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Composite biomaterials with hierarchical structures have emerged as new approaches for bone-tissue engineering. In this study, a biomimetic, osteoconductive tricomposite scaffold made of N-doped graphene–hydroxyapatite (NG–HA) hybrids blended with an agarose (AG) matrix was prepared via a facile hydrothermal/cross-linking/freeze-drying method. The structure and composition of AG/NG–HA were examined by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared, Raman spectroscopy, and thermogravimetric analysis. The as-prepared scaffolds showed hierarchical pore architecture and an organic–inorganic composition, which simulated the composition and structure of natural bone tissue. The effect of AG/NG–HA on bone mesenchymal stem cells (MSCs) osteoblast proliferation, differentiation, and mineralization was tested in vitro. The expression of osteogenic-related genes was determined by real-time polymerase chain reaction. Our results showed that the introduction of N-graphene into the hybrid scaffold significantly improved its mechanical properties, an effect that promoted the proliferation and viability of MSCs. Moreover, the scaffolds triggered selective differentiation of MSCs to osteogenic lineage while conferring good cell adhesion, enhanced alkaline phosphatase activity, and mineralization. A distal femoral condyle critical size defect in rabbits was used as a platform to confirm the effect of AG/NG–HA on bone regeneration in vivo. Our experiments show that the AG/NG–HA hybrid scaffolds provided a favorable environment for new bone formation. The results presented in this study suggest that the AG/NG–HA hybrid scaffolds have potential in bone-tissue regeneration engineering.

Three-dimensional honeycomb porous carbon (HPC) has attracted increasing attention in bioengineering due to excellent mechanical properties and a high surface-to-volume ratio. In this paper, a three-dimensional chitosan (CS)/honeycomb porous carbon/hydroxyapatite composite was prepared by nano-sized hydroxyapatite (nHA) on the HPC surface in situ deposition, dissolved in chitosan solution, and vacuum freeze-dried. The structure and composition of CS/HPC/nHA were characterized by scanning electron microscopy, transmission electron miscroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy, and the porosity, swelling ratio, and mechanical properties of the scaffold were also tested. The as-prepared scaffolds possess hierarchical pores and organic–inorganic components, which are similar in composition and structure to bone tissues. The synthesized composite scaffold has high porosity and a certain mechanical strength. By culturing mouse bone marrow mesenchymal stem cells on the surface of the scaffold, it was confirmed that the scaffold facilitated its growth and promoted its differentiation into the osteogenesis direction. In vivo experiments further demonstrate that the CS/HPC/nHA composite scaffold has a significant advantage in promoting bone formation in the bone defect area. All the results suggested that the CS/HPC/nHA scaffolds have great application prospect in bone tissue engineering.

Nanocomposite scaffold materials have shown great prospect in promoting bone integration and bone regeneration. A three-dimensional graphene oxide foam/polydimethylsiloxane/zinc silicate (GF/PDMS/ZS) scaffold for bone tissue engineering was synthesized via dip coating and hydrothermal synthesis processes, resulting in the interconnected macroporous structure. The scaffold was characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric (TG) analysis. The result showed that scaffolds exhibiting a porous characteristic had organic–inorganic components similar to natural bone tissue. Moreover, the scaffolds possessed suitable pore size, high porosity, and good mechanical properties. In vitro experiments with mouse bone marrow mesenchymal stem cells (mBMSCs) revealed that the composite scaffold not only has great biocompatibility but also has the ability to induce mBMSC proliferation and preferential osteogentic differentiation. Thereafter, the expression of critical genes, ALP, RUNX2, VEGFA, and OPN, was activated. In vivo analysis of critical bone defect in rabbits demonstrated superior bone formation in defect sites in the GF/PDMS/ZS scaffold group at 12 weeks of post implantation without no significant inflammatory response. All the results validated that the GF/PDMS/ZS scaffold is a promising alternative for applications in bone regeneration.

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