2.1.8. Swelling and degradability evaluation

To assess the swelling rate of the hydrogel on the material surface, the samples were freeze-dried and weighed (W₁) and then immersed in PBS at 37 °C. Samples were removed at a preset time, and excess PBS was absorbed with filter paper and weighed (W2). The swelling rate was calculated as follows: Swelling ratio (%) = (W₂–W₁)/W₁ × 100 %.

The degradation properties of the materials were evaluated by degradation experiments. Briefly, samples were immersed in PBS at 37°, weighed after complete swelling (W₁), removed at a predetermined time and weighed after removal of excess water (W_t). The degradation rate equation is as follows: Degradation ratio (%) =(W₁-W_t)/W₁ × 100 %.