Q. Zhu, R.J. Asaro, and Z. Peng (USA)
RBC membrane, 3D model, strain-unstiffening, mode switching
The erythrocyte (red blood cell, or RBC) membrane, in cluding a lipid bilayer and a protein skeleton composed mostly of actin and spectrin, is routinely subjected to large deformations as the cell circulates throughout the body and squeezes through capillaries. We investigate the me chanical properties of this composite membrane by using a molecular-based model which incorporates a state-of the-art understanding of the 3D molecular architecture of the skeleton, the skeleton-bilayer connectivity, the fluid structure interaction, and the constitutive law of the spec trin with stress-induced unfolding. With this paradigm, we perform numerical simulations of the membrane skeleton under shearing deformations, and show that in larger defor mations, a distinctive strain-unstiffening accompanies the onset of domain unfolding. Another important finding is the existence of mode switching in thermal fluctuations, which may have significant effects on the mechanics and physiological performance of the membrane. It may also be important in our interpretation of recent experiments on membrane stiffness using microrheology methods.
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