Dynamics of Biodegradation

Biodegradable polymers are widely used in drug delivery and tissue engineering. However, direct experimental observation of the degradation process of such polymers is limited. To address this issue, we have developed a coarse-grained model to mimic degradation dynamics of L-valine and L-phenylalanine based poly(ester urea)s (PEUs) in vitro. Simulations show that the rates of hydrolysis and chain diffusion control the degradation process. In particular, it is found that PEU’s experience a combination of surface and bulk erosions, which both contribute to the degradation of the material. By tuning the reaction parameters in our simulations, we determine the crossover between degradation-controlled and swelling-controlled regimes. Using these results, we established a general framework for modeling competition between degradation and swelling-controlled mechanisms in biodegradable materials. To test model predictions and to map coarse-grained parameters, we compare the time evolution of the molecular weight distributions of the polymer chains obtained in simulations with those obtained experimentally from size-exclusion chromatography.