also been research into their reinforcement of hydrogels and matrices for superior mechanical properties [19–21]. In addition to their
use as scaffolds, MEW fibers have been used as fugitive inks for
imparting porosity into hydrogels [22].
One limitation of MEW is the small number of suitable polymers currently tested. To be processed via MEW, candidate polymers must melt at a practical temp (e.g., <200
C) and have good
melt flow properties under the influence of the electrical field
(electrorheological properties). To date the only polymers used
with MEW are poly(ε-caprolactone) (PCL) [23, 24], poly(hydroxymethylglycolide-co-ε-caprolactone) [13], poly(propylene) [25],
poly(L-lactide-co-ε-caprolactone-co-acryloyl carbonate) [26], selfassembling small molecules [27], and poly(2-ethyl-2-oxazoline)
[28]. When establishing MEW or working with new polymers, it
is important to reduce fiber pulsing—guidelines on identifying a
“printability” number and removing fiber pulsing have been published [7, 29]. For tissue engineering applications, using MEW of
PCL is particularly attractive as it has a low melting point (60
C)
and good electrorheological properties, has a history of use as
implantable medical devices, and is available in medical-grade
quality.
In this chapter we describe how to prepare scaffolds from PCL
using the MEW process and how these can be seeded with fibroblasts. Because MEW is still an evolving technique, this methods
chapter should act as a starting point with the reader encouraged to
try their own MEW scaffold designs and different cell types,
depending on the type of tissue being mimicked.
2 Materials
2.1 Melt
Electrospinning
Writing
1. Melt electrospinning machine—we have used an in-house-built
machine consisting of high voltage supply (up to +10 kV; low
micro-amperage unit), coil electrical heater, computer numerical control (CNC) x-y stage controlled with Mach3 CNC
controller software, and safety interlocks.
2. Spinneret: 23 gauge, 1
00 long Nordson
® EFD
® 5123 stainless
steel precision needle.
ä
Fig. 2 (continued) after 4 days (c) and 10 days (d) of culture. Reproduced under the terms and conditions of
the Creative Commons Attribution CC BY 3.0 License [16]. Copyright 2015, The Authors, published by IOP
Publishing. The samples were stained with TRITC-conjugated phalloidin (red) to visualize actin filaments and
Hoechst 33342 (blue) to visualize cell nuclei. Images e and f show primary human osteoblasts [12] after
14 days (e) and 4 weeks (f) of culture. Reproduced under the terms and conditions of the Creative Commons
CC BY License [12]. Copyright 2012, The Authors, published by AIP Publishing. The samples were stained with
TRITC-conjugated phalloidin (red) to visualize actin filaments and DAPI (blue) to visualize cell nuclei. e shows
an overlay of the fluorescent and transmission light microscopy image
114
Eleonore C. L. Bolle et al.
use as scaffolds, MEW fibers have been used as fugitive inks for
imparting porosity into hydrogels [22].
One limitation of MEW is the small number of suitable polymers currently tested. To be processed via MEW, candidate polymers must melt at a practical temp (e.g., <200
C) and have good
melt flow properties under the influence of the electrical field
(electrorheological properties). To date the only polymers used
with MEW are poly(ε-caprolactone) (PCL) [23, 24], poly(hydroxymethylglycolide-co-ε-caprolactone) [13], poly(propylene) [25],
poly(L-lactide-co-ε-caprolactone-co-acryloyl carbonate) [26], selfassembling small molecules [27], and poly(2-ethyl-2-oxazoline)
[28]. When establishing MEW or working with new polymers, it
is important to reduce fiber pulsing—guidelines on identifying a
“printability” number and removing fiber pulsing have been published [7, 29]. For tissue engineering applications, using MEW of
PCL is particularly attractive as it has a low melting point (60
C)
and good electrorheological properties, has a history of use as
implantable medical devices, and is available in medical-grade
quality.
In this chapter we describe how to prepare scaffolds from PCL
using the MEW process and how these can be seeded with fibroblasts. Because MEW is still an evolving technique, this methods
chapter should act as a starting point with the reader encouraged to
try their own MEW scaffold designs and different cell types,
depending on the type of tissue being mimicked.
2 Materials
2.1 Melt
Electrospinning
Writing
1. Melt electrospinning machine—we have used an in-house-built
machine consisting of high voltage supply (up to +10 kV; low
micro-amperage unit), coil electrical heater, computer numerical control (CNC) x-y stage controlled with Mach3 CNC
controller software, and safety interlocks.
2. Spinneret: 23 gauge, 1
00 long Nordson
® EFD
® 5123 stainless
steel precision needle.
ä
Fig. 2 (continued) after 4 days (c) and 10 days (d) of culture. Reproduced under the terms and conditions of
the Creative Commons Attribution CC BY 3.0 License [16]. Copyright 2015, The Authors, published by IOP
Publishing. The samples were stained with TRITC-conjugated phalloidin (red) to visualize actin filaments and
Hoechst 33342 (blue) to visualize cell nuclei. Images e and f show primary human osteoblasts [12] after
14 days (e) and 4 weeks (f) of culture. Reproduced under the terms and conditions of the Creative Commons
CC BY License [12]. Copyright 2012, The Authors, published by AIP Publishing. The samples were stained with
TRITC-conjugated phalloidin (red) to visualize actin filaments and DAPI (blue) to visualize cell nuclei. e shows
an overlay of the fluorescent and transmission light microscopy image
114
Eleonore C. L. Bolle et al.