Skip to Main content Skip to Navigation
Theses

Élasticité du squelette du globule rouge humain - une étude par pinces optiques -

Abstract : The red blood cell (RBC) is able to undergo great shear deformations, mainly when it passes through capillaries with a diameter smaller than its own. This resistance to shear deformations is attributed to its membrane. This membrane is made of a flexible bidimensional protein network which reinforces the inner face of the lipid bilayer. This skeleton is mainly composed of long spectrin filaments (~200 nm) linked together and to the bilayer by junction complexes. In the first part of this work, we measured the shear modulus µ of the intact membrane (lipid bilayer and skeleton) using optical tweezers micromanipulations. Two silica beads bound to the membrane are trapped and used to apply calibrated forces to the membrane. The shear modulus is inferred from the measured deformations and the applied stresses. We found µ = 2.5 +/- 0.4 µN/m, a value comparable but smaller than the ones obtained by other methods. In a second part, the area expansion KC and the shear moduli µC of the free spectrin skeleton - freshly extracted from the membrane - are measured. A RBC is trapped by three silica beads bound to its membrane and the lipid bilayer is dissolved by injection of a detergent. The skeleton remains attached to the beads and is deformed by applying calibrated forces to the beads. The elastic moduli of the two-dimensional spectrin network are inferred from the deformations and the applied stresses. Ones found KC = 4.8 +/- 2.7 µN/m and µC = 2.4 +/- 0.7 µN/m for a 25 mOsm/kg buffer. From this measurements, we can infer the spectrin persistence length, here 5 nm. The measured values are consistent with estimates deduced from experiments carried out on the intact membrane, and agree with theoretical and numerical predictions concerning two-dimensional networks of entropic springs. The influence of the ionic strength and the aging of the skeleton after its extraction are studied in the last part.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00001250
Contributor : Guillaume Lenormand <>
Submitted on : Wednesday, March 20, 2002 - 9:05:03 PM
Last modification on : Friday, May 29, 2020 - 4:01:13 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:53:45 PM

Identifiers

  • HAL Id : tel-00001250, version 1

Citation

Guillaume Lenormand. Élasticité du squelette du globule rouge humain - une étude par pinces optiques -. Biophysique [physics.bio-ph]. Université Pierre et Marie Curie - Paris VI, 2001. Français. ⟨tel-00001250⟩

Share

Metrics

Record views

516

Files downloads

4784