Electrospinning of chitosan nanofibers: The favorable effect of metal ions

This study is aimed to assess the doping effects of monovalent, bivalent, and trivalent metal ions on the morphological appearance of the electrospun chitosan/poly(ethylene oxide) (PEO) blend nanofibers. Scanning electron micrographs confirmed that the presence of 0.4-1.6 wt% NaCl (or KCl) in the blend solutions produced nanofibers, accompanying re-crystallization of inorganic salts, while addition of appropriate amounts of CaCl2 or FeCl3 (∼0.8 wt%) resulted in beneficial effect on defect-free nanofibers. The Fourier transform infrared spectra and rheological analysis results implied that the addition of metal ions were favorable for decreasing the viscosity (45-60%) and hydrogen bonds of the blends. Moreover, the fabrication of metal-ion-modulated chitosan/PEO nanofibers would lend experience to processing binary, ternary or multinary biologically active trace elements-codoped nanofibers via electrospinning. This general electrospinning strategy, which involves doping of metal ions, may be versatile to modulate the fibrous structure and functionality of polymers.