Electrospun nanofibrous scaffolds providing local delivery of vascular endothelial growth factor (VEGF) have distinctive advantages for vascular tissue engineering. However, more than 90% of VEGF were normally released from scaffolds formed by conventional positive-voltage emulsion electrospinning (PVEES) within the initial 3 days. VEGF molecules bear positive charge. In this investigation, emulsion electrospinning using power supplies of different polarities was studied for producing scaffolds bearing specific electric charge. VEGF-containing poly(lactic-co-glycolic acid) scaffolds with initial potential of -87 and -202 V were formed by negative-voltage emulsion electrospinning (NVEES) at -10 and -20 kV, respectively, which enabled steady and sustained release up to 18 days, exhibiting effective modulation for VEGF release. Compared to VEGF-containing scaffolds formed by PVEES, NVEES-formed scaffolds showed superior performance in promoting endothelial cell functions. (C) 2017 Elsevier B.V. All rights reserved.