Ls 100

The in-vitro degradation rate of the samples was studied using the degradation test. The initial weight of each freeze-dried hydrogel was measured before soaking in PBS and PBS-containing lipase (w). Then samples were soaked in PBS (0.01 M, pH = 7.4) and PBS-lipase at 37 °C with a rotational speed of 28 rpm (Thermoshaker, LS-100, Thermo Scientific, United States) for 21 days. PBS and PBS-lipase were replaced every 3 days. The lipase enzyme prepared from Pseudomonas cepacia was solved in PBS at a concentration of 0.5 mg/mL. The scaffolds were washed with deionized water to remove the remaining salts, dried with filter paper, and then oven-dried for 24 h. The dry weights of the scaffolds were noted as (Wt). The degradation weight of each scaffold was calculated as stated in the equation below: $Weightloss\left(\%\right)=\left[\frac{W-W_t}{W}\right]\times 100$

The weight loss was measured in correspondence to time to evaluate the rate of biodegradation. After measuring the dry weight, the scaffolds were immersed in 45 mL of phosphate buffered saline (PBS, Biowest Co, USA) at 37 °C and rotated at a speed of 50 rpm in a thermoshaker device (LS‐100, Thermo Scientific) for 14, 21 and 28 days. At the end of each week, the scaffolds were dried and weighed again. The biodegradation percentage of the scaffolds was calculated by the following equation in which W0 is the dry weight and W is the weight of specimen after specific soaking time [19 ].