Synthesis and characterization of novel elastomeric poly(D,L-lactide urethane) maleate composites for bone tissue engineering

Abstract

Here, we report the synthesis and characterization of a novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its composites with nano-hydroxyapatite (nHA) as potential weight-bearing composite. The 4PLAUMA/nHA ratios of the composites were 1:3, 2:5, 1:2 and 1:1. FTIR and NMR characterization showed urethane and maleate units integrated into the PLA matrix. Energy dispersion and Auger electron spectroscopy confirmed homogeneous distribution of nHA in the polymer matrix. Maximum moduli and strength of the composites of 4PLAUMA/nHA, respectively, are 1973.31 ± 298.53 MPa and 78.10 ± 3.82 MPa for compression, 3630.46 ± 528.32 MPa and 6.23 ± 1.44 MPa for tension, 1810.42 ± 86.10 MPa and 13.00 ± 0.72 for bending, and 282.46 ± 24.91 MPa and 5.20 ± 0.85 MPa for torsion. The maximum tensile strains of the polymer and composites are in the range of 5% to 93%, and their maximum torsional strains vary from 0.26 to 0.90. The composites exhibited very slow degradation rates in aqueous solution, from approximately 50% mass remaining for the pure polymer to 75% mass remaining for composites with high nHA contents, after a period of 8 weeks. Increase in ceramic content increased mechanical properties, but decreased maximum strain, degradation rate, and swelling of the composites. Human bone marrow stem cells and human endothelial cells adhered and proliferated on 4PLAUMA films and degradation products of the composites showed little-to-no toxicity. These results demonstrate that novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its nHA composites may have potential applications in regenerative medicine.

PLA-b-PEG/magnetite hyperthermic agent prepared by Ugi four component condensation

“…Figure 4 shows the 1 H-NMR spectra of the PLA homopolymers. It can be clearly seen from Figure 5 that only two peaks at 1.49 and 5.16 ppm appear, which are assigned to the methyl (CH 3 ) and methine (CH) signals from the PLA homopolymer, respectively [53]. These results are consistent with those obtained from PLA homopolymers prepared by the polycondensation of lactic acid [54].…”

Development and evaluation of elastomeric hollow fiber membranes as small diameter vascular graft substitutes

“…PLA was synthesized as described in our previous work [31]. For synthesis of the PLA degradable copolymer, 30 g of D,L-lactide were added to a 500 mL flask and slowly melted under stirring.…”

“…To simulate the rate of degradation of HFMs in the body, HFM samples (2 cm in length) were carefully weighed and placed in 2 mL of HBSS (0.40 g/L KCl, 0.06 g/L KH 2 PO 4 , 8.00 g/L NaCl, 0.0477 g/L Na 2 HPO 4 , and 0.35 g/L NaHCO 3 ) at 37°C for 8 weeks under sterile conditions, with time points every week, as performed in previous work [31]. HFM degradation was done in sealed containers to prevent both contamination and HBSS evaporation.…”

Vascularization in Bone Tissue Engineering Constructs

“…Elastomers have shown excellent properties for bone scaffold and vascular graft fabrication due to their biocompatibility, resorbability, and multiaxial load-bearing elastic properties. 80 For example, Yadong Wang and coworkers developed a heparin-coated porous polyglycerol sebacate (PGS) vascular graft with an outer polycaprolactone (PCL) shell for added mechanical strength. 117 More recently, we developed and characterized elastomeric hollow fiber membranes as small diameter vascular grafts, 81 with intended use in BTE constructs to initiate and establish vascular beds.…”