to blood vessel walls under the interplay of their deformability and adhesion to the vessel wall. We use the lattice Boltzmann method and molecular dynamics to solve the fluid dynamics and particle dynamics (including red blood cells (RBCs) and elastic MPs) in blood flow, respectively. Additionally, a stochastic ligand–receptor binding model is employed to capture the adhesion behaviours of elastic MPs on the vessel wall. Margination probability is used to quantify the localization of elastic MPs at the wall. Two dimensionless numbers are considered to govern the whole process: the capillary number $Ca$ , denoting the ratio of viscous force of fluid flow to elastic interfacial force of MP, and the adhesion number $Ad$ , representing the ratio of adhesion strength to viscous force of fluid flow. We systematically vary them numerically and a margination probability contour is obtained. We find that there exist two optimal regimes favouring high margination probability on the plane $Ca{-}Ad$ . The first regime, namely region I, is that with high adhesion strength and moderate particle stiffness; the other one, region II, has moderate adhesion strength and large particle stiffness. We conclude that the existence of optimal regimes is governed by the interplay of particle deformability and adhesion strength. The corresponding underlying mechanism is also discussed in detail. There are three major factors that contribute to the localization of MPs: (i) near-wall hydrodynamic collision between RBCs and MPs; (ii) deformation-induced migration due to the presence of the wall; and (iii) adhesive interaction between MPs and the wall. Mechanisms (i) and (iii) promote margination, while (ii) hampers margination. These three factors perform different roles and compete against each other when MPs are located in different regions of the flow channel, i.e. near-wall region. In optimal region I, adhesion outperforms deformation-induced migration; and in region II, the deformation-induced migration is small compared to the coupling of near-wall hydrodynamic collision and adhesion. The finding of optimal regimes can help the understanding of localization of elastic MPs at the wall under the adhesion effect in blood flow. More importantly, our results suggest that softer MP or stronger adhesion is not always the best choice for the localization of MPs.