Evaluation of shear-induced particle diffusivity in red cell ghosts suspensions

Abstract

The shear-induced particle diffusivity in the red blood cell suspensions was evaluated based on the flow model and experimental results in a rectangular flow chamber. The effective diffusivity (De) of solute in the particle suspensions is equal to the stationary diffusivity (Ds) of the solute plus the shear-induced particle diffusivity (Dp). The effective diffusivity (De) of bovine serum albumin (BSA) in the red blood cell (RBC) ghost suspensions was determined under diffusion-limited conditions using a total internal reflection fluorescence (TIRF) method as a function of suspended RBC ghost volume fractions (0.05-0.7) and shear rates (200-1,000 s,-1). The stationary diffusivity (Ds) of BSA in RBC ghost suspensions was calculated by Meredith and Tobias model. Therefore the shear-induced particle diffusivity undergoing laminar shear flow can be evaluated. The shear-induced RBC ghost diffusivity was ranged from 0.35xl0-7 to 21.2xl0-7 cm2/s and it increased with increasing shear rate. Also the shear-induced RBC ghost diffusivity increased as a particle volume fraction increased as well, up to a particle volume fraction of 0.45. However, for RBC ghost volume fractions above 0.45, the shear-induced particle diffusivity decreased with increasing particle volume fraction. The shear-induced particle diffusivity in RBC ghost suspensions is a function of a particle Peclet number (or shear rate) and particle volume fractions. The dimensionless particle diffusivity (Dρ/a2γ) was investigated as a function of particle volume fraction and these results are in good agreement with the literature values.