Novel 3D computational method reveals nano-to-microscale particle dispersion behaviors in tubular blood flow

Blood is a biological fluid predominantly suspended with red blood cells (RBCs) and other cells and biomolecules with sizes ranging from nanometers to micrometers. Understanding the transport of particulates of disparate sizes in blood can potentially lead to optimal design of drug carriers, and provide better understanding and intervention of vascular diseases. Although scientists have studied the transport of nanoscale or microscale particles in blood flow separately using different methods, questions arise as to whether nanoscale particles share similar dispersion characteristics to microscale particles. This calls for a systematic investigation of the dispersion of particles across nano-to-microscale sizes under a unified methodological framework.

In a recent study, Liu et al. applied a novel 3D multiscale computational framework to study the dispersion of rigid, spherical particles with sizes across nano-to-micrometer scales in a tubular blood flow. The researchers investigated the particle dispersion characteristics by considering rich suspension physics including thermal fluctuation, RBC-particle interactions, RBC deformability and vessel wall-bounded confinement, revealing strong correlations between the non-uniform distribution of particle radial diffusivity and the radial distribution of particle concentration as the system approaches equilibrium.

The researchers found that nanoscale particles are more subject to collisions with fast-moving fluid molecules, leading to a non-uniform, smoothly-dispersed distribution across the vessel radius, while microscale particles interact more with RBCs concentrated at the core of the vessel, resulting in excessive concentrations near the vessel wall, a phenomenon called margination. The transition from dispersion to margination under physiological conditions occurs at particle sizes around 1 micron.

This work demonstrates the first particle-level multiscale computational framework that efficiently bridges the particle dispersive behaviors at two distinct scales, providing mechanistic insights to the particle size-induced dispersion-to-margination transition.

Source: “A unified analysis of nano-to-microscale particle dispersion in tubular blood flow,” by Z. Liu, J. R. Clausen, R. R. Rekha, and C. K. Aidun, Physics of Fluids (2019). The article can be accessed at https://doi.org/10.1063/1.5110604 .