Fabrication and Degradation of Electrospun Scaffolds from L-Tyrosine-Based Polyurethane Blends for Tissue Engineering Applications

Abstract

It is important to control the degradation rate of a tissue-engineered scaffold so that the scaffold will degrade in an appropriate matching rate as the tissue cells grow in. A set of potential tissue engineering scaffolds with controllable rates of degradation were fabricated from blends of two biocompatible, biodegradable L-tyrosine-based polyurethanes (PEG 1000 -HDI-DTH and PCL 1250 -HDI-DTH) using the electrospinning process. The scaffolds were characterized by mat morphology, fiber diameter, diameter distribution, pore size, and hydrolytic degradation behavior. The majority of the scaffolds, despite having radically different chemical compositions, possessed no statistical difference with pore sizes and fiber diameters. The degradation pattern observed indicated that scaffolds consisting of a greater mass percentage of PEG 1000 -HDI-DTH decayed to a greater extent than those containing higher concentrations of PCL 1250 -HDI-DTH. The degradation rates of the electrospun scaffolds were much higher than those of the thin cast films with same compositions. These patterns were consistent through all blends. The work demonstrates one practical method of controlling the degradation of biopolymer scaffolds without significantly affecting an intended morphology.

Polyurethane-based scaffolds for myocardial tissue engineering

“…5 mg) was encapsulated in a hermetic aluminium pan before analysis. The sample was then heated from 208C to 2008C at 108C min 21 (first heating scan), isothermally maintained at 2008C for 3 min, cooled to 2608C at 108C min 21 (cooling scan), isothermally maintained at 2608C for 3 min and reheated from 2608C to 2008C at 108C min 21 (second heating scan) under nitrogen. All thermograms were analysed using the TA UNIVERSAL ANALYSIS software.…”

“…15 mg) in an alumina crucible and heated under air to a temperature range of 50-8008C at a heating rate of 108C min 21 (non-isothermal TGA). Isothermal TGA was also performed: the PU sample was heated from 508C to 1658C at 308C min 21 and isothermally maintained at 1658C for 60 min to simulate the thermal treatment of PU melt during scaffold fabrication in order to detect any thermal degradation phenomena. All the recorded data were analysed using the TA UNIVERSAL ANALYSIS software.…”

“…, frequency ¼ 0.5 rad s 21 and strain ¼ 0.5%) and frequency sweep tests (frequency range ¼ 0.1-100 rad s 21 and strain ¼ 0.5%, at 1658C). Time sweep tests were also performed, to study polymer stability during the tests (frequency ¼ 0.5 rad s 21 and strain ¼ 0.5%, at 1658C for 30 min).…”

“…Time sweep tests were also performed, to study polymer stability during the tests (frequency ¼ 0.5 rad s 21 and strain ¼ 0.5%, at 1658C for 30 min). A value of strain was selected in order to have a torque within the sensitivity of the instrument in the linear viscoelastic region.…”

Synthesis and structure-property relationships of biodegradable polyurethanes

“…New synthesis and fabrication strategies for BioPUs are often focused on tuning scaffold degradability without significantly affecting all morphological properties. Spagnuolo and Liu [175] prepared two similar L-tyrosine (DTH)-based PUs, blended them in the desired ratios, electrospun into morphologically acceptable fibrous scaffolds, characterized and subjected them to hydrolytic degradation testing. The scaffolds containing a higher percentage of the less resilient PEO 1000 -HDI-DTH degraded to a greater extent than those containing a lower percentage of the polymer (or a higher percentage of PCL 1250 -HDI-DTH) regardless of the composition of blends and configurations (electrospun scaffold and thin films).…”