Hydrolytic degradation: In vitro degradation of crosslinked
gelatin electrospun membranes was carried out in
PBS solution. The membrane samples were cut into squares
of 25 25 mm2 (triplicate samples were used for statistical
purposes), immersed in 15 mL of PBS (pH 7.4; 0.8 g NaCl;
0.2 g KCl; 1.44 g Na2HPO4.2H2O and 0.2 g KH2PO4 dissolved
in 1 L of distilled water) and incubated in an air circulation
oven (HERAEUS Vacuotherm) at 37 C for 15 days. The pH of
the PBS solution was measured periodically and PBS was
renewed every 72 h. After specific periods of time, a
membrane was removed from the PBS, washed with ultrapure
water and dried in a vacuum oven (JP SELECTA
Vacuotherm) at room temperature until constant mass was
reached. Samples were weighed before and after degradation
in an electronic quartz microbalance (M5P from
Sartorius) with a resolution 0.001 mg. The extent of hydrolytic
degradation (WL) was calculated by: