Synthesis and viscoelastic characterization of novel hydrogels generated via photopolymerization of 1,2-epoxy-5-hexene modified poly(vinyl alcohol) for use in tissue replacement.

Hydrogels have been proposed as candidates for tissue replacement; however, current systems are often highly susceptible to hydrolytic degradation and have not been shown to mimic the viscoelastic behavior of the native tissue when subjected to dynamic loading conditions. In the present work, 1,2-epoxy-5-hexene modified poly(vinyl alcohol) was crosslinked via photopolymerization to generate non-degradable hydrogels with mechanical properties and network characteristics that could be modulated through variation in the type and percentage of a monomeric additive. Complex shear moduli obtained from dynamic frequency sweeps in torsional shear were used to exemplify the differences in the viscoelastic behavior of the materials, and the corresponding changes in crosslink density were determined by rubber elasticity theory. Hydrolysis resistance was assessed by monitoring variations in the moduli of hydrogels submerged in Hank's balanced salt solution for progressively longer periods of time. Over the time-frame of the experiment, no change in the viscoelastic behavior was observed. Direct contact assays and elution tests were used to demonstrate that the system was non-cytotoxic. This study represents a successful attempt to generate a non-degradable hydrogel system with viscoelastic behavior that can be readily modulated to match that of soft biological tissues for use in tissue replacement.