Tissue engineering scaffolds formed by pseudo-negative voltage electrospinning

Abstract

Microand nanofibrous materials are used in numerous applications, including chemical engineering, healthcare, and the military. Various techniques, including template synthesis, drawing, phase separation, and electrospinning, have been developed to produce ultrafine polymeric fibers. Among these, electrospinning has received considerable attention because of its ease of operation and versatility. Additionally, it is capable of fabricating fibers of different substances—such as polymers, proteins, and inorganic materials—with high surface area-tovolume ratios, as well as tunable fiber composition and morphology.1 Although the physical phenomenon of electrospinning was first observed in 1600, its usefulness was formally explored by Formhals in his patented work of 1934.2 Variations, such as coaxial,3 needle-less,4 and near-field electrospinning,5 have since been developed for a number of applications, including enzyme immobilization,6 environmental systems,7 sensors,8 and electronic and optical devices.9 In the biomedical field, electrospun fibrous materials are used for tissue engineering and drug delivery applications.10 In conventional electrospinning, high positive voltages (5–30kV) are used to form positively charged polymer jets and fibers. While positively charged biomaterials can be beneficial for tissue engineering,11 negatively charged scaffolds are also required because the surface charge of the biomaterials significantly affects cellular behavior.12 However, fiber formation with negative voltage electrospinning (NVES) is difficult for some polymers because the source solutions—before electrospinning—are positively charged. The attractive forces between such a solution and the negatively charged NVES needle inhibits polymer jet initiation from the needle tip. Here, we report our studies on fiber morphology, diameter, and surface charge of polymers fabricated using pseudo-negative voltage electrospinning (PNVES), which circumvents the direct application of negative voltage to the needle. Importantly, Figure 1. Schematic illustrating pseudo-negative voltage electrospinning (PNVES) with its applied electric (E-) field. V: Voltage.