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Accueil du site > À la une > High aspect ratio submicron channels using wet etching. Application to the dynamics of red blood cell transiting through biomimetic splenic slits"

High aspect ratio submicron channels using wet etching. Application to the dynamics of red blood cell transiting through biomimetic splenic slits"

Priya Gambhire, Scott Atwell,† Cécile Iss,† Frédéric Bedu, Igor Ozerov, Catherine Badens, Emmanuèle Helfer, Annie Viallat and Anne Charrier
Réf : Small 2017, 1700967

Résumé :

The two most frequent red blood cells (RBC) diseases, the sickle cell disease (SCD) and the hereditary spherocytosis (HS), are characterized by an increase of the cell rigidity. This leads to circulatory problems in thin capillaries and the inter-endothelial splenic slits. The latter have sub-micron dimensions and play the role of RBC filter ; less deformable cells are trapped at the slits entrance and are further eliminated by white blood cells. Despite the numerous studies on blood stream, the role of deformation parameters, i.e., the mechanical parameters of RBCs that control their behavior in micro-flow are yet not understood.
We developed a microfluidic device of PDMS containing slits with physiological dimensions. The submicron slits are obtained by soft lithography as replica from a silicon master mold itself obtained using an audacious combination of standard UV lithography and anisotropic wet etching.
These devices enabled revealing novel modes of deformations of healthy and diseased RBCs squeezing through splenic-like slits under physiological interstitial pressures. At the slit exit, the cytoskeleton of HS RBCs seemed to be detached from the lipid membrane whereas RBCs from healthy donors (H) and from patients with SCD exhibited peculiar tips at their front. These tips disappeared much slower in patients’ cells, allowing estimating a threefold increase in RBC cytoplasmic viscosity in SCD. Measurements of time and rate of RBC sequestration in the slits allowed quantifying the massive trapping of HS RBCs.

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Déformation d’un globule rouge traversant une fente sub-micronique
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Passage d’un globule rouge sphérocytaire dans une fente sub-micronique