Electrospinning of nanofibers from non-polymeric systems: Electrospun nanofibers from native cyclodextrins

Electrospinning of nanofibers from non-polymeric systems is rather challenging, yet in this study, we have successfully performed electrospinning of nanofibers from two of the native cyclodextrins (CDs); alpha-CD and beta-CD. Electrospinning was carried out for highly concentrated solutions of a-CD (120% up to 160%, w/v) and beta-CD (120% up to 150%, w/v) in basic aqueous system. At optimal concentration level, the electrospinning of CD solutions yielded bead-free uniform CD nanofibers without using carrier polymeric matrix. Similar to polymeric systems, the electrospinning of CD solutions resulted in different mor-phologies and average fiber diameters depending on the CD type and CD concentration. The dynamic light scattering (DLS) and rheology measurements were performed in order to examine the electrospin-nability of CD solutions. The existence of CD aggregates via hydrogen bonding and very high solution viscosity and viscoelastic solid-like behavior of CD solutions were found to be the key factors for obtaining bead-free nanofibers from CDs. The addition of urea disrupted CD aggregates and lowered the viscosity significantly, and therefore, the urea-added CD solutions yielded beaded fibers and/or beads. Although the as-received CDs in powder form are crystalline, the structural analyses by XRD and HR-TEM indicated that electrospun CD nanofibers have amorphous characteristic without showing any particular orientation or crystalline aggregation of CD molecules. (C) 2013 Elsevier Inc. All rights reserved.