Due to the high computational cost of full-cell coarse-grained molecular dynamics modelling, being able to simulate "miniature" cells that effectively represent their full-sized counterparts would be highly advantageous. To accurately represent the morphological and elastic properties of a human red blood cell in silico, such a model is employed utilising the molecular dynamics package LAMMPS. The scale invariance of the model is first tested qualitatively by following the shape evolution of red blood cells of various diameters, then quantitatively by evaluating the membrane shear modulus from simulations of optical tweezer-style stretching. Cells of physical diameter of at least 0.5μm were able to form the characteristic biconcave shape of human red blood cells, though smaller cells instead equilibrated to bowl-shaped stomatocytes. A positive correlation was found between the cell size and both magnitude of deformation from optical tweezer stretching and scaled shear modulus, indicating a lack of scale invariance in the models elastic response. However, the stable morphology and measured shear modulus of the 0.5 – 1.0μm diameter cells are deemed close enough to past in vitro studies on human red blood cells for them to still offer valuable use in making simplified predictions of whole-cell mechanics.

A coarse-grained red blood cell model is subjected to optical tweezer-style stretching, with membrane shear-modulus calculated. Results from the 0.5 − 1.0µm diameter cells show good agreement with past in vitro studies on human red blood cells.

The scale-invariance of a coarse-grained molecular dynamics model of a red blood cell is investigated through fluctuation analysis, justifying the use of “miniature cells” in silico.