Development of a Constitutive Model of a hydrogel derived from a Diaphragmatic Extracellular Matrix

Hydrogels are 3D network structures of polymer chains with high porosity. They can absorb large amounts of water or biological fluid. Due to the high-water content and the soft structure and high porosity, they closely resemble soft living tissue. Several formulations have been derived from the extracellular matrix (ECM) of diaphragmatic muscle tissue, and various protocols have been developed to obtain hydrogels derived from decellularized ECM. These materials can mimic the composition of the source material and are easily injectable. However, there is a significant lack of studies dedicated to the mechanical characterization and derivation of a numerical model of this material, which would enable in silico simulation before experimenting the in vitro tests. Given this need, the aim of this work was to develop a computational model capable of describing the viscoelastic behaviour of hydrogels based on decellularized extracellular matrix (dECM). For this purpose, dynamic mechanical analysis (DMA) tests were conducted under different conditions (cross-linking states of the material and at different temperatures), and a nonlinear optimization algorithm was developed in order to obtain the coefficients of the Prony Series, a mathematical tool used to describe the Generalized Maxwell Model chosen as the physical representation of the material. Finally, the coefficients obtained are used in a finite element model (FEM), which simulate a stress-relaxation test . This computational model can open up the possibility for future studies on the material, while also reducing the number of in vitro experimental analyses.