Quantification and macroscopic modeling of the nonlinear viscoelastic behavior of strained gels with varying fibrin concentrations

Abstract

The mechanical properties of fibrin gels under uniaxial strains have been analyzed for low fibrin concentrations using a free-floating gel device. We were able to quantify the viscous and elastic moduli of gels with fibrin concentration ranging from 0.5 to 3 mg/ml, reporting significant differences of biogels moduli and dynamical response according to fibrin concentration. Furthermore, considering sequences of successively imposed step strains has revealed the strain-hardening properties of fibrin gels for strain amplitude below 5%. This nonlinear viscoelastic behavior of the gels has been precisely analyzed through numerical simulations of the overall gel response to the strain steps sequences. Phenomenological power laws relating the instantaneous and relaxed elasticity moduli to fibrin concentration have been validated, with concentration exponent in the order of 1.2 and 1.0, respectively. This continuous description of strain-dependent mechanical moduli was then used to simulate the biogel behavior when continuously time-varying strains are applied. We discuss how this experimental setup and associated macroscopic modeling of fibrin gels enable a further quantification of cell traction forces and mechanotransduction processes induced by biogel compaction or stretching.

Rheological characterization and dissolution kinetics of fibrin gels crosslinked by a microbial transglutaminase

“…The very unusual profile of the storage modulus evolution around the sol/gel transition may be related to the already reported nonlinear viscoelastic behavior of fibrin gels. 25 Moreover, this gel does not rapidly reach an equilibrium state as it continuously evolves with time over several hours as indicated by the increase of GЈ. Transglutaminase can stabilize this structure by covalently crosslinking the ␣-and ␥-chains of fibrin.…”

A fibrinogen-based precision microporous scaffold for tissue engineering

“…The Young's modulus of native heart tissue has been reported to be upwards of 67kPa [24] and esophageal tissue has been reported to be 60kPa [25]. In comparison, typical fibrin hydrogels are inherently weak constructs with a Young's modulus of 0.94kPa and 6.49kPa when starting fibrinogen concentrations are 0.5mg/mL to 3.0mg/mL respectively [26]. At higher fibrinogen concentrations, such as those of the commercially available fibrin based adhesives, hydrogels made with 30mg/mL and 70mg/mL fibrinogen have Young's modulus of 15.8kPa and 31.1kPa respectively [27].…”

Biaxial failure properties of planar living tissue equivalents

“…10,11 The subfailure viscoelastic properties of tissue equivalents have been successfully measured using rheometric techniques. 10,12 However, these methods are valid only for small deformations and do not provide failure data. Knowledge of the full spectrum of physical properties of engineered tissue substitutes is clearly needed to guide their rational design.…”