Synthesis and aggregation behavior of chitooligosaccharide‐based biodegradable graft copolymers

Abstract

A series of novel “jellyfish‐like” graft copolymers with chitooligosaccharide (COS) as shorter backbone and poly(ε‐caprolactone) as longer branches were synthesized using ring‐opening polymerization of ε‐caprolactone via a protection‐polymerization‐deprotection procedure with trimethylsilylchitooligosaccharide as intermediate and triethylaluminum as catalyst precursor. The obtained chitooligosaccharide‐graft‐poly(ε‐caprolactone) polymers possess amphiphilic structure with hydrophilic COS backbone and hydrophobic polycaprolactone branches. Because of this unique “jellyfish‐like” structure, these graft copolymers could self‐assemble to form various morphologies of aggregates in a mixture solution of water and tetrahydrofuran. The transmission electron microscopy studies revealed that the formed aggregates exhibited necklace‐like, flower‐like onion vesicle, and tubular morphologies. It is found that the hydrogen‐bonding formed by the hydroxyl and amino groups remained on the COS backbone played an important role during the aggregation of these graft copolymers, and their morphologies were changed with the varying length of poly (ε‐caprolactone) branches, the concentration of the graft copolymer, and the self‐assembly process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4889–4904, 2008

Synthesis of chitosan‐based thermo‐ and pH‐responsive porous nanoparticles by temperature‐dependent self‐assembly method and their application in drug release

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Deletion in the tyrosine hydroxylase gene in a patient with a mild phenotype

“…In light of their hollow structure, polymeric hollow particles have great potential for the encapsulation of large quantities of guest molecules and release them at a later stage in a well‐controlled manner 5, 6. Several different methods, such as the layer‐by‐layer deposition of polyelectrolyte on a template core,7–12 polymerizing monomers in lipid vesicles,13, 14 self‐assembly of block copolymers in an appropriate solvent,15–19 and emulsion (or miniemulsion) polymerization,20, 21 have been used to prepare polymeric hollow particles. For the biomedical applications, it would be better that polymeric hollow particles also have properties of biocompatibility, biodegradability, and low cytotoxicity.…”

Synthesis, characterization and micellization of heterograft copolymers based on phosphoester functionalized macromonomers via “grafting through” method

“…39,40 Gao et al synthesized branched copolymers with ''jellyfish-like'' structure, which could form various aggregates with different morphologies, including necklace-like, flower-like onion vesicle, and fiber-like. 7 Zhang 9 and Feng 10 both reported the formation of vesicle structures of the amphiphilic graft copolymers. Other morphologies such as spherical 12,31,41 and Janus-type 42 micelles have also been reported.…”

“…Other morphologies such as spherical 12,31,41 and Janus-type 42 micelles have also been reported. Typical hydrophobic components of these polymers include poly(e-caprolactone) (PCL) 7,12,31 and polystyrene. 41 Poly(ethylene glycol) (PEG) is one of the most widely used hydrophilic components due to its highly hydrophilic and biocompatible properties.…”