Buwalda S.J. - In Situ Forming Poly(ethylene glycol)- Poly( L -lactide) Hydrogels via Michael Addition: Mechanical Properties, Degradation, and Protein Release

Sytze J. Buwalda, Pieter J. Dijkstra,* Jan Feijen

Macromolecular Chemistry and Physics 2012

Abstract

Chemically crosslinked hydrogels are prepared at remarkably low macromonomer concentrations from 8-arm poly(ethylene glycol)-poly( L -lactide) star block copolymers bearing acrylate end groups (PEG-(PLLA n ) 8 -AC, n = 4 or 12) and multifunctional PEG thiols (PEG-(SH) n , n = 2, 4, or 8) through a Michael-type addition reaction. Hydrogels are obtained within 1 min after mixing PEG-(PLLA 4 ) 8 -AC and PEG-(SH) 8 in phosphate buffered saline, quickly reaching a high storage modulus of 17 kPa. Lysozyme and albumin are released for 4 weeks from PEG-(PLLA 12 ) 8 -AC/PEG-(SH) 8 hydrogels. Lysozyme release from PEG-(PLLA 12 ) 8 -AC/PEG-(SH) 2 and PEG-(PLLA 12 ) 8 -AC/PEG-(SH) 4 hydrogels is significantly faster with complete release in 3 and 12 d, respectively, as a result of a combination of degradation and diffusion.