title: 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.
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Angel E
authors.initials: AE
authors.lastname: Mercado-Pagán
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Kang
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Dai Fei Elmer
authors.initials: DF
authors.lastname: Ker
authors.affiliation: Department of Prosthodontics, Dental Science Research Institute and BK21 Project, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Sangwon
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Yao
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Julius
authors.initials: J
authors.lastname: Bishop
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA ; Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
authors.forename: Yunzhi
authors.initials: Y
authors.lastname: Yang
keywords: Polyester urethanes; bone void fillers; ceramic composites; hydroxyapatite composites; load-bearing fillers; urethane composites