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

Abstract

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.

Three-Dimensional Cotton-Wool-Like Polyhydroxybutyrate/Siloxane-Doped Vaterite Composite Fibrous Scaffolds: Effect of Imogolite-Coating on Physicochemical and Cell Adhesion Properties

“…MicroCT was used to image the 3D structures of Frontiers in Materials | www.frontiersin.org the electrospun materials (Figures 2-4). Synchrotron-based inline phase contrast µCT is a powerful method to image the 3D structures of electrospun polymeric materials under both static and dynamic conditions (Maksimcuka et al, 2017). Figures 2, 3 show the microCT images and quantification of the fiber morphologies of the fibremat and cotton-wool-like samples.…”

“…The prepared composite samples with a cottonwool-like structure are denoted by "PHA/SiV, " hereafter. For the tomographic imaging, PHA/SiV fibremat (non-woven) was fabricated using the same composite solution by electrospinning with a drum-shaped collector (Maksimcuka et al, 2017). The fibromat samples are denoted by "2D fibremat, " hereafter.…”

“…While, the elongations to failure of polymers PHB and P4HB are 5 or 1,000%, respectively. The ability to tune the physical property and in vivo durability of P(3HB-4HB) by varying the 4HB content in the copolymer makes it a useful material for development of scaffolds (Obata et al, 2013a;Nishizuka et al, 2014;Vigneswari et al, 2016;Maksimcuka et al, 2017;Zhijiang et al, 2017).…”

High‐resolution x‐ray tomographic morphological characterisation of electrospun nanofibrous bundles for tendon and ligament regeneration and replacement

“…This made the detection of the nanofibres direction even more difficult. To obtain tomographic scans with a resolution of 0.33 μm, synchrotron X‐ray phase contrast was used (Maksimcuka et al ., ): although this allowed identifying the individual polyester nanofibres (diameter between 1.9 and 3.7 μm), it also caused significant material modification due to the high radiation dose. Some works used contrast agents to enhance radiopacity during CT scans of portions of anterior cruciate ligaments and patellar tendons where the effects of phosphotungstig acid (PTA) and iodine solution (IKI) staining were compared, in order to increase the visualisation of the tissues, down to the fascicle level (Shearer et al ., ; Shearer et al ., ).…”

“…However the fibres’ contours were not clearly distinguishable, due to a significant partial volume effect. Very recently, tomographic scans with a resolution of 0.33 μm were produced using synchrotron x‐ray phase contrast imaging of mats of biodegradable polyester nanofibres with diameters between 1.9 and 3.7 μm (Maksimcuka et al ., ).…”