Development of a biostable replacement for PEGDA hydrogels

The exceptional tunability of poly(ethylene glycol) (PEG) hydrogel chemical, mechanical, and biological properties enables their successful use in a wide range of biomedical applications. Although PEG diacrylate (PEGDA) hydrogels are often used as nondegradable controls in short-term in vitro studies, it is widely acknowledged that the hydrolytically labile esters formed upon acrylation of the PEG diol make them susceptible to slow degradation in vivo. A PEG hydrogel system that maintains the desirable properties of PEGDA while improving biostability would be valuable in preventing degradation-related failure of gel-based devices in long-term in vivo applications. To this end, PEG diacrylamide (PEGDAA) hydrogels were synthesized and characterized in quantitative comparison to traditional PEGDA hydrogels. It was found that PEGDAA hydrogel modulus and swelling can be tuned over a similar range and to comparable degrees as PEGDA hydrogels with changes in macromer molecular weight and concentration. Additionally, PEGDAA cytocompatibility, low cell adhesion, and capacity for incorporation of bioactivity were analogous to that of PEGDA. In vitro hydrolytic degradation studies showed that the amide-based PEGDAA had significantly increased biostability relative to PEGDA. Overall, these findings indicate that PEGDAA hydrogels are a suitable replacement for PEGDA hydrogels with enhanced hydrolytic resistance. In addition, these studies provide a quantitative measure of the hydrolytic degradation rate of PEGDA hydrogels which was previously lacking in the literature.