Electrospinning of Chitosan-Based Nanocomposites Reinforced with Biobased Nanocrystals for Biomedical Applications

Abstract:

In the present study, chitosan was chosen as an excellent material for wound dressing application due to its non-toxicity, biocompatibility and its ability to stimulate the immune system, promote cellular growth, and control bacterial proliferation. Chitosan-based nanocomposite fibrous mats were successfully produced by using electrospinning technique. Chitosan–poly(ethylene oxide) blend at 1:1 mass ratio was used as matrix, and cellulose or chitin nanocrystals at 50 wt% content were used as reinforcing phase. Aqueous solution of 50 wt% acetic acid was chosen as electrospinning solvent, and the final solute concentration of the electrospinning solutions was 3 wt%. Preliminary experiments were performed in order to determine the optimum processing parameters that could generate defect-free fibers. The morphological, thermal and physicochemical properties of the as spun mats were investigated by optical microscopy, SEM, TGA, DSC, porosimetry and water vapor transmission. The morphological study showed that the inclusion of nanocrystals decreased the average fiber diameter from 308 ± 31 nm to 138 ± 25 nm for cellulose nanocrystals, and to 213 ± 28 nm for chitin nanocrystals. The thermal analysis indicated that every electrospun mats had the thermal stability required for use as wound dressing, except the mat reinforced with cellulose nanocrystals, and the mat reinforced with chitin nanocrystals exhibited the highest thermal stability. The surface area, average pore size and water vapor transmission were similar from one sample to another, and were considered as beneficial for wound healing. The nanofibrous mats reinforced with chitin nanocrystals were further crosslinked by using genipin aqueous solution for 4, 8 and 16 hours in order to enhance the mechanical properties. Uniaxial tensile testing and scanning electron microscopy were performed to control the efficiency of crosslinking. The results suggested that the mechanical strength significantly increased as a function of the crosslinking exposure time, which confirmed that crosslinking was efficiently achieved. A similar trend was observed when the nanocrystals were added to the chitosan-based matrix. The nanocomposite mat reinforced with chitin nanocrystals and crosslinked for 16 hours had a tensile strength of 64.9 MPa and an elastic modulus of 10.2 GPa, and was considered as the best candidate for wound dressing application.