Stochastic Lattice-Based Modeling of Macromolecule Release from Degradable Hydrogel.

A three-dimensional lattice-based model has been developed to describe the release of a macromolecular drug encapsulated in a degradable hydrogel. The degradation-induced network heterogeneity is considered by assigning varying diffusion coefficients to the lattice sites based on the fitted exponential node-diffusivity relationship. As time passes, due to the degradation of crosslink nodes, diffusivity values in lattice sites progress to higher values. To overcome the size limitation of the computational model and to compare it with experimental data, a scaling ratio based on the random walk equation is developed. The model was able to describe the experimental release data from chemically crosslinked dextran hydrogels. The results showed that the effect of the initial network and the chemistry of crosslink nodes (hydrolysis rate) on the drug release profile cannot be decoupled.