| 论文简介 |
Due to the significance in understanding the underlying mechanisms of cell adhesion in biological processes and cell capture in biomedical applications, we numerically investigate the adhesion dynamics of deformable capsules under shear flow by using a three-dimensional computational fluid dynamic model. This model is based on the coupling of the front tracking−finite element method for elastic mechanics of capsule membrane and the adhesion kinetics simulation for adhesive interactions between capsules and functionalized surfaces. Using this model, three distinct adhesion dynamic states are predicted, such as detachment, rolling and firm-adhesion. Specifically, the effects of capsule deformability quantified by Capillary number on the transitions of these three dynamic states are investigated by developing an adhesion dynamic state diagram for the first time. At low Capillary numbers (e.g., Ca < 0.0075), whole-capsule deformation confers the capsule a flattened bottom contacting with the functionalized surface, which hence promotes the rolling-to-firm-adhesion transition. It is consistent with the observations from previous studies that cell deformation promotes the adhesion of cells lying in the rolling regime. However, it is surprisingly found that, at relatively high Capillary numbers (e.g., 0.0075 < Ca < 0.0175), the effect of capsule deformability on its adhesion dynamics is far more complex than just promoting adhesion. High deformability of capsules makes their bottom become a concave shape with no adhesion bonds forming in the middle. The appearance of this specific capsule shape inhibits the transitions of both rolling-to-firm-adhesion and detachment-to-rolling, and it means that capsule deformation no longer promotes the capsule adhesion. Besides, it is interesting to note that, when Capillary number exceeds a critical value (e.g., Ca = 0.0175), the rolling state no longer appears, since capsules exhibit large deviation from spherical shape.
DOI: 10.1039/C6SM01697A
State diagram for adhesion dynamics of deformable capsules under shear flow
Luo ZY， Bai BF* |
(创新港)
