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Positive voltage electrospinning (PVES) has been mainly used for forming fibrous polymer scaffolds for different applications including tissue engineering. There is virtually no report on negative voltage electrospinning (NVES) of tissue engineering scaffolds. In this study, NVES of four biopolymers, namely, gelatin, chitosan, poly(lactic-co-glycolic acid) (PLGA), and polybutylene terephthalate (PBT), to form nanofibrous membranes was systematically investigated. For comparisons, PVES of these polymers was also conducted. It was found that chitosan fibers could not be produced using NVES. Under NVES or PVES, the fiber diameter of electrospun scaffolds generally increased with increasing needle inner diameter and polymer solution concentration but decreased with increasing working distance for all four polymers. Neither NVES nor PVES altered the chemical structure of gelatin, PLGA, and PBT. PVES and NVES resulted in fibrous membranes bearing positive charges and negative charges, respectively. PLGA and PBT fibrous membranes retained around 30% and 50%, respectively, of the initial charge one week after electrospinning. Charges on gelatin and chitosan fibrous membranes were almost completely dissipated within 60 min of electrospinning. For all four polymers, under either PVES or NVES, the retained charges on fibrous membranes increased with increasing applied electrospinning voltage. This study explored a new approach for forming fibrous scaffolds by using NVES and has opened a new area for developing negatively charged fibrous scaffolds for tissue engineering applications.

Electrospinning is a process for generating micrometer or nanometer scale polymer fibers with large surface areas and high porosity. For tissue engineering research, the electrospinning technique provides a quick way to fabricate fibrous scaffolds with dimensions comparable to the extracellular matrix (ECM). A variety of materials can be used in the electrospinning process, including natural biomaterials as well as synthetic polymers. The natural biomaterials have advantages such as excellent biocompatibility and biodegradability, which can be more suitable for making biomimic scaffolds. In the last two decades, there have been growing numbers of studies of biomaterial fibrous scaffolds using the electrospinning process. In this review, we will discuss biomaterials in the electrospinning process and their applications in tissue engineering.