X-ray Tomographic Imaging of Tensile Deformation Modes of Electrospun Biodegradable Polyester Fibers

Jekaterina Maksimcuka; Akiko Obata ; William W. Sampson ; Remi Blanc ; Chunxia Gao ; Philip J. Withers ; Olga Tsigkou ; Toshihiro Kasuga ; Peter D. Lee ; Gowsihan Poologasundarampillai - School of Materials, University of Manchester, Manchester (UK) ; Division of Advanced Ceramics, Nagoya Institute of Technology, Nagoya, Japan ; Thermo Fisher Scientific, Bordeaux, France ; Manchester X-ray Imaging Facility, University of Manchester, Manchester (UK) ; Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell (UK)

Electrospun constructs for the repair of load-bearing tissues are required to have adequate mechanical properties. However, the failure mechanisms of electrospun fibrous materials are not well understood. Existing literature focuses on failure modes of individual fibers and/or on bulk mechanical properties of whole fiber mats.

Electrospinning allows the production of fibrous networks for tissue engineering, drug delivery, and wound healing in health care. It enables the production of constructs with large surface area and a fibrous morphology that closely resembles the extracellular matrix of many tissues. A fibrous structure not only promotes cell attachment and tissue formation but could also lead to very interesting mechanical properties. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) is a biodegradable polyester that exhibits a large (>400%) elongation before failure. In this study, synchrotron X-ray phase contrast imaging was performed during tensile deformation to failure on a non-woven fiber mat of P(3HB-co-4HB) fibers. Significant reorientation of the fibers in the straining direction was observed, followed by localized necking and eventual failure. From an original average fiber diameter of 4.3 µm, a bimodal distribution of fiber diameter (modal diameters of 1.9 and 3.7 µm) formed after tensile deformation. Extensive localized necking (thinning) of fibers between (thicker) fiber–fiber contacts was found to be the cause for non-uniform thinning of the fibers, a phenomenon that is expected but has not been observed in 3D previously. The data presented here have implications not only in tissue regeneration but for fibrous materials in general.

How Amira-Avizo Software is used

Avizo (Thermo Fisher Scientific)  was used for data processing and visualization. Avizo, a commercially available software package, was used for all the visualization and image analysis performed in this study and described below. The process involves readily available modules from the software, and a few custom tools developed using its python scripting interface.