3D-microfibers improve the shear modulus of hydrogel composites
June 5-9, 2017
A major challenge in the field of biofabrication is to manufacture a construct soft enough to elicit optimal cell behavior while possessing the mechanical properties required to withstand the complex in-vivo mechanical environment . Hydrogels that were reinforced with polycaprolactone (PCL) fibers arranged in box structures, obtained by melt electrospinning writing (MEW), showed a synergistic increase in the compressive Young’s modulus , however, collapsed in-vivo, possibly due to shear stress. Here, we used MEW to produce specifically designed PCL fibers to stabilize an existing structure and subsequently improve the shear modulus of hydrogel-fiber composites. Instrument parameters affecting fabrication of these fibers were studied and stabilizing fibers used for shear testing (fiber diameter = 13.16 ± 0.11 μm) were made with an amplitude of 500 μm, wavelength of 400 μm, and collector velocity of 400 mm/min, at a height of 20 layers (330 m) (Figure 1A). The stabilizing fibers were embedded in 5, 10, and 15 wt.% polyacrylamide and a frequency sweep test (0.05 – 500 rad/s, 0.01% strain, n = 5) was performed to measure the complex shear modulus of the hydrogel-fiber composites. To correspond the direction of the stabilizing fibers with the torque of the rheometer, stabilizing fibers were printed in a specific architecture (Figure 1B). Stabilizing fibers increased the complex shear modulus by 148%, 127%, and 165%, when embedded within a 5%, 10%, and 15% polyacrylamide hydrogel, respectively (Figure 1C). This study highlights the capacity of MEW to increase shear properties of matrix-fiber composites through inclusion of stabilizing fibers.
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Mylène de Ruijter, Paul D. Dalton, Andrei Hrynevich, Jodie N. Haigh, Gernot Hochleitner, Jürgen Groll, Jos Malda, and Miguel D. Castilho, "3D-microfibers improve the shear modulus of hydrogel composites" in "Biofabrication for Hierarchical in Vitro Tissue Models", Jürgen Groll (University of Würzburg, Germany) Jos Malda (University Medical Centre Utrecht, The Netherlands) Eds, ECI Symposium Series, (2017). http://dc.engconfintl.org/biofab_tissue_model/11