Compressive properties of different hydrogel formulations. Compressive properties of hydrogel formulations (r1-r4) were assessed using a mechanical tester (Shimadzu AGS-X universal, electromechanical) with a 10 N load cell. Samples were prepared in cylindrical molds (7 mm in diameter and 5 mm in height) and cured overnight in a humid atmosphere. Hydrogels were then demolded and incubated in PBS for 24 h prior to testing. A digital caliper was used to measure the dimensions of each hydrogel. Hydrogels were then compressed at a head speed of 1 mm/min until sample failure. The compressive modulus was determined by obtaining the slope of the linear region (0.01 -0.1 mm/mm strain) of the stress (kPa) versus strain (mm/mm) curve.