Mechanical and Chemical Analysis of Gelatin-Based Hydrogel Degradation

Abstract

The interrelated effect of environmental pH and temperature, gelatin backbone modification and content on the tensile and degradative property of interpenetrating networks (IPNs) containing gelatin and poly(ethylene glycol) diacrylate (PEGdA) was examined. Either increasing the PEGdA content or modifying the gelatin backbone with PEG-monoacetate ester and/or polyanions decreased the IPN elasticity at ambient room temperature (rt). Under an aqueous environment of varying pH levels and elevated temperature, the degradation of IPN tensile properties was further accelerated. IPNs showed an enhanced elasticity and strength when compared to glutaraldehyde-fixed gelatin hydrogels. Under an aqueous condition, IPNs showed a wider range of degradation products than hydrogels cross-linked with glutaraldehyde, as characterized with gel permeation chromatography. The nature of IPN degradation products was independent of the type of gelatin backbone modification. The presence of loaded drug, chlorohexidine digluconate, which was found to interact with PEG-monoacetate esters of the modified gelatin backbone, resulted in unique degradation products. The tensile and chemical degradation of IPNs is a complex interrelationship of the environmental condition, time, and material modification.