Degradable, click poly(vinyl alcohol) hydrogels: characterization of degradation and cellular compatibility

The aim of this research was to understand the influence of functional group density on degradation and cell survival within injectable poly(vinyl alcohol) (PVA) hydrogels crosslinked through hydrazone bonds. For this purpose, PVA was modified with aldehyde and hydrazide functional groups. The click reaction between these two macromers, performed under physiologic conditions, led to hydrogel formation in less than 3 min. The influence of the crosslinking density on the gelation time, volumetric swelling ratio and mass loss of the hydrogels was investigated. These systems were slowly degradable as they maintained their gel-like state for more than 120 days. However, these networks also exhibited unusual degradation behaviour that could be the result of a breaking-forming bond phenomenon, attributable to the reversible nature of the hydrazone bond. This study also demonstrated that these networks maintained their mechanical strength while degrading, and cell encapsulation revealed the cytocompatibility of these systems.