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

Jekaterina Maksimcuka,William W Sampson,Akiko Obata,Chunxia Gao,Philip J Withers,Gowsihan Poologasundarampillai,Toshihiro Kasuga,Peter D Lee,Remi Blanc,Olga Tsigkou

doi:10.3389/fmats.2017.00043

Abstract

Electrospinning allows the production of fibrous networks for tissue engineering, drug delivery and wound healing in healthcare. 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 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 fibre mat of P(3HB-co-4HB) fibres. Significant reorientation of the fibres in straining direction was observed, followed by localised necking and eventual failure. From an original average fibre diameter of 4.3 μm a bimodal distribution of fibre diameter (modal diameters of 1.9 and 3.7 μm) formed after tensile deformation. Extensive localised necking (thinning) of fibres between (thicker) fibre-fibre contacts was found to be the cause for non-uniform thinning of the fibres, a phenomenon that is expected, but has not been observed in 3D previously. The data presented here has implications not only in tissue regeneration but for fibrous materials in general.

Highlights

Electrospun constructs for the repair of load-bearing tissues are required to have adequate mechanical properties
We investigate the tensile deformation of a biodegradable polyester, P(3HB-co-4HB), that undergoes large elongation to failure using a bespoke tensile tester (P2R) and synchrotron X-ray tomography to shed light on structure–property relationships
Fiber mats with homogenous fiber morphology were obtained for P(3HB-co-4HB) solutions prepared with chloroform/acetone ratio of 100/0, 75/25, 65/35, and 50/50 (Figure 1B; Figure S2 in Supplementary Material)

Summary

Introduction

Electrospun constructs for the repair of load-bearing tissues are required to have adequate mechanical properties. Existing literature focuses on failure modes of individual fibers and/or on bulk mechanical properties of whole fiber mats In this manuscript, we investigate the tensile deformation of a biodegradable polyester, P(3HB-co-4HB), that undergoes large elongation to failure using a bespoke tensile tester (P2R) and synchrotron X-ray tomography to shed light on structure–property relationships. Biodegradable and biocompatible polymers are in use to produce implant materials for tissue regeneration. Polyesters such as poly(l-lactic acid) (PLLA) and poly(l-glycolic acid) (PLGA) are used in several FDA-approved medical devices (Jamshidian et al, 2010; Makadia and Siegel, 2011). P(3HB-co-4HB) has considerable potential for use as a biodegradable material in implants requiring large elongation

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Conclusion