Page 83 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

TAILORING THE VOID SPACE AND MECHANICAL PROPERTIES IN ELECTROSPUN SCAFFOLDS
Figure 4.1 Influence of target area and electrospinning time on sca old porosity. Data for low-temperature electrospun (LTE) sca olds 4 produced with PCL (LTE PCL:30 mm,50 mm and100mm drum) and PLA (LTE PLA: 30 mm, 50 mm and 100 mm drum) and for
comparison, conventionally (conv.) spun PCL ☐ and PLA △ (both on a 50 mm drum) are shown. All sca olds are comprised of fibers of 9 μm
diameter.
We found that varying the ratio between the rate of fiber deposition and ice layer formation by changing the drum geometry did not result in a considerable change in the final overall porosity of both PLA and PCL LTE-spun sca olds (Figure 4.1). Porosities of ~98 % to 99.5 % were obtained for both polymers. These porosity values are substantially higher than the values obtained with conventional electrospinning methods (88 % to 92 %). This ~10% increase in porosity gained by LTE, which is notably an up to 10 fold decrease in sca old density, is also illustrated by the computer tomography scans presented in Figure 4.2.
The remarkable di erences in void spaces between sca olds spun using di erent
methodologies are summarized as follows: layered and dense structures are found for conventional electrospun sca olds (panels A and B in Figure 4.2), whereas increased inter-fiber distances are realized for the LTE sca olds (panels C and D in Figure 4.2). In fact, for the LTE sca olds, ultra-porous structures can be produced that feature a truly three-dimensional character with significantly increased void spaces and higher overall porosities.
Figure 4.1 suggests that for both polymers, i.e. PLA and PCL, longer spinning times resulted in a decrease in sca old porosity. This e ect was less pronounced when using the PLA, where overall higher sca old porosities were obtained compared
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