Shear rheology of hydrogels was performed on a commercial shear rheometer (ARES,
Rheometric Scientific) with parallel plate geometry. Data acquisition was done in TA
Orchestrator software (TA Instruments). Fibrin hydrogels were prepared by
polymerizing fibrin solution between two circular cover glasses (diameter, 24 mm;
Menzel) with a 150-μm gap and sealed with silicon oil (Baysilone, medium
viscosity; Bayer) to prevent drying of the gel. The two cover glasses were fixed to
the steel plates of the rheometer with double-sided adhesive tape (tesa SE). A normal
contact force of 0.1 N was applied to the sample, which resulted in a gap spacing of
approximately 175 μm between the plates. Prestrain sweeps were executed by
changing the prestrain from 1 to 500%, superposed by an oscillating strain with an
amplitude smaller than 10% of the prestrain value.
For tensile tests of fibrin gels, a material testing machine (Z005, TestXpert II,
Zwick Roell) equipped with a load cell (Z6FD1, HBM) was used. The initial sample
geometry was approximately 5 mm × 20 mm × 0.2 mm. Fibrin gels were
physically clamped and stretched at a constant rate of 10 mm/min until samples
broke.
Rheometric Scientific) with parallel plate geometry. Data acquisition was done in TA
Orchestrator software (TA Instruments). Fibrin hydrogels were prepared by
polymerizing fibrin solution between two circular cover glasses (diameter, 24 mm;
Menzel) with a 150-μm gap and sealed with silicon oil (Baysilone, medium
viscosity; Bayer) to prevent drying of the gel. The two cover glasses were fixed to
the steel plates of the rheometer with double-sided adhesive tape (tesa SE). A normal
contact force of 0.1 N was applied to the sample, which resulted in a gap spacing of
approximately 175 μm between the plates. Prestrain sweeps were executed by
changing the prestrain from 1 to 500%, superposed by an oscillating strain with an
amplitude smaller than 10% of the prestrain value.
For tensile tests of fibrin gels, a material testing machine (Z005, TestXpert II,
Zwick Roell) equipped with a load cell (Z6FD1, HBM) was used. The initial sample
geometry was approximately 5 mm × 20 mm × 0.2 mm. Fibrin gels were
physically clamped and stretched at a constant rate of 10 mm/min until samples
broke.