The effect of redox polymerisation on degradation and cell responses to poly (vinyl alcohol) hydrogels

Biocompatible, degradable hydrogel systems that can cure in situ following injection as a liquid are useful as a base for tissue engineering and drug delivery. In this study, poly (vinyl alcohol) (PVA) polymers were modified with degradable crosslinkers and formulated for either ultraviolet (UV) light initiation or chemical initiation using an oxidation/reduction (redox) curing method. A major objective was to compare the properties of degradable PVA hydrogels formed via two routes of curing. The effect of macromer concentration, degree of hydrolysis and functional group density on the degradation profiles was investigated. Also, since the hydrogels have been designed to be injected as a liquid for in situ curing, the effect of modified macromer solutions and degradation products on cell growth was investigated. Total degradation times ranged from approximately 20 days up to 120 days and increased in direct proportion with percent macromer. Initiation method (UV or redox) did not significantly impact on time for total degradation. While aqueous solutions of the modified macromer induced some cell growth inhibition, mainly associated with oxidative solutions, degradation products showed relatively low cell growth inhibition. Degradable PVA hydrogels tailored to produce networks with various degradation profiles can be cured by redox initiation and have potential as injectable polymers for soft-tissue engineering and drug delivery.