Nonlinear rheology of biologically derived interpenetrating networks

The extracellular media (ECM) is a combination of different biological polymer networks that provide structure and scaffolding for the support and growth of cells in tissues, regulate function, and can play an important role in disease triggering, onset and progression. In this work, we will discuss the rheological response of biologically derived interpenetrating networks (IPNs) composed of gelatin-fibrin and collagen-fibrin with varying degrees of inter-and intra- chain crosslinking. These interpenetrating networks have demonstrated their ability to endure high strains. Using a novel framework to analyze large amplitude oscillatory rheology (LAOS) raw stress response data, we measure the equivalent transient storage and loss moduli over cycles of different frequencies and amplitudes of IPNs developed for three dimensional cell culture. Specifically, we will demonstrate that the materials transition continuously gradually from linear to nonlinear responses with an increase in the applied amplitude and strain rate. We will also discuss the impact that strain and strain rate has on the history (plasticity) of the material through the cycle as a function of biopolymer type and crosslinking concentration.