Chitosan (CS), the deacetylated form of chitin, the second most abundant, natural polysaccharide, is attractive for applications in the biomedical field because of its biocompatibility and resorption rates, which are higher than chitin. Crosslinking improves chemical and mechanical stability of CS. Here, we report the successful utilization of a new set of crosslinkers for electrospun CS. Genipin, hexamethylene-1,6-diaminocarboxysulphonate (HDACS) and epichlorohydrin (ECH) have not been previously explored for crosslinking of electrospun CS. In this first part of a two-part publication, we report the morphology, determined by field emission scanning electron microscopy (FESEM), and chemical interactions, determined by Fourier transform infrared microscopy, respectively. FESEM revealed that CS could successfully be electrospun from trifluoroacetic acid with genipin, HDACS and ECH added to the solution. Diameters were 267 + 199 nm, 644 + 359 nm and 896 + 435 nm for CS -genipin, CS -HDACS and CS -ECH, respectively. Short-(15 min) and long-term (72 h) dissolution tests (T 600 ) were performed in acidic, neutral and basic pHs (3, 7 and 12). Post-spinning activation by heat and base to enhance crosslinking of CS-HDACS and CS-ECH decreased the fibre diameters and improved the stability. In the second part of this publication, we report the mechanical properties of the fibres.

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Electrospinning is an inexpensive and simple method of producing non-woven fiber mats. Electrostatic forces are employed to produce the mats, which intrinsically have larger specific surface to volume ratio and smaller pores than traditional fibers. Fibrous mats are typically used in a wide variety of industries such as filter media, tissue engineering, and sensors. Chitosan, the N-deacetylated derivative of chitin, is environmentally friendly, non-toxic, biodegradable, and anti-bacterial. However, due to chitosan’s solubility in aqueous acids, it is electrospun using trifluoroacetic acid (TFA). Modified chitosans, such as carboxymethylchitosan, are currently under investigation as a means of creating designed nanofibrous mats with specific chemistries. However, typically an entirely new set of electrospinning conditions has to be developed for each novel chemistry due to differences in solubility and viscosity. In the present study, we have electrospun chitosan mats and post-processed the fibers. Two different post-processing conditions were employed. One post-production procedure, featuring vapor-phase glutaraldehyde, effectively crosslinks the fiber mats utilizing a Schiff base imine functionality. In another post-processing procedure, the as-spun mats are solution-phase post-processed by chemically functionalizing the mats with cyano, carboxylic acids and thiol groups. While both methods maintained fiber shape and characteristics, there is a definite increase in fiber diameters due to processing. FTIR, NMR, SEM and tensile testing have been performed on the pre- or post-processed fiber mats. Investigations into the percent modification are currently underway.