Blood flowing through microvascular bifurcations has been an active research topic for many decades, while the partitioning pattern of nanoscale solutes in the blood remains relatively unexplored. Here we demonstrate a multiscale computational framework for direct numerical simulation of the nanoparticle (NP) partitioning through physiologically relevant vascular bifurcations in the presence of red blood cells (RBCs). The computational framework is established by embedding a particulate suspension inflow-outflow boundary condition into a multiscale blood flow solver. The computational framework is verified by recovering a tubular blood flow without a bifurcation and validated against the experimental measurement of an intravital bifurcation flow. The classic Zweifach-Fung (ZF) effect is shown to be well captured by the method. Moreover, we observe that NPs exhibit a ZF-like heterogeneous partition in response to the heterogeneous partition of the RBC phase. The NP partitioning prioritizes the high-flow-rate daughter branch except for extreme (large or small) suspension flow partition ratios under which the complete phase separation tends to occur. By analyzing the flow field and the particle trajectories, we show that the ZF-like heterogeneity in the NP partition can be explained by the RBC-entrainment effect caused by the deviation of the flow separatrix preceded by the tank treading of RBCs near the bifurcation junction. The recovery of homogeneity in the NP partition under extreme flow partition ratios is due to the plasma skimming of NPs in the cell-free layer. These findings, based on the multiscale computational framework, provide biophysical insights to the heterogeneous distribution of NPs in microvascular beds that are observed pathophysiologically.

中文翻译：

---

通过微血管分支细胞血源性纳米粒子的异质分配。

数十年来，流经微血管分叉的血液一直是活跃的研究主题，而血液中纳米级溶质的分配模式仍然相对未开发。在这里，我们演示了在存在红细胞（RBC）的情况下通过生理相关的血管分叉对纳米颗粒（NP）进行分区的直接数值模拟的多尺度计算框架。通过将颗粒悬浮液的流入-流出边界条件嵌入多尺度血流求解器中来建立计算框架。通过恢复无分叉的管状血流来验证计算框架，并针对体内分叉流的实验测量进行验证。该方法显示了经典的茨威法赫-冯（ZF）效果。此外，我们观察到，NPs响应RBC相的异质性分区表现出ZF样的异质性分区。NP划分优先考虑高流速子分支，但极端（大或小的）悬浮流分配比率除外，在该比率下会发生完全的相分离。通过分析流场和颗粒轨迹，我们发现NP分区中的ZF样异质性可以由分流结点附近分叉处的RBC罐踩踏之前流动分离层的偏离引起的RBC夹带效应来解释。 。在极端流动分配比下，NP分配中的同质性恢复归因于无细胞层中NP的等离子撇除。这些发现基于多尺度计算框架，