Beyond linear response: Time-resolved rheology of interpenetrating biopolymer composites

The design of functional biological materials for use as three dimensional cellular scaffolds and bioprinting requires exquisite control of both structure and mechanical properties of multicomponent systems. In 3-D printing applications, functionality and microscale structure must be maintained in conditions where large strain deformations occur at all scales. In this talk, we will discuss the nonlinear mechanical response of a biologically derived interpenetrating network composed of gelatin, fibrin and a non-specific enzymatic crosslinker through the use of Large Amplitude Oscillatory Strain (LAOS) rheology. Using a time-resolved approach, the sequence of physical processes (SPP) framework, we quantify the relationship between the microscopic interplay of the constituents to determine the non-additive rheology of the composite when subjected to large deformations. Specifically, our results show that under fixed protein concentrations and polymerization conditions, the enzymatic crosslinking moieties are not equivalently distributed throughout the composite network compared to the single component systems. Additionally, we will show that our statistical analysis of the SPP results provides a generic and robust method for straightforward physical interpretation of LAOS rheology.