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摘要
The electrospinning of chitosan remains challenging due to its rigid crystalline structure, insufficient viscosity, and limited solubility in common organic solvents. This work presents a "smart" chitosan modification that allows electrospinning irrespective of molecular weight or deacetylation value and without blending with synthetic polymers. A novel derivative, namely 2-nitrobenzyl-chitosan (NB), at various molar compositions of chitosan:2-nitrobenzaldehyde (1:1 (NB-1), 1:0.5 (NB-2), 1:0.25 (NB-3)) was synthesized by the reaction between amino groups of chitosan and aldehyde groups of 2-nitrobenzaldehyde. In this Schiff base, 2-nitrobenzaldehyde protects the amine functionalities of chitosan and improves its solubility in trifluoroacetic acid. 2-nitrobenzaldehyde is a photoactivatable-caged compound that cleaves off from iminochitosan on ultraviolet exposure yielding neat chitosan. Derivatives showed improved solubility in trifluoroacetic acid and dynamic viscosities in the range of 1.34 +/- 0.7 to 12 +/- 0.5 Pa center dot s based on the degree of substitution and concentration. Electrospinning conditions were optimized to produce bead free nanofibers in the range of 100-600 nm, and concentrations beyond 12% (wt/v) for NB-1 and NB-2, and 15% (wt/v) for NB-3 were suitable. Photolysis did not alter fiber morphology; however, regenerated chitosan matrices were soluble in culture media presumably due to the presence of 2-nitrosobenzoic acid in trace amounts. Human skin fibroblasts exhibited excellent (>90%) cytocompatibility on treatment with polymer extractions from cross-linked regenerated chitosan matrices prepared to the ISO standard. Newly synthesized iminochitosan derivatives were very effective against microorganisms including bacteria (Gram-positive and Gram-negative), fungi, and yeast. These fiber matrices may serve as scaffolds for a variety of tissue healing and factor delivery applications.
- 出版日期2014-5
