The surgery of tendons and ligaments ruptures, especially in old patients, requires permanent prosthetic devices with a biomimetic hierarchical structure and mechanical properties [1]. The electrospinning technique has demonstrated to produce complex hierarchical structures mimicking the morphology and properties of tendons and ligaments [2, 3]. The aims of the present study were: (i) to develop innovative hierarchically arranged electrospun structures made of inert Nylon 6,6 for tendon and ligament replacement; (ii) to investigate their structure with high-resolution x-ray computed tomography (XCT); (iii) to characterize their mechanical properties. In order to mimic the arrangement of tendons and ligaments fibrils [4], mats of aligned Nylon 6,6 nanofibers were electrospun on a rotating drum collector [5]. To reproduce the tendons and ligaments fascicles morphology [4], mats were cut in stripes and wrapped up on the drum, producing ring-shaped bundles of axially aligned nanofibers [2]. In order to mimic a whole tendon or ligament with their epitenon-epiligament membranes [4], 2-level hierarchical structures were developed. Several bundles were aligned and packed together using a nanofibrous sheath produced through an innovative electrospinning setup [2]. Finally, to mimic also the endotenon-endoligament membranes [4], a 3-level hierarchical structure was obtained by grouping together three 2-level hierarchical structures, produced as previously described, with an additional electrospun sheath. A morphological investigation of the different electrospun structures was carried out with scanning electron microscopy (SEM) and XCT with different voxel sizes (0.4 up to 5 m). The alignment of the nanofibers of the electrospun sheaths and of the internal bundles was quantified with a previously validated methodology [6]. The ring-shaped bundles and the 2-level hierarchical structures were also mechanically characterized with a monotonic tensile test with physiological strain rates (70%/sec.). The high-resolution imaging confirmed that the morphology of the different hierarchical structures was comparable to the corresponding structures of biological tendons and ligaments [4]. The mechanical test on the structures showed a biofidelic biomimicking of the mechanical performances of the corresponding tendons and ligaments structures. In conclusion, this innovative electrospinning approach to produce hierarchically-arranged structures will be suitable to develop tendons and ligaments prosthetic devices.
A. Sensini, C.G. (2019). High-resolution x-ray morphological investigation of Nylon 6,6 electrospun assemblies reproducing the hierarchical structure and mechanical performances of tendons and ligaments.
High-resolution x-ray morphological investigation of Nylon 6,6 electrospun assemblies reproducing the hierarchical structure and mechanical performances of tendons and ligaments
SENSINI, ALBERTO;ZUCCHELLI, ANDREA;M. L. Focarete;C. Gualandi;L. Cristofolini
2019
Abstract
The surgery of tendons and ligaments ruptures, especially in old patients, requires permanent prosthetic devices with a biomimetic hierarchical structure and mechanical properties [1]. The electrospinning technique has demonstrated to produce complex hierarchical structures mimicking the morphology and properties of tendons and ligaments [2, 3]. The aims of the present study were: (i) to develop innovative hierarchically arranged electrospun structures made of inert Nylon 6,6 for tendon and ligament replacement; (ii) to investigate their structure with high-resolution x-ray computed tomography (XCT); (iii) to characterize their mechanical properties. In order to mimic the arrangement of tendons and ligaments fibrils [4], mats of aligned Nylon 6,6 nanofibers were electrospun on a rotating drum collector [5]. To reproduce the tendons and ligaments fascicles morphology [4], mats were cut in stripes and wrapped up on the drum, producing ring-shaped bundles of axially aligned nanofibers [2]. In order to mimic a whole tendon or ligament with their epitenon-epiligament membranes [4], 2-level hierarchical structures were developed. Several bundles were aligned and packed together using a nanofibrous sheath produced through an innovative electrospinning setup [2]. Finally, to mimic also the endotenon-endoligament membranes [4], a 3-level hierarchical structure was obtained by grouping together three 2-level hierarchical structures, produced as previously described, with an additional electrospun sheath. A morphological investigation of the different electrospun structures was carried out with scanning electron microscopy (SEM) and XCT with different voxel sizes (0.4 up to 5 m). The alignment of the nanofibers of the electrospun sheaths and of the internal bundles was quantified with a previously validated methodology [6]. The ring-shaped bundles and the 2-level hierarchical structures were also mechanically characterized with a monotonic tensile test with physiological strain rates (70%/sec.). The high-resolution imaging confirmed that the morphology of the different hierarchical structures was comparable to the corresponding structures of biological tendons and ligaments [4]. The mechanical test on the structures showed a biofidelic biomimicking of the mechanical performances of the corresponding tendons and ligaments structures. In conclusion, this innovative electrospinning approach to produce hierarchically-arranged structures will be suitable to develop tendons and ligaments prosthetic devices.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.