Influence of salt addition on polymer-free electrospinning of cyclodextrin nanofibers

Solution conductivity is one of the critical parameters affecting the electrospinning of polymer solutions as the jet formation is directly related to the movement of an electrically charged polymer solution to a grounded target. Hence, the solution conductivity has been studied for the electrospinning of various polymeric systems, but not yet for the electrospinning of polymer-free systems. In this regard, this study investigates the influence of solution conductivity on the electrospinning of CD molecules (i.e., hydroxypropyl (HP) modified β and γ -CDs) at various concentrations in the presence of quaternary ammonium salt (i.e., tetraethylammonium bromide, TEAB) from aqueous solutions. The addition of TEAB significantly boosted the conductivity of the CD solutions. It could lead to smaller particles at low CD concentrations because of electrohydrodynamic spraying, while the transformation from beaded-fibers to bead-free fibers was observed with an increase in the CD concentration. The salt addition decreased the fiber diameter and resulted in thinner nanofibers. Likewise, the incorporation of NaCl -used as an alternative to TEAB- caused thinning of the fibers due to enhanced solution conductivity. On the other hand, at higher salt contents, the fiber morphology was worsened for both CDs, leadings to beads on the fibers. Overall, this paper, for the first time, investigates the effect of solution conductivity of the electrospinning of a polymer-free system (i.e., CD), and the experimental findings show that increasing the solution conductivity with salt addition causes significant changes on the electrospinnability and fiber properties.