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"Introduction. In the context of tissue engineering for regenerative medicine, the electrospinning technique consolidated itself as a valuable approach to fabricate tailored scaffolds. While its versatility lies in the possibility of controlling the process parameters, ambient parameters, and the properties related to the solvent system, the choice of the polymeric component itself results fundamental when designing a scaffold for a particular application. For tendon regeneration specifically, it is known the mechanical properties and alignment of the fibers play a major role in mimicking the features of native tendon, made of highly aligned and robust bundles of collagen fibrils. Poly(glycerol sebacate) (PGS) is a tough biodegradable polyester with elastomeric properties, easily synthesized through polycondensation of glycerol and sebacic acid; poly(ε-caprolactone) (PCL) is a semi-crystalline polyester widely employed in tissue engineering, with high miscibility potential with other polymers. Both polymers are biocompatible and bioresorbable, and their blend electrospinning can produce fibrous mats with promising mechanical properties. However, the optimization of the electrospinning process of this blend, especially in a benign solvent system1, and its application for tendon tissue engineering are mostly unexplored to this day2.
Methodology. PGS pre-polymer was synthesized and mildly crosslinked as reported elsewhere3. Mildly crosslinked PGS, PCL, and different ratios of PGS/PCL randomly oriented and aligned fibers were produced with a commercially available electrospinning setup in glacial acetic acid. The electrospinning parameters were an applied voltage of 15 kV, a tip-to-collector distance of 11 cm, and a flow rate ranging from 0.4 to 1.1 mL/h1. Randomly oriented and aligned fibers were collected on a drum rotating, respectively, at 500 and 1800 rpm. Morphological and chemical characterizations were carried out through Scanning Electron Microscopy and Fourier-Transformed Infrared Spectroscopy, degradation studies were conducted up to 14 days, and the mechanical properties were evaluated by standard uniaxial tensile testing.
Results. Homogeneous bead-free fibers were obtained. Characteristics absorption bands of PGS, PCL, and PGS/PCL fibers fabricated in presence of acetic acid were comparable to the ones found in literature. Pristine and blend fibers showed distinguishable degradation kinetics, attributable to the different degradation rates of PGS and PCL. Aligned fibers performed mechanically better than randomly oriented fibers, with PCL fibers having the highest ultimate tensile strength and strain at failure.
Conclusions. Aligned fibrous scaffolds from PGS, PCL and PGS/PCL were successfully produced through green electrospinning; the fibers were homogeneous and free of defects. Their mechanical properties met the requirements for tendon tissue engineering, with the ultimate tensile strength and Young’s modulus being comparable to the desirable values for the least demanding tendons, and the strain at failure being way higher than any native tendons, highlighting their potential use for tendon regeneration.
- Vogt, L. et al., Mater. Sci. Eng. C. 103 (2019)
- Fakhrali, A. et al., J Appl Polym Sci. e52136 (2022)
- Wang, Y. et al., Nat. Biotechnol. 20, 602 – 606 (2002)
Acknowledgments: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Maria Skłodowska-Curie Grant Agreement N° 955685"
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