Figure 2.

SEM images of the drug-free and drug-loaded zein (Z) fibers, magnification ×2000. Compositions of the core and shell solutions are indicated on the vertical and horizontal panes, respectively. The mean diameter size with standard deviation of the fibers is given in the white box in the upper right corner. (a,c) No fibers were produced when absolute ethanol (E) was used as shell solution with zein or zein + stearic acid (SA) as a core. (b) Fibers were produced with E as a shell solution only when polyethylene oxide (PEO) was present in the core, sample (Z+PEO)E. (d–f) PEO coated fibers. Tubular fibers were obtained when PEO was present both in the core and in the shell as in sample (Z+PEO)PEO. (g–i) Tetracycline hydrochloride (T)-loaded fibers. Incorporation of the drug changed the morphology towards more ribbon-shaped fibers, which led to an increase in the diameter distribution. Nomenclature of the samples: composition of the core is shown in brackets, while the shell polymer or solvent is specified outside of the brackets.