**4.1 Characterization of the encapsulation**

In order to clarify the encapsulation of Fol-8Col inside the fibers, two means were employed to characterize the encapsulation effect. FITC produces green fluorescence at 490nm. The fluorescence micrographs of NHS-Fluorescein labeled Fol-8Col/PLGA showed fluorescence emitting fibers (Figure 12), suggesting the homogeneous presence of Fol-8Col in the emulsion electrospun fibers. Consisting with the SEM images in Figure 1, bead defects of fibrous morphology were not observed.

In this study, poly (lactic-co-glycolic acid) (PLGA), a hydrophilic polymer with excellent biocompatibility and biodegradability which has been widely used in drug delivery and scaffold application, [61-63] was dissolved in chloroform/toluene (C/T) mixed solvent to form the oil phase of the emulsion. SPAN80 (Sorbitan Monooleate) was selected as a non-ionic surfactant widely used in pharmaceuticals and presumed to be non-toxic for biomedical use. The Fol-8Col dissolved in aqueous solution was emulsified with the PLGA oil phase to prepare the emulsion electrospinning dope. (Figure.11) The past work in emulsion electrospinning has been limited to relatively low water content of 4 vol.% (volume percent). [64] For some biomacromolecules that have comparatively low solubility in water, higher water content in the emulsions may be advantageous for their desirable encapsulation in fibers. The concept of using emulsion as a modulator in electrospinning was reported by J.C. Sy *et al*. [65] Here, we propose to introduce emulsions with high water content of 10 wt.% (weight percent). The distribution and inner layer structure of the encapsulated Fol-8Col was investigated. More‐ over, release profiles of encapsulated Fol-8Col from the fibrous mats and its short-term cell cytocompatibility to fibroblasts cell line L929 were tested for its potential application as a drug

release device as well as tissue engineering scaffold.

116 Advances in Nanofibers

**Figure 11.** Schematic of emulsion electrospinning.

**4.1 Characterization of the encapsulation**

In order to clarify the encapsulation of Fol-8Col inside the fibers, two means were employed to characterize the encapsulation effect. FITC produces green fluorescence at 490nm. The TEM observation was further conducted to identify the layer structure of emulsion electro‐ spun fibers in this study. The TEM image of Figure 13 suggested that the inner component Fol-8Col ofW/Oemulsion was properly wrapped in the centre ofresultant composite fiber. The boundary in the TEMimages reflects the difference of electron transmission ability between the core (Fol-8Col) and sheath (PLGA). However, a slanted portion of boundary can be observed which is associated with the miscibility of amphiphilic surfactant (SPAN80) molecule.

**Figure 12.** Fluorescence microphotograph of Fol-8Col/PLGA fibers electrospun with Fol-8Col (5 wt% aqueous con‐ tent), a C/T weight ratio of 75/25, and 10wt% PLGA.

**Figure 13.** TEM images of Fol-8Col/PLGA fibers electrospun from Fol-8Col [5 (I) and 10wt%(II) aqueous content], with a C/T weight ratio of 75/25 and a PLGA concentration of10 wt%.
