Fabrication of a mechanically anisotropic poly(glycerol sebacate) membrane for tissue engineering

Abstract

Poly(glycerol sebacate) (PGS) has been used successfully as a scaffolding material for soft tissue engineering. PGS scaffolds, however, are usually mechanically isotropic, which may restrict their use in tissue repairs as many soft tissues in the body have anisotropic mechanical behaviors. Although various methods have been used to fabricate anisotropic scaffolds, it remains challenging to make anisotropic scaffolds from thermoset PGS. Here a new, simple method to fabricate an anisotropic PGS membrane which can then be used to construct thicker three-dimensional anisotropic scaffolds was developed. First, an aligned sacrificial poly(vinyl alcohol) fibrous membrane was prepared by electrospinning. The fibrous membrane was then partially immersed in PGS prepolymer solution, resulting in a composite membrane upon drying. After curing, the sacrificial fibers within the membrane were removed by water, supposedly leaving aligned cylindrical pores in the membrane. Both SEM and AFM illustrated aligned grooves on the surface of the resultant PGS membrane, indicating the successful removal of sacrificial fibers. The PGS membrane was validated to be mechanically anisotropic using uniaxial tensile testing along and perpendicular to the predominant pore direction. The in vitro cytocompatibility of the PGS membrane was confirmed. As a demonstration of its potential application in vascular tissue engineering, a tubular scaffold was constructed by wrapping a stack of two axisymmetric pieces of the anisotropic PGS membranes on a mandrel. The compliance of the scaffold was found to depend on the pitch angle of its double helical structure, imitating the anisotropic mechanical behavior of the arterial media. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 760-770, 2018.

Use of Aligned Microscale Sacrificial Fibers in Creating Biomimetic, Anisotropic Poly(glycerol sebacate) Scaffolds

“…The preparation procedure of the anisotropic PGS membrane was similar to that published earlier [24], except that PLA/PEO instead of PVA was used to prepare the sacrificial fibers. First, PEO/PLA blend electrospun membranes were fabricated [27].…”

“…The morphology of the PLA electrospun membranes, PLA-PGS composite membranes, and PGS membranes was examined by SEM [24]. Briefly, dried samples were mounted, sputter-coated with platinum, and observed in a scanning electron microscope (S-4100, Hitachi, Japan).…”

“…Uniaxial tensile testing was performed using a custom-made mechanical tester, according to a published protocol [24]. Briefly, dog bone-shaped specimens were punched from the isotropic and anisotropic PGS membranes along and perpendicular to the predominant pore direction, if any, using a miniature ASTM D412-C die.…”

“…Recently, we have developed a relatively simple method to fabricate an anisotropic PGS membrane, with the use of aligned sacrificial poly(vinyl alcohol) (PVA) fibers [24]. Briefly, a composite membrane is first formed by embedding aligned PVA fibers in pPGS.…”

Polyglycerol Hyperbranched Polyesters: Synthesis, Properties and Pharmaceutical and Biomedical Applications

“…The microstructure of the electrospun fibers obtained from the blend of PCL and PGSeb in acetic acid is shown in Figure 7. Using PVA nanofibers as a template, Hsu et al reported the fabrication of an anisotropic PGSeb membrane: a sacrificial layer of aligned PVA fibers was immersed in the PGSeb prepolymer and, after curing, removed by water, leaving aligned cylindrical pores in the PGSeb membrane ( Figure 6h) [133]. The anisotropic PGSeb membranes exhibited a different Young's modulus and elongation at break along the pore direction versus perpendicular to the pore direction, but the ultimate tensile strength was the same in both directions.…”