The consolidation behavior of silk hydrogels

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Soft Matter Physics

Background:

• Hydrogels possess mechanical and structural properties akin to load-bearing soft tissues.
• They are utilized in tissue restoration and therapeutic factor delivery.
• Accurate mechanical characterization and mathematical modeling are crucial for predicting hydrogel performance.

Purpose of the Study:

• To investigate the mechanical behavior of silk hydrogels under physiological loading conditions.
• To model the time-dependent response of silk hydrogels using established theories.
• To analyze the influence of hydrogel concentration on mechanical properties and permeability.

Main Methods:

• Confined compression creep tests were conducted on silk hydrogels at various concentrations.
• Biot's poroelasticity theory was applied to model the observed time-dependent behavior.
• Linear Terzaghi theory and numerical simulations were used to validate the model and measure permeability.

Main Results:

• The time-dependent response of silk hydrogels under creep loading is consistent with a consolidation mechanism.
• Biot's poroelasticity theory accurately models the observed phenomenological behavior.
• Higher concentration silk hydrogels (8% and 12% w/v) exhibit strain-stiffening, unlike lower concentration gels (4% w/v).
• Permeability coefficients derived from simulations and direct measurements showed good agreement.

Conclusions:

• Silk hydrogels can be effectively modeled using Biot's poroelasticity theory for predicting performance in tissue engineering applications.
• The concentration-dependent strain-stiffening behavior necessitates nonlinear elastic constitutive formulations.
• Deformation-dependent permeability can be represented by empirical formulations.