Synthesis of a New PHEMA/PEO Enzymatically Biodegradable Hydrogel

We report the synthesis of a new enzymatically degradable gel based on PHEMA and PEO crosslinking macromonomer. The crosslinker contains the tripeptide sequence Gly‐Gly‐Leu, which is a substrate for proteases such as subtilisin or chymotrypsin. The crosslinker was obtained by the coupling reaction of succinyl‐glycyl‐glycyl‐leucine with 2‐aminoethyl‐terminated PEO chains ($\overline M _{\rm w}$ = 3 400) and subsequent esterification of the hydroxyl endgroup with methacryloyl chloride. It was characterized by SEC and 1H NMR. Enzymatic cleavage of the crosslinking macromonomer was showed by SEC. The macromonomer was copolymerized with HEMA to yield hydrogel that is stable in a physiological buffer. Enzymatic assay showed that this gel is degraded in the presence of a bacterial protease (subtilisin). The degradation is complete within 50 d at 37 °C. This new gel is a good candidate for drug‐delivery systems where the release can be triggered by the presence of bacterial proteases. PHEMA crosslinked with MA‐PEG‐SucGGL‐PEO‐MA and its degradation by subtilisin.