Theoretical Verification of Surface Cross-Linking as an Effective Method To Reduce Initial Burst Release from Swellable Hydrogels

Abstract

In this paper, we extend a mathematical model previously proposed for drug release from homogeneous swellable hydrogels to surface cross-linked hydrogels. This new model predicts the simultaneous water uptake into and drug diffusion from a cross-linked hydrogel with a bulk inner core surrounded by a highly cross-linked surface layer. The model verifies our experimental work to show that the treatment of surface cross-linking can be used to reduce the initial burst observed in homogeneous poly(vinyl alcohol) hydrogels and achieve near zero-order release. In the model, the parameter that has the greatest impact on reduced burst release is the water partition coefficient between the surface cross-linked and bulk layers.