Abstract
Biodegradable crosslinked polyurethane (cPU) was synthesized using polyethylene glycol (PEG), L-lactide (L-LA), and hexamethylene diisocyanate (HDI), with iron acetylacetonate (Fe(acac)3) as the catalyst and PEG as the extender. Chemical components of the obtained polymers were characterized by FTIR spectroscopy, 1H NMR spectra, and Gel Permeation Chromatography (GPC). The thermodynamic properties, mechanical behaviors, surface hydrophilicity, degradability, and cytotoxicity were tested via differential scanning calorimetry (DSC), tensile tests, contact angle measurements, and cell culture. The results show that the synthesized cPU possessed good flexibility with quite low glass transition temperature (T g, −22°C) and good wettability. Water uptake measured as high as 229.7 ± 18.7%. These properties make cPU a good candidate material for engineering soft tissues such as the hypopharynx. In vitro and in vivo tests showed that cPU has the ability to support the growth of human hypopharyngeal fibroblasts and angiogenesis was observed around cPU after it was implanted subcutaneously in SD rats.
Highlights
The rate of pharyngeal cancer has been increasing year after year due to alcohol and tobacco abuse [1]
The PLEG prepolymer was synthesized from the reaction of L-LA and polyethylene glycol (PEG)
The chemistry of PLEG was verified by Fourier transform infrared spectroscopy (FTIR) spectra (Figure 1), which showed characteristic spectra for PEG (b), L-LA (c), and PLEG 4 (d)
Summary
The rate of pharyngeal cancer has been increasing year after year due to alcohol and tobacco abuse [1]. Polyurethane is a widely used material in tissue engineering because of its good mechanical properties, biocompatibility, and biodegradability [9, 10]. It is usually synthesized via a crosslinking reaction between diisocyanate and polyhydric hydroxy with polyol or diamine as the extender. We studied the catalysis of aliphatic ester polymerization by low toxicity iron compounds, instead of the stannum compounds used commonly in research or/and industry [15] Using this approach, we synthesized a biocompatible and biodegradable copolymer with Tg of 5.6∘C from monomers of L-lactide, poly(ethylene glycol) (PEG), and NIPAAm [16]. We believe that the material presented in this paper will be a good substitute for hypopharyngeal tissue engineering
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