The Mechanical Properties of Electrospun Collagen/PCL Single Fibers and Fibrous Scaffolds

Abstract

Collagen/Poly-ε-caprolactone (PCL) blended fibers were electrospun from a solution of 2.5% wt./vol. bovine collagen, 2.5% wt./vol. PCL and 95% 1,1,1,3,3,3-hexaflouro-2-propanol (HFP). A combined atomic force microscopic (AFM)/optical microscopic technique was used to study the properties of individual fibers in buffer. Mechanical testing of fibers was done using the AFM to laterally stretch individual fibers suspended over 13.5μm wide groves in a transparent substrate. The optical microscope, located below the sample, was used to monitor the stretching process. Fibrous scaffolds of these blends were also electrospun to test the bulk mechanical properties. A total of 5ml of 5% wt./vol. solution of blended collagen/PCL was used to electrospin scaffolds with a 4.75mm inner diameter to be used to for blood vessel tissue replacements. Dots are applied to the surface of the scaffold which is then subjected to cyclic loading under wet conditions while video is being recorded of the test. When a replicable elastic mechanical behavior is achieved, the strain found in the loading part of the cycle is analyzed using non-contact video strain measurements. By testing the single fiber mechanical properties of these blends as well as the bulk mechanical properties of a fibrous scaffold we are able to determine the mechanical differences of the fibers on both a micro and macro scaffold. These results can be used to better develop tissue engineered scaffolds for blood vessel replacements.