MD simulation of colloidal particle transportation in a fiber matrix

Surface glycocalyx, as a barrier to material exchange between circulating blood and body tissues, can be treated as a periodic square array of cylindrical fibers. Previous study treated the glycocalyx as porous media and simulated by continuum theory. However, it has recently been found that a relatively hexagonal fibre-matrix structure may be responsible for the ultrafiltration properties of microvascular walls. The fibre-matrix is an underlaying three-dimensional mesh-work with a fibre diameter of 10-12 nm and characteristic spacing of about 20 mn. The porous medium model does not consider the particle size, when the particle size is comparable to the fibre spacing, the porous medium assumption may not be appropriate to study the permeable characteristics of nanosize particle in such fibre-matrix structure. Molecular dynamics (MD) simulation is a powerful method to simulate the fluid flow at the molecular level, it has been applied successfully in many fields including hydrodynamics and demonstrated surprising results at nanoscale which is different from their macroscopic counterparts. In this study we use MD to investigate the permeable characteristics of nano-particle in a quasi-periodic ultra-structure of the endothelial glycocalyx. As the first attempt, fibre-matrix is simplified as a two dimensional periodic system in which the colloidal particles, fluid solvent, fibers are all treated as atomic systems, and the study is focused on the effect of particle size on particle motion in fiber matrix.