Tailoring the degradation kinetics of poly(ester carbonate urethane)urea thermoplastic elastomers for tissue engineering scaffolds

Abstract

Biodegradable elastomeric scaffolds are of increasing interest for applications in soft tissue repair and regeneration, particularly in mechanically active settings. The rate at which such a scaffold should degrade for optimal outcomes, however, is not generally known and the ability to select from similar scaffolds that vary in degradation behavior to allow such optimization is limited. Our objective was to synthesize a family of biodegradable polyurethane elastomers where partial substitution of polyester segments with polycarbonate segments in the polymer backbone would lead to slower degradation behavior. Specifically, we synthesized poly(ester carbonate)urethane ureas (PECUUs) using a blended soft segment of poly(caprolactone) (PCL) and poly(1,6-hexamethylene carbonate) (PHC), a 1,4-diisocyanatobutane hard segment and chain extension with putrescine. Soft segment PCL/PHC molar ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 were investigated. Polymer tensile strengths varied from 14-34 MPa with breaking strains of 660-875%, initial moduli of 8-24 MPa and 100% recovery after 10% strain. Increased PHC content was associated with softer, more distensible films. Scaffolds produced by salt leaching supported smooth muscle cell adhesion and growth in vitro. PECUU in aqueous buffer in vitro and subcutaneous implants in rats of PECUU scaffolds showed degradation slower than comparable poly(ester urethane)urea and faster than poly(carbonate urethane)urea. These slower degrading thermoplastic polyurethanes provide opportunities to investigate the role of relative degradation rates for mechanically supportive scaffolds in a variety of soft tissue repair and reconstructive procedures.

Assessment of aliphatic poly(ester-carbonate-urea-urethane)s potential as materials for biomedical application

“…DSC studies indicate that introduction of an ester component to the structure of poly(carbonate-urea-urethane)s resulted in decrease of T g with simultaneously a small amount of crystalline phase observed [41]. Similar changes of T g , in the range of −46 to −54°C, were described when oligo(ε-caprolactone) diol was mixed with oligo(hexamethylene carbonate) diol and used in poly(ester-carbonate-urethane-urea)s as a soft segments [42].…”

“…Samples based on oligo(δ-valerolactone-co-ε-caprolactone) diol, BDI and putrescine exhibited similar tensile strength, but much higher elongation at break, around 1300% [44]. In comparison to poly(ester-carbonate-urea-urethane)s described by Hong et al [42], which were synthesized from oligo(ε-caprolactone) and oligo(1,6-hexamethylene carbonate) diols, tetramethylene diisocyanate, and putrescine, our samples exhibited higher values of tensile strengths and simultaneously were characterized by lower elongation at break.…”

Synthesis and Thermal Properties of Poly(ethylene glycol)-polydimetylsiloxane Crosslinked Copolymers

“…PU can be synthesized by the reaction of polyol, isocyanate and occasionally chain extender is added to modify the properties of the polymer. Segmented PU has been widely studied over the past years because it gives merging of biocompatibility, elastomeric properties and thermoplastic processing conditions (Hong et al 2010;Wang et al 2009;Wu et al 2000). Therefore, it has various applications in industries and daily uses.…”

Hydrophylic Polyurethaneurea Containing the Copolymer of N-vinylpyrrolidone, Vinyl Acetate and Vinyl Alcohol for Possible Biomedical Use

“…The polyurethaneurea (PUU) are used in a variety of medical applications, such as the wound dressing [1], contact lenses [2], catheters, prostheses, blood vessels [3], antithrombogenous products [4], mechanically supporting constructions during the soft tissue reconstruction [5], metal stents coating of atherosclerotic blood vessels [6], surgical meshes [7,8] and bone tissue engineered [9,10], vascular tissue engineering [11].…”