2.6. In vitro degradation

The hydrolytic and reductive degradation of polymer films and scaffolds were measured in PBS and GSH/PBS solutions, respectively. For hydrolysis, the weighed sample (W₀) was immersed in 10 mL PBS at 37 °C. For reductive degradation, the weighed sample (W₀) was placed in 10 mL GSH/PBS solution (10 mM) at 37°C. For controlled degradation, the samples (W₀) were first immersed in PBS at 37°C for 2 wk, and then immersed into 10 mM GSH/PBS solution at 37°C for another 2 wk. At a predetermined time point, the sample was rinsed 3 times with deionized water, dried in a freeze-dryer for 3 d, and then weighed (W₁). The mass remaining was calculated as W₁/W₀ × 100%. Three samples were used for each polymer at each time point. The IVs were measured for the remained polymer films after degradation in GSH solution for 7 d and 14 d using a viscometer as described above. The mechanical properties of the films after GSH treatment (n=3) were measured as described above. The scaffold morphologies after degradation were observed under an SEM.