Page 79 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

the development of sca olds with a lower sti ness in the physiological strain range.
In the present study, we set out to advance and refine the current LTE technology in order to explore the full range of possibilities this spinning method o ers with respect to gaining control of the void space and mechanical properties of electrospun sca olds. We therefore focused on elucidating the influence of ice crystal formation/fiber deposition rate as well as fiber sti ness, using the two biocompatible polymers PCL and PLA. These two materials exhibit a large di erence in Young’s modulus, allowing us to electrospin sca olds covering a large range of fiber sti ness. Additionally both materials are commonly employed in tissue engineering applications.33–36 Furthermore we have validated cell infiltration by seeding human vena saphena cells (HVSC) onto the most challenging sca old group (conventional spun versus LTE spun). The di erent electrospun sca olds were analyzed by mechanical testing and their 3 dimensional structure and void space was assessed and shown with computer tomography (CT) scans and scanning electron microscopy (SEM). Herewith, we aim to extend the range of the currently available sca old electrospinning toolbox, allowing control of void space and mechanical cues in sca olds to the values and ranges desired for the tissue one is aiming to replace.
4.3 Materials and Methods
4.3.1 Materials
Poly(lactic acid) (Grade H-100 Mitsui Chemicals, weight-average molecular weight Mw = 84’000 g/
mol, density ρ0 = 1.26 g/cm3, Young’s modulus E =
3.7 GPa, all datasheet values) was kindly provided
by Prof. J. W. Stark from ETH Zürich; and poly(ε- caprolactone) (CAPA 6800, Mw = 80’000 g/mol, ρ0 =
1.15 g/cm3, E = 440 GPa, all datasheet values) was
kindly supplied by White Chemicals (London, United
Kingdom). Pyridium formiate (PF) was formed by 4 mixing stoichiometric equivalents of pyridine (≥98
%; Sigma-Aldrich) and formic acid (≥96 %; Sigma- Aldrich).37
4.3.2 Electrospinning
The electrospinning was carried out on a set-up described previously23 at a voltage of 23 kV. The polymer solution flow speed was set at 2 ml/h and the distance between needle and the collector drum was maintained at 23 cm. Both polymers were electrospun from 10 % (w/w) chloroform (puriss, stabilized with ethanol; Sigma-Aldrich, St. Louis, USA) solutions. The solutions were prepared by dissolving the polymers under constant stirring overnight. To vary the electrospun fiber diameter, PF was added to the solutions at 1 % (w/w) and 10 % (w/w) relative to the total polymer content, respectively.
TAILORING THE VOID SPACE AND MECHANICAL PROPERTIES IN ELECTROSPUN SCAFFOLDS
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