Improving the degradation behavior and in vitro biological property of nano-hydroxyapatite surface- grafted with the assist of citric acid

Functionalized Titanium Nanoparticles Induce Oxidative Stress and Cell Death in Human Skin Cells

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A combined-modification method of carboxymethyl β-cyclodextrin and lignin for nano-hydroxyapatite to reinforce poly(lactide-co-glycolide) for bone materials

Lignin is the second most abundant natural biomacromolecule. A new surface-modification for nano-hydroxyapatite (n-HA) by carboxymethyl β-cyclodextrin (CM-β-CD) and lignin and its reinforce effect for poly(lactide-co-glycolide) (PLGA) were investigated by Fourier transformation infrared (FTIR), X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), dispersion images, the tensile tests, scanning electron microscope (SEM), differential scanning calorimeter (DSC) and polarized optical microscopy (POM), compared to the singled-modification of CM-β-CD or lignin. The results showed that the appropriate combined-modified n-HA displayed excellent synergistic effects for increasing the dispersion, yielding good interfacial bonding between n-HA with PLGA matrix. The tensile strength of the composite was still 14.53% higher than that of PLGA, for a n-HA addition amount of 15 wt%, which was significantly better than that for the singled-modified n-HA. Additionally, in vitro degradation behavior was evaluated by soaking in simulated body fluid (SBF), and their cell response was carried out by interaction tests with bone mesenchymal stem cells. The results indicated that the combined-modification method promoted good degradation behavior and apatite deposition, as well as excellent cell biocompatibility. This study may offer an important guidance to obtain PLGA-based composites reinforced by surface-modified n-HA as bone materials.

Repair of the calvarial defect in goat model using magnesium-doped porous hydroxyapatite combined with recombinant human bone morphogenetic protein-2

Hydroxyapatite (HA) is a representative bone repairing biomaterial for its similar composition to human bones and teeth. However, pure HA is limited in application for some unwanted characteristic, such as it is brickle and weakness in degradation. In this study, we modified HA by doping magnesium (Mg) to the material and studied its property in vitro. Besides, we also evaluated the calvarial defect repair effect using MgHA combined with rhBMP-2 in goat model. According to our outcomes, HA composited Mg made the scaffold smooth and the pore regular. In vitro study, Mg could increase the Ca releasing, which may reflect a faster degradation property modified by Mg. And then, MgHA improved the cell viability and proliferation. Furthermore, MgHA could increase the expression of ALP, Collagen I and VEGF protein compared with pure HA (p<0.5, respectively). In the vivo study, MgHA showed a better bone defect healing effect in computed tomography (CT) evaluation compared with HA (p<0.05), but it was inferior to the MgHA/rhBMP-2 (p<0.05). Besides, in the histological analysis, MgHA/rhBMP-2 showed the most effective bone formation outcome (p<0.05), and the MgHA group was significant better than the pure HA group on osteogenesis (p<0.05). Furthermore, Collagen I and VEGF mRNA expression at 12 week in MgHA/rhBMP-2 group were also significat higher than other two groups. In conclusion, Mg had effects on bone formation and angiogenesis, and MgHA/rhBMP-2 had improved the bone defect repair effect. It is worthy of being recommended to bone tissue engineering.