2.3 Mechanical properties
The effect of the agarose concentration on the Young’s modulus of the
agarose-collagen hydrogels was evaluated by uniaxial compression test.
The correlation with time and temperature was also investigated.
Briefly, the hydrogel samples were incubated in PBS at 37 °C in a
humidified atmosphere with 5% CO2. At fixed time points
(0, 1, 4, and 8 days), cylinders of 8 mm were punched out and loaded
into the testing chamber. All tests were performed with a universal
testing machine ZwickiLine (Zwick Roell, Germany) fitted with 10 N load
cell. Loaded samples were hydrated in PBS at 37 °C and subjected to
compression with a displacement rate of 0.01 mm/s, until 80% strain
(L. C. Gallo et al., 2018;
Monaco, Cholas, Salvatore, Madaghiele, &
Sannino, 2017). The compressive modulus was calculated by linear
fitting between 2 and 10% of strain of the stress-strain curve. The
test was performed in triplicate for each sample type and time point.