In vitro enzymatic degradation The in vitro biodegradation test of FCA and FCA/COSs was performed by the collagenase digestion according to the previous study [26] with tiny modifications. In brief, known dry weights of each specimen (W0) were incubated in PBS (pH 7.4) containing 50 units (of 125 CDU) collagenase (type IfromClostridium histolyticum) at 37 ◦C for 12 days. The incubated scaffolds were collected at different time intervals and washed with distilled water before freeze drying. The dried scaffold weights weremeasured (W1) at each time and the corresponding percentages of weight losses were calculated according to the formula EqWD represents the in vitro degradation percentage.