Preparation of Pure and Stable Chitosan Nanofibers by Electrospinning in the Presence of Poly(ethylene oxide)

Abstract

Electrospinning was employed to obtain chitosan nanofibers from blends of chitosans (CS) and poly(ethylene oxide) (PEO). Blends of chitosan (MW (weight-average molecular weight) = 102 kg/mol) and PEO (M (molecular weight) = 1000 kg/mol) were selected to optimize the electrospinning process parameters. The PEO powder was solubilized into chitosan solution at different weight ratios in 0.5 M acetic acid. The physicochemical changes of the nanofibers were determined by scanning electron microscopy (SEM), swelling capacity, and nuclear magnetic resonance (NMR) spectroscopy. For stabilization, the produced nanofibers were neutralized with K2CO3 in water or 70% ethanol/30% water as solvent. Subsequently, repeated washings with pure water were performed to extract PEO, potassium acetate and carbonate salts formed in the course of chitosan nanofiber purification. The increase of PEO content in the blend from 20 to 40 w% exhibited bead-free fibers with average diameters 85 ± 19 and 147 ± 28 nm, respectively. Their NMR analysis proved that PEO and the salts were nearly completely removed from the nanostructure of chitosan, demonstrating that the adopted strategy is successful for producing pure chitosan nanofibers. In addition, the nanofibers obtained after neutralization in ethanol-aqueous solution has better structural stability, at least for six months in aqueous solutions (phosphate buffer (PBS) or water).

Nanofibrous Scaffolds for Skin Tissue Engineering and Wound Healing Based on Nature-Derived Polymers

“…Electrospinning of pure chitosan has very low productivity because it requires very concentrated polymeric solutions [141]. Therefore, for creation of nanofibrous scaffolds for skin tissue engineering, chitosan has been mixed with other natural or synthetic polymers, such as collagen [142], gelatin [143], keratin [116], cellulose [144], pectin [54,55], silk fibroin [69], PHBV [145], PCL [142], PLA [146], PLGA [147], PEO, [148], and also with PVA, which was used in our studies (Figure 3). Chitosan has also been mixed with various nanoparticles, such as halloysite nanotubes [149], graphene oxide [150] or nanodiamonds [144].…”

Biomaterials from Chitosan Processed by Electrospinning

“…After electrospinning, nanofibers under protonated form of chitosan are made of chitosan/PEO blends. Pure chitosan nanofibers are recovered by immersion in ethanol/water 70/30 (v/v) containing potassium carbonate (0.2 M) and washing in water [17,18]. An example of the nanofibers obtained is given in figure 4.…”

Trends in Tissue Regeneration: Bio-Nanomaterials

“…Electro spinning technique can produce nano-sized fibers from different sources, such as polymers, biocompatible systems, sol-gel, and nanocomposite materials. This technique generates three-dimensional porous fibers with high electrostatic attraction, associated with their high surface area/aspect ratio [47]. In this regard, this technique works from a solution (polymer, nanocomposite, and others) passed through a syringe, ending from a Taylor cone to control the efflux.…”

“…A voltage source creates a drop and is collected at different distances to create variable morphology fibers. The surface tension produced between the collector and the needle is created by the electrostatic forces of the fibers [47].…”