Biodegradable polyurethanes: Comparative study of electrospun scaffolds and films

Abstract

The development of elastomeric bioresorbable and biocompatible segmented polyurethanes (SPU) for use in tissue engineering applications has been a subject of considerable interest in recent years. In this work, non-porous films and micro/nanofibrous scaffolds prepared from two different poly(ε-caprolactone)-based SPU previously synthesized using 1,6-hexamethylene diisocyanate and novel chain extenders containing urea groups or an aromatic aminoacid derivative, were studied. Thermal properties were influenced both by the different chemical structure of the hard segments and the processing conditions. Mechanical properties of the scaffolds showed elastic moludus, ultimate strain and tensile stress values adecuate for soft-tissue engineered constructs (i.e.: myocardial tissue). Film samples displayed low swelling degree (less than 2 wt %) in phosphate-buffered solution (PBS) at 37 ºC. The introduction of the aminoacid derivative chain extender with hydrolyzable ester bonds contributed to a higher degradation. Fibrous scaffolds exhibited higher hydrolytic stability than films at short times of assay, due to their more crystalline structures and higher degrees of association by hydrogen bonding, but also higher mass loss values in accelerated conditions (70 ºC), suggesting that degradation rate is not constant but depends on the degradation time and the processing technique.