Hard‐block degradable thermoplastic urethane‐elastomers for electrospun vascular prostheses

Abstract

Thermoplastic polyurethane (TPU) elastomers with biodegradable chain extenders were synthesized and tested for mechanical performance and biocompatibility. The design of the TPUs was based on structural modification of a mechanically appropriate aromatic isocyanate‐based TPU. As the aromatic isocyanate was substituted with a less toxic but also less “hard” aliphatic isocyanate, the chain extender plays an important role on the mechanical properties. Here, the terephthalate ester chain extender was found to work better than hydroxyl ethyl lactate in providing polymers with mechanical properties similar to commercial aromatic isocyanate‐based TPUs. The polymers were degraded in aqueous solutions at elevated temperatures and compared to polylactic acid (PLA) to partially simulate biodegradation. The lactate‐based TPUs degraded about twice as fast as PLA while the terephthalate‐based TPU degraded much more slowly. The latter material was processed by electrospinning to give a tubular graft approximately the size of a large rat blood vessel. Initial results from implantation of these TPUs into rats are promising and indicate that biodegradation occurs and is likely beneficial to cell proliferation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Biocompatible, degradable thermoplastic polyurethane based on polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone copolymers for soft tissue engineering

“…In CTC-PU(BET), the change of chain extender was indicated by the peaks’ shift to 4.32 and 8.13 ppm, which was ascribed to the CH–O bond adjacent to the ester bonds and the CH from the benzene ring, respectively. 19 These results suggested the successful synthesis of the three kinds of TPU elastomers.…”

“…18 These TPUs are recognized as biodegradable because they are normally synthesized using either polyester diols as soft segments or degradable chain extenders. 11, 19-21 The degradation rate can be tuned by varying the components and compositions of the reactants. PCL has been the most commonly used soft segment in biodegradable TPU synthesis although its degradation rate is relatively low.…”

Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

“…Dabagh and coworkers did not observe fibroblast proliferation differences between Estane and PDMS-modified Estane surfaces after culture for 48 hours [51]. Wagner [52, 53] and Liska [54, 55] developed degradable electrospun PEU vascular grafts comparable to commercially-available materials, showing good biocompatibility with cells in vitro and good mechanical properties, although complex PEU chemistry and fabrication were required to ensure this compatibility.…”

Fabrication and Characterization of Electrospun Thermoplastic Polyurethane/Fibroin Small-Diameter Vascular Grafts for Vascular Tissue Engineering

“…By altering the ratio of the soft and hard segments, TPU can be modified to reach the required elasticity and strength for vascular tissue engineering (Mi et al, 2015a; Jing et al, 2015). Conventional TPU is nonbiodegradable but a biodegradable TPU can be synthesized with its electrospun samples achieving satisfying biomechanical behaviors as vascular substitutes (Baudis et al, 2012; Bergmeister et al, 2015). Also, the in vivo trials of biodegradable TPU grafts show promising results with long-term patency and remodeling (Bergmeister et al, 2015).…”