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. Author manuscript; available in PMC: 2015 Apr 21.
Published in final edited form as: J Mater Chem B. 2014;2(34):5511–5521. doi: 10.1039/c4tb00496e

Fig. 3. Multimode hydrogel degradation.

Fig. 3

Schematic of the click bond cleavage and thiol exchange reaction of thioether succinimide linkages under a glutathione (GSH) reducing microenvironment and by ester hydrolysis. The D1E hydrogels can only undergo degradation by ester hydrolysis. D2ER hydrogels can undergo degradation by ester hydrolysis and by thiol exchange reactions, owing to the presence of arylthiol-based thioether succinimide linkages. Owing to the lack of degradable functional groups, control hydrogels do not degrade in aqueous reducing microenvironments. The rate and extent of the click bond cleavage depends on the Michael donor reactivity and thiol pKa.