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High mineralization activity is a crucial requirement in bone tissue engineering. In this study, a novel calcium citrate compounded amorphous calcium phosphate (CAP)/polyurethanes (PUs) composite porous 3D scaffold was developed by in situ polymerization via gas foaming method. The physical and chemical properties were characterized and discussed. The results showed that the HDI can react mildly with hydroxyl (–OH) groups of PEG, while gas foaming action was caused by the release of CO2 occurred in the reactive process, resulting in a uniform porous structure of PUs scaffold. The porosities of the synthetic PEGCAP porous scaffolds are all above 70% with high interconnectivity, while the porosity decreased 27% with increasing CAP to 40%. Furthermore, the mechanical properties of porous scaffolds enhanced about 16 times after addition of CAP. After immersing in simulated body fluid (SBF), the surface structure of the porous scaffold kept stable, and surface deposits formed, indicating that the porous scaffold has good mineralization activity. In addition, the in vitro cells proliferation assay confirms the excellent bioactivity of PEGCAP porous scaffolds. [ABSTRACT FROM AUTHOR]

In this study, porous composite materials were prepared from calcium citrate (CC) and polylactic acid (PLA). Scanning electron microscopy (SEM) showed that the prepared composite materials had the uniformly pore distribution and suitable pore size for bone tissue engineering and displayed proper mechanical properties. As confirmed in X-ray diffraction (XRD), SEM and thermal analysis, the lipophilic property of CC had the improved compatibility and uniform dispersion in the PLA matrix. In addition, the prepared materials showed the high mineralization activity and the ability to guide the formation of apatite since the hydrophilicity of CC improved the wettability of the composite materials. In vivo animal experiments showed that the material was nontoxic and had good biocompatibility. Furthermore, the synergic degradation of CC and PLA effectively neutralized the acidic environment, thus preventing partial inflammation caused by acidic products. CC/PLA composite materials provide a promising new bone repair material for bone tissue engineering. [ABSTRACT FROM AUTHOR]

In this study, a novel hydroxyapatite (HA)/polyurethane (PU) composite porous 3D scaffold was developed by in situ polymerization. Aliphatic hexamethylene diisocyanate (HDI) as a nontoxic and safe agent was adopted to produce the rigid segment in PU polymerization. HA powder was compounded in a PU polymer matrix during the polymeric process. The macrostructure and morphology as well as mechanical strength of the scaffolds were characterized by FTIR, XRD and SEM. The results show that the HDI can react mildly with hydroxyl (–OH) groups of polytetramethylene ether glycol and a mild foaming action caused by the release of CO2 gas occurred simultaneously in the reactive process, thus producing a uniform porous structure of HA/PU scaffold. The HA/PU composite scaffold with a high HA content of about 30 wt% has a porosity of more than 60% and a pore size from 100 to 800 μm. After immersed in simulated body fluid, the scaffolds were investigated by weight loss experiments and FTIR. The results show that polymerized component of HA/PU scaffolds degraded gradually in vitro, while HA component presented a classic trend of dissolution then deposition procedure. Three hydrolysis processes may happen in the PU degradation. The HA/PU scaffolds should be a promising material for bone tissue regeneration in clinic. [ABSTRACT FROM AUTHOR]

In this study, a novel polyurethane porous 3D scaffold based on polyethylene glycol (PEG) and polytetrahydrofuran glycol (PTMG) was developed by in situ polymerization and freeze drying. Aliphatic hexamethylene diisocyanate (HDI) as a nontoxic and safe agent was adopted to produce the rigid segment in polyurethane polymerization. The chemical structure, macrostructure, and morphology—as well as mechanical strength of the scaffolds—were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and tensile tests. The results show that the HDI can react mildly with hydroxyl (–OH) groups of PEG and PTMG, while gas foaming action caused by the release of CO2 occurred simultaneously in the reactive process, resulting in a uniform porous structure of PU scaffold. Moreover, the scaffolds were soaked in water and freeze dried to obtain higher porosity and more interconnective microstructures. The scaffolds have a porosity of over 70% and pore size from 100 to 800 μm. The mechanical properties increased with increasing PEG content, while the hydrophilicity increased as well. After immersion in simulated body fluid (SBF), the scaffolds presented a stable surface structure. The gas foaming/freezing drying process is an excellent method to prepare skin tissue engineering scaffold from PTMG/PEG materials with high porosity and good inter connectivity. [ABSTRACT FROM AUTHOR]