• Appshaw, Paul
• Hanna, Simon
• Seddon, Annela M.

Abstract

To accurately represent the morphological and elastic properties of a human red blood cell, Fu et al. [Fu {et al., Lennard-Jones type pair-potential method for coarse-grained lipid bilayer membrane simulations in LAMMPS}, 2017, {210}, 193-203]. recently developed a coarse-grained molecular dynamics model with particular detail in the membrane. % {in silico}, , employed utilising the molecular dynamics package LAMMPS. <br/>However, such a model accrues an extremely high computational cost for whole-cell simulation when assuming an appropriate length scaling - that of the bilayer thickness. To date, the model has only simulated "miniature" cells in order to circumvent this, with the {a priori} assumption that these miniaturised cells correctly represent their full-sized counterparts. The present work assesses the validity of this approach, by testing the scale invariance of the model through simulating cells of various diameters; first qualitatively in their shape evolution, then quantitatively by measuring their bending rigidity through fluctuation analysis. Cells of diameter of at least $0.5 {m}$ were able to form the characteristic biconcave shape of human red blood cells, though smaller cells instead equilibrated to bowl-shaped stomatocytes. Thermal fluctuation analysis showed the bending rigidity to be constant over all cell sizes tested, and consistent between measurements on the whole-cell and on a planar section of bilayer. This is as expected from the theory on both counts. Therefore, we confirm that the evaluated model is a good representation of a full-size RBC when the model diameter is $ 0.5 {m}$, in terms of the morphological and mechanical properties investigated.

Topics

• impedance spectroscopy
• theory
• simulation
• molecular dynamics