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

The shear-induced particle diffusivity in the red blood cell suspensions wa s evaluated based on the flow model and experimental results in a rectangul ar flow chamber. The effective diffusivity (D-e) of solute in the particle suspensions is equal to the stationary diffusivity (D-s) of the solute plus the shear-induced particle diffusivity (D-p). The effective diffusivity (D -e) of bovine serum albumin (BSA) in the red blood cell (RBC) ghost suspens ions was determined under diffusion-limited conditions using a total intern al reflection fluorescence (TIRF) method as a function of suspended RBC gho st volume fractions (0.05-0.7) and shear rates (200-1,000 s(-1)). The stati onary diffusivity (D-s) of BSA in RBC ghost suspensions was calculated by M eredith 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 0.35 x 10(-7) to 21.2 x 10(-7) cm(2)/s and it increased with increasing shear rate. Also the shear-induced RBC ghost diff usivity increased as a particle volume fraction increased as well, up to a particle volume fraction of 0.45. However, for RBC ghost volume fractions a bove 0.45, the shear-induced particle diffusivity decreased with increasing particle volume fraction. The shear-induced particle diffusivity in RBC gh ost suspensions is a function of a particle Peeler number (or shear rate) a nd particle volume fractions. The dimensionless particle diffusivity (D-p/a (2)gamma) was investigated as a function of particle volume fraction and th ese results are in good agreement with the literature values.