Electrospinning techniques can create a variety of nanofibrous scaffolds for tissue engineering or other applications. We describe here a procedure to optimize the parameters of the electrospinning solution and apparatus to obtain fibers with the desired morphology and alignment. Common problems and troubleshooting techniques are also presented.
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.
Note: The majority of the examples presented here deal with electrospinning poly-L-lactic acid (PLLA) nanofibers. This is simply because PLLA is the most commonly spun polymer in our laboratory. However, we have also successfully used these methods to electrospin other polymers (e.g., PLGA, PCL, PS) and believe that the techniques presented here are easily applicable to the majority of mid- to high-molecular weight polymer solutions.
The authors have nothing to disclose.
This work was supported by NIH K08 EB003996 and the Paralyzed Veterans of America Research Foundation Grant 2573.
Material Name | Tipo | Company | Catalogue Number | Comment |
---|---|---|---|---|
High voltage DC power supply | Gamma High Voltage | ES40P-5W | ||
Syringe pump | KD Scientific | KDS100 | ||
Aluminum foil | Reynolds | |||
Blunt metal tips, 23ga | Fisher | 13-850-102 | ||
Polypropylene syringe | BD | 309585 | ||
Rotating or stationary collector | Custom built | |||
Various alligator clips and wires | ||||
Dimethylformamide | Fisher | AC11622-0010 | ||
Chloroform | Fisher | AC42355-0040 | ||
PLLA | Boehringer Ingelheim | Resomer L210 | ||
PLGA 85:15 | Sigma | 43471 | ||
Carbon tape | Ted Pella | 13073-1 |