Journal
BIOMATERIALS
Volume 30, Issue 28, Pages 4877-4888Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.biomaterials.2009.05.052
Keywords
pH-sensitive hydrogel; N-Palmitoyl chitosan; Viscoelastic property; Biocompatibility
Funding
- National Science Council [NSC 97-2120-M-007-001]
- NSRRC [2007-1-018-3]
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In-situ forming hydrogels triggered by environmental stimuli have emerged as a promising injectable strategy targeted for various biomedical applications. However, several drawbacks associated with temperature-stimulated hydrogels have been reported. Employing a hydrophobically-modified chitosan (N-palmitoyl chitosan, NPCS), we developed a pH-triggered hydrogel system which showed a rapid nanostructure transformation within a narrow pH range (pH 6.5-7.0). NPCS in an aqueous environment was found to be a shear-thinning fluid and exhibited an instant recovery of its elastic properties after shear thinning, thereby making it an injectable material. Additionally, aqueous NPCS, an associating polyelectrolyte, can be rapidly transformed into hydrogel triggered simply by its environmental pH through a proper balance between charge repulsion and hydrophobic interaction. This in-situ hydrogel system was shown to be nontoxic. Subcutaneous injection of aqueous NPCS (pH 6.5) into a rat model resulted in rapid formation of a massive hydrogel at the location of injection. The implanted hydrogel was found to be degradable and was associated with an initial macrophage response which decreased with time as the degradation proceeded. These results suggested that the developed NPCS hydrogel may be used as an injectable drug/cell delivery system. (C) 2009 Elsevier Ltd. All rights reserved.
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