Structural relaxation of dynamic formation of clustering within a extracellular matrix, a simulation model of articular cartilage

Articular cartilage is a composite hydrogel found in animal and human joints, which exhibits unique load-bearing properties that have been challenging to reproduce in synthetic materials and model in molecular dynamics (MD) simulations. We developed a coarse-grained model of a composite hydrogel as a biomimetic model to investigate its unique load-bearing properties. Our composite gel model is composed of an extracellular covalently bonded polymeric matrix and small polymeric particles embedded in the polymer matrix. We find the formation of a dynamic network formed by the embedded particles within the polymer matrix and it is associated with the emergence of prestress in this gel-type of materials. The prestress plays a key role in enhancing the mechanical and load-bearing properties of the gel materials. Our MD simulations of the development of prestress agree semi-quantitatively with osmotic pressure measurements observed in our model composite hydrogel material.