Design and synthesis of biodegradable thermoplastic polyurethanes for tissue engineering

The aim of this study was to design and synthesise thermoplastic biodegradable and biocompatible polyurethanes for tissue engineering applications. A secondary aim was to tailor a range of degradation rates of the polyurethanes to suit a broad spectrum of tissue engineering applications. Various factors were systematically investigated in order to provide a means of controlling mechanical, thermal and degradation properties of the polyurethanes. The factors investigated included variation of the hard segment percentage, the diisocyanate, the soft segment macrodiol as well as the chain extender. Soft segment macrodiols were synthesised for this study including a poly(γ-butyrolactone) macrodiol which has been used to make biodegradable aliphatic poly(ester-urethane) for the first time. A novel range of degradable chain extenders was also developed and has been reported. The polymers were characterised using Gel Permeation Chromatography (GPC), Instron tensile testing, Differential Scanning Calorimetry (DSC) and Shore hardness. Cell culture testing was performed as was a three-month degradation study which showed the polyurethanes to be biocompatible and biodegradable respectively. Selected materials were shown to be suitable for scaffold fabrication using Fused Deposition Modelling (FDM), and the scaffolds made were further shown to support primary fibroblast growth in vitro.