Rapidly in situ forming biodegradable robust hydrogels by combining stereocomplexation and photopolymerization

C. Hiemstra, W. Zhou, Zhiyuan Zhong, Marielle Wouters, Jan Feijen

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Our previous studies have shown that stereocomplexed hydrogels can be rapidly formed in vitro as well as in vivo upon mixing aqueous solutions of eight-arm poly(ethylene glycol)−poly(l-lactide) (PEG−PLLA) and poly(ethylene glycol)−poly(d-lactide) (PEG−PDLA) star block copolymers. In this study, stereocomplexation and photopolymerization are combined to yield rapidly in situ forming robust hydrogels. Two types of methacrylate-functionalized PEG−PLLA and PEG−PDLA star block copolymers, PEG−PLLA−MA and PEG−PDLA−MA, which have methacrylate groups at the PLA chain ends and PEG−MA/PLLA and PEG−MA/PDLA, which have methacrylate groups at the PEG chain ends, were designed and prepared. Results showed that stereocomplexed hydrogels could be rapidly formed (within 1−2 min) in a polymer concentration range of 12.5−17.5% (w/v), in which the methacrylate group hardly interfered with the stereocomplexation. When subsequently photopolymerized, these hydrogels showed largely increased storage moduli as compared to the corresponding hydrogels that were cross-linked by stereocomplexation or photopolymerization only. Interestingly, the storage modulus of stereocomplexed−photopolymerized PEG−PLA−MA hydrogels increased linearly with increasing stereocomplexation equilibration time prior to photopolymerization (from ca. 6 to 32 kPa), indicating that stereocomplexation aids in photopolymerization. Importantly, photopolymerization of stereocomplexed hydrogels could take place at very low initiator concentrations (0.003 wt %). Swelling/degradation studies showed that combining stereocomplexation and photopolymerization yielded hydrogels with prolonged degradation times as compared to corresponding hydrogels cross-linked by photopolymerization only (3 vs 1.5 weeks). Stereocomplexed−photopolymerized PEG−MA/PLA hydrogels degraded much slower than corresponding PEG−PLA−MA hydrogels, with degradation times ranging from 7 to more than 16 weeks. Therefore, combining stereocomplexation and photopolymerization is a novel approach to obtain rapidly in situ forming robust hydrogels.
Original languageUndefined
Pages (from-to)9918-9926
JournalJournal of the American Chemical Society
Issue number32
Publication statusPublished - 2007


  • METIS-246216
  • IR-60297

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