Vhx 500fe

Mechanical properties of nonimplanted control scaffolds (bilayered [n = 6]; unilayered microporous [n = 6]; unilayered nanoporous [n = 4]) and explants were analyzed in wet conditions at 37°C in a biaxial tensile setup (CellScale Biomaterial Testing, Waterloo, Canada) in combination with LabJoy software (V8.01; CellScale Biomaterial Testing). Specimens were longitudinally opened, followed by thickness measurements using a digital microscope (Keyence VHX-500FE, Itasca, IL). Subsequently, the specimen's axial and circumferential directions were aligned with the actuators and mounted. Before testing, specimens were sprayed with graphite to facilitate optical strain analysis. After a precondition protocol of 10 cycles of uniaxial strain up to 10% in each direction, the samples were equibiaxially stretched at a strain rate of 100% min -1 until failure. Assuming incompressibility and plane-stress conditions, Cauchy stress-stretch curves were calculated from the force and displacement measurements. As a measure of stiffness, the slope of the stress-strain curve (Elastic modulus) was calculated. 19

To produce 3D microporous scaffolds, CE-UPy-PCL, either with or without increasing concentrations of UPy-HBP (i.e. 0.5 mol%, 1 mol%, 2 mol%), was dissolved in chloroform (CHCl 3 ; Sigma) and Hexafluoro-2-propanol (HFIP; Sigma) (15% w/v polymer in CHCl 3 / HFIP 80/20% v/v). After being stirred overnight at room temperature, the polymer solution was used to fabricate electrospun meshes on an IME technologies EC-CLI equipment (IME Technologies, Geldrop, The Netherlands). The polymer solution was dispensed via a syringe pump (PHD 22/2000, Harvard Apparatus, Holliston, MA) to a moving 14 G needle placed at 17 cm distance from a rotating cylindrical mandrel wrapped with aluminum foil (diameter, 25 mm; rotation speed, 100 rpm). The solution flowed at 35 lL/min in presence of 18 kV voltage, at constant temperature of 23 °C and 30% relative humidity. The voltage of the collector was set to 0 kV for CE-UPy-PCL and À1 kV for CE-UPy-PCL+UPy-HBP. The resulting fibre diameter was measured with scanning electron microscopy (SEM, Quanta 600F, FEI, Eindhoven, The Netherlands), and averaged over 10 fibres per image (250X magnification), with 5 images in total per scaffold. The overall thickness of the electrospun sheet was measured at 10 different locations with a highpower digital microscope (VHX-500FE, Keyence, Mechelen, Belgium). Results are presented as mean ± standard deviation.