FIG. 1.

Characterization of scaffold porosity and degradation with various concentrations of MDI crosslinker used in the villus layer of the scaffold. (A) Scaffold porosity was not significantly different between the different MDI concentrations. (B) Mass loss of scaffolds after 35 days (5 weeks) of in vitro degradation. Six percent MDI had slower degradation compared to 2% in both media and digestive media. The differences were statistically different in media between 2% and 6% MDI at 21, 28, and 35 days with p-values of 0.0252, 0.202, and 0.0013, respectively (indicated by red *). Statistical differences existed in the digestive media at 14, 21, 28, and 35 days with p-values of 0.0439, 0.0007, 0.0005, and <0.0001, respectively (indicated by blue #). (C) SEM images of 2% MDI and 6% MDI after 35 days of degradation in media versus digestive media demonstrating that the 2% MDI scaffolds lost their structural integrity in both conditions, while the 6% MDI maintained architectural integrity in both conditions. (D) Side-view SEM of the final poly(glycerol sebacate) scaffold used in the remainder of the studies with the shown dimensions. This scaffold was bilayered with 6% MDI crosslinker used in the villus portion and 2% MDI crosslinker used in the base section. (E) Top-view SEM of the final scaffold chosen. (F) SEM cross-section of native porcine intestine for comparison. (G) En face SEM view of native porcine view demonstrating villi for comparison. MDI, 4,4′-methylenebis(phenyl isocyanate); SEM, scanning electron microscopy. Color images are available online.