Table 2 | List of studies using co-axial electrospinning

Sheath/core polymers	Solvents		Fiber dia (nm) Total (core)	Objective of the study	Reference
Sheath/core polymers	Sheath	Core	Fiber dia (nm) Total (core)	Objective of the study	Reference
PEO/PEO PEO/PSU	Water + ethanol Water + ethanol	Water + ethanol Chloroform	3000 (2000) 60 (40)	To demonstrate the feasibility of the co-axial electrospinning process	Sun et al. 2003 [21]
PCL/Gelatin	TFE	TFE	100 to 300 (<100)	To demonstrate core-sheath fiber formation using bio-degradable materials	Zhang et al. 2004 [8]
PCL/Gelatin	TFE	TFE	200 to 500 (61 to 180)	To improve mechanical performance of the nano fiber mat	Huang et al. 2005 [22]
Collagen/PCL	HFIP	TFE	385 (321)	To improve surface bio-compatibility of the nano fibers for tissue engineering application	Zhang et al. 2005 [10]
PVP/PLA	DMF + ethanol	DMF + acetone	400 to 500 (200 to 300)	To prepare biodegradable composite nanofiber structure for possible controlled particle release application (e.g. drug delivery)	Sun et al. 2006 [39]

Table 2: List of studies using co-axial electrospinning to prepare core-shell nanofibers.