Electrospinning Fundamentals: Optimizing Solution and Apparatus Parameters

Abstract

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form -although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques. Video LinkThe video component of this article can be found at

Fabricating Superhydrophobic Polymeric Materials for Biomedical Applications

“…If the difficulties remain, it may be necessary to switch to a different electrospinning solvent. For more troubleshooting, Leach and coworkers 47 provide a comprehensive troubleshooting guide to electrospinning.…”

“…In addition to these adjustments, it may be necessary to adjust the tip-to-collector distance if the fibers/particles appear wet or if adjusting the voltage does not adequately solve a dragging droplet at the needle tip. Note: For detailed troubleshooting, see the comprehensive electrospinning optimization process by Leach and co-workers 47 . Electrospraying will generally involve higher voltages and lower solution concentrations than electrospinning.…”

Nanomaterials for neural tissue engineering

“…voltage, distance from target, needle © Woodhead Publishing Limited, 2013 identity, and temperature) can be altered to fabricate various types of fi bers for different applications. The mechanical properties of the NFs (e.g., thickness, composition, surface area, and porosity) are adjusted by controlling the solution and process parameters to optimize the alignment, stability, and morphology (Cunha et al ., 2011 ;Leach et al ., 2011b ). For different applications, the collection schemes can be varied as single ground, rotating single ground, horizontal ring, and in vitro onto cells (Ishaug-Riley et al ., 1999 ).…”

Tissue engineered micro and macrovasculature utilizing stromal vascular fraction.

“…The liquefied polymer, as it moves through the air in a whipping fashion, evaporates the solvent and fibers are left for deposition onto a collection surface producing a randomly-oriented fibrous mat or tube. Fiber morphology can be changed by altering electrospinning parameters such as solution viscosity, electrical conductivity, polymer molecular weight, flow rate of solution, spinning distance, applied voltage, and humidity and temperature 224 . Altering parameters allows high variation in electrospun products for the production of micro-scale textures and pores resembling endogenous ECM, allowing cellular infiltration either in vivo or in vitro 225 .…”