4.7. Hydrogel Degradation

Hydrogels for degradation, both for observation and for removal of encapsulated cells, were submerged in a solution of 1 mg/mL alginate lyase (Sigma) and 1 mg/mL collagenase 2 (ThermoFisher, Waltham, MA, USA) in PBS. The gels were then placed in an incubator at 37 °C, and occasionally removed to gently swirl at 5 min increments. Gels studied for the rate of degradation rate were removed from solution and their level of degradation was observed. Gels were observed every 15 min and if, at those times, they were mechanically rigid enough to be weighed, their wet weight was recorded, otherwise they were categorized as either partially degraded for gels that were still visibly present to some extent or completely degraded where no gel was visible at all.