2.3.5. Swelling and Degradation Test

For swelling and degradation test, the hydrogels were prepared using the same method as described for scanning electron microscopy observation, but using the PDMS mold with different height (height of 2 mm). Bioink prepolymer solution was cross-linked under three conditions (ion, UV, and ion + UV). The prepared hydrogels were then conditioned in 1 mL DMEM (10% FBS, 1% P/S). After 24, 48, and 72 h, the liquid remaining on the hydrogel surface was removed, and the weight of the hydrogel was recorded. The swollen hydrogel was frozen at −80 °C and lyophilization was performed. The weight of the lyophilized hydrogel was recorded. The degrees of swelling and degradation were measured, respectively, by mass swelling ratio and percent mass remaining.