A smart methodology to fabricate electrospun chitosan nanofiber matrices for regenerative engineering applications

Abstract

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·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. Copyright © 2014 John Wiley & Sons, Ltd.

Neural tissue engineering: nanofiber‐hydrogel based composite scaffolds

“…Fixed samples were washed with distilled water and dried under vacuum and kept desiccated. Scaffold surfaces were sputter coated with Au/Pd using a Hummer V sputtering system (Technics Inc., Baltimore, MD) prior to imaging …”

“…Electrospun nanofiber matrices comprised of both natural and synthetic polymers have been developed for a variety of tissue engineering applications . Electrospun polycaprolactone (PCL) fiber matrices present mechanical properties ideal for soft tissue regeneration, but lack the optimal hydrophilic features to promote cell adhesion .…”

Bioactive Applications for Electrospun Fibers

“…Mats produced using high molecular weight chitosan are known to improve mechanical stability compared with low molecular weight chitosan and its blends with other synthetic polymers, but the higher the molecular weight, the more difficult it is to electrospin. Nada et al 75 reported a modification in the methodology of electrospinning chitosan that allows processing high molecular weight chitosan without additives or blends at much higher concentrations than before. It involves a chitosan derivative, namely 2-nitrobenzyl-chitosan, prepared by reacting chitosan with 2-nitrobenzaldehyde in aqueous solution in order to produce a Schiff base, 2-nitrobenzaldehyde, which protects the amine of chitosan and yields a derivative soluble in trifluoroacetic acid.…”

Liposomal Microencapsulation of Rodent-repelling Agents onto Jute Burlaps: Assessment of Cytotoxicity and Rat Behavioral Test

“…This was done according to the procedure described by (Moustafa et al, 2014;Nada et al, 2015)with slight modification as described in details by (El-Menshawi et al, 2010;Mohamed et al, Accepted 2016). In typical procedure, cells were maintained in Dulbecco's modified eagle medium (DMEM):F12 Medium (nutrient mixture)/10% fetal bovine serum (FBS) and were incubated at 37°C in 5% CO 2 and 95% humidity.…”