A cellular automaton simulation of the degradation of porous polylactide scaffold: I. Effect of porosity

Abstract

A cellular automaton method that includes a fabricating model for solvent casting/porogen leaching and a multiple-particle random walk model for oligomer molecular diffusion was used to simulate degradation behaviors and their dependence on the initial porosities (80%, 90% and 95%) of porous polylactide (PLA) scaffolds. Changes in the mass loss, molecular weight, numbers of PLA chains and ester groups, oligomer molecules release and average degradation rate with degradation time were investigated. The results show that during degradation, higher initial porosity resulted in greater molecular weight and a higher average number of ester groups and less mass loss, a lower number of oligomer molecules being released and a lower ratio of oligomer molecules remaining in the scaffold to those in the whole model. The average degradation rate and average number of PLA chains initially changed in direct proportion to the initial porosity, but there was an inverse change later in the degradation. In addition, no hollow structures were found in any of the scaffolds during the degradation, which indicates there was no dramatic autocatalytic phenomenon such as that seen for massive solid structures such as a plate in the porous PLA scaffold. The above simulated results are consistent with recent experimental reports, suggesting our simulating method has potential application in studying the degradation behaviors of porous scaffolds for tissue engineering.