Electrospun gelatin fibers: Effect of solvent system on morphology and fiber diameters

Gelatin, a naturally-occurring biopolymer, was electrospun in the present contribution. Gelatin solutions were prepared in either single solvent system [i.e., glacial acetic acid (AA)] or mixed solvent systems [i.e., AA/2,2,2-trifluoroethanol (TFE), AA/dimethyl sulfoxide (DMSO), AA/ethylene glycol (EG), and AA/formamide (F)]. The electrospinning was carried out under a fixed electrostatic field strength of 7.5 kV/7.5 cm and the polarity of the emitting electrode was positive. The effects of these solvent systems on morphology and/or size of the electrospun materials were observed by scanning electron microscopy (SEM). Electrospinning of 15-29% w/v gelatin solutions in AA produced beads, beaded fibers, and smooth fibers, depending on the concentration range. Only smooth fibers were observed at the concentration range of 21-29% w/v, with their average diameter ranging between 214 and 839 nm. The addition of TFE as a co-solvent or another modifying liquid of DMSO, EG, or F helped improve the electrospinnability of the resulting gelatin solution. Among the three modifying liquids, DMSO and EG contributed to the formation of smooth gelatin fibers with reduced diameters when compared with those obtained from the solution in pure AA.