In vitro degradation kinetics of PTK-UR scaffolds. Data are presented as mean ± standard error with n = 3. (A) Long-term stability of PTK-UR scaffolds incubated in PBS. (B) Percent degradation of PTK-UR scaffolds incubated in oxidative medium (20% H2O2 in 0.1M CoCl2) as a function of PTK composition. Dashed lines represent model-generated curves for first-order degradation kinetics, *p < 0.05. Percent mass remaining of (C) 100% MEE-PTK-UR, (D) 50% MEE-PTK-UR, and (E) 0% MEE-PTK-UR scaffolds incubated in oxidative media containing 20%, 2%, and 0.2% H2O2. (F) Degradation constants used to generate the best-fit curves in (B-E), as determined by non-linear regression analysis. The PTK-UR but not the PEUR scaffolds exhibited H2O2 dose-dependent degradation.