Influence of Amide versus Ester Linkages on the Properties of Eight-Armed PEG-PLA Star Block Copolymer Hydrogels

Water-soluble eight-armed poly(ethylene glycol)-poly(l-lactide) star block copolymers linked by an amide or ester group between the PEG core and the PLA blocks (PEG-(NHCO)-(PLA)8 and PEG-(OCO)-(PLA)8) were synthesized by the stannous octoate catalyzed ring-opening polymerization of l-lactide using a...

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Bibliographic Details
Published in:Biomacromolecules 2010-01, Vol.11 (1), p.224-232
Main Authors: Buwalda, Sytze J, Dijkstra, Pieter J, Calucci, Lucia, Forte, Claudia, Feijen, Jan
Format: Article
Language:English
Subjects:
Amides - chemistry
Applied sciences
Biocompatible Materials
Esters - chemistry
Exact sciences and technology
Hydrogels - chemistry
Magnetic Resonance Spectroscopy
Organic polymers
Physicochemistry of polymers
Polyesters - chemistry
Polyethylene Glycols - chemistry
Polymerization
Polymers - chemistry
Preparation, kinetics, thermodynamics, mechanism and catalysts
Rheology
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Summary:Water-soluble eight-armed poly(ethylene glycol)-poly(l-lactide) star block copolymers linked by an amide or ester group between the PEG core and the PLA blocks (PEG-(NHCO)-(PLA)8 and PEG-(OCO)-(PLA)8) were synthesized by the stannous octoate catalyzed ring-opening polymerization of l-lactide using an amine- or hydroxyl-terminated eight-armed star PEG. At concentrations above the critical gel concentration, thermosensitive hydrogels were obtained, showing a reversible single gel-to-sol transition. At similar composition PEG-(NHCO)-(PLA)8 hydrogels were formed at significantly lower polymer concentrations and had higher storage moduli. Whereas the hydrolytic degradation/dissolution of the PEG-(OCO)-(PLA)8 takes place by preferential hydrolysis of the ester bond between the PEG and PLA block, the PEG-(NHCO)-(PLA)8 hydrogels degrade through hydrolysis of ester bonds in the PLA main chain. Because of their relatively good mechanical properties and slow degradation in vitro, PEG-(NHCO)-(PLA)8 hydrogels are interesting materials for biomedical applications such as controlled drug delivery systems and matrices for tissue engineering.
ISSN:1525-7797
1526-4602
DOI:10.1021/bm901080d