Bone defects caused by bone fractures and disease often need treatment with biomaterials. However, biomaterials with proper ionic components and beneficial osteo-/angio-stimulation ability for enhanced bone regeneration are still lacking. In this study, cobalt-doped hydroxyapatite (Co-HA) with different ratios of Co/Ca (Co/Ca molar ratios of 1%, 0.5%, 0.1%, 0.05%, and 0.01%) was synthesized by the hydrothermal method. The materials were chemically characterized and the biological responses of bone marrow stromal cells (BMSCs), after being cultured with different ratios of real-time Co-HA extracts, were systematically studied. The results of the study showed that cobalt was incorporated into the HA lattice by replacing some of the calcium groups. The synthetic Co-HA samples were well-crystallized with a typical apatite structure. The biological responses revealed that incorporating 0.1% of Co2+ into HA (marked as Co0.1HA) could significantly improve BMSCs proliferation and showed higher cell viability in comparison with other Co-HA samples. The Co2+ concentrations of around 0.9369ug/L should be provided for efficient activities of BMSCs. The results of Alizarin red staining indicated that the ionic products from Co0.1HA could stimulate osteogenic differentiation of BMSCs and showed better osteogenic activity than HA. Western blotting analysis and RT-PCR data showed that real-time extract of Co0.1HA could upregulate the expression of VEGF, HO-1, and OPN through the HIF-1α pathway. In summary, Co0.1HA possesses the ability to stimulate both osteogenic and angiogenic differentiation of BMSCs, indicating that it might be a promising biomaterial for bone tissue engineering.

Among various biomaterials employed for bone repair, composites with good biocompatibility and osteogenic ability had received increasing attention from biomedical applications. In this study, we doped selenium (Se) into hydroxyapatite (Se-HA) by the precipitation method, and prepared different amounts of Se-HA-loaded poly (amino acid)/Se-HA (PAA/Se-HA) composites (0, 10 wt%, 20 wt%, 30 wt%) by in-situ melting polycondensation. The physical and chemical properties of PAA/Se-HA composites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and their mechanical properties. XRD and FT-IR results showed that PAA/Se-HA composites contained characteristic peaks of PAA and Se-HA with amide linkage and HA structures. DSC and TGA results specified the PAA/Se-HA30 composite crystallization, melting, and maximum weight loss temperatures at 203.33 degrees C, 162.54 degrees C, and 468.92 degrees C, respectively, which implied good thermal stability. SEM results showed that Se-HA was uniformly dispersed in PAA. The mechanical properties of PAA/Se-HA30 composites included bending, compressive, and yield strengths at 83.07 +/- 0.57, 106.56 +/- 0.46, and 99.17 +/- 1.11 MPa, respectively. The cellular responses of PAA/Se-HA composites in vitro were studied using bone marrow mesenchymal stem cells (BMSCs) by cell counting kit-8 assay, and results showed that PAA/Se-HA30 composites significantly promoted the proliferation of BMSCs at the concentration of 2 mg ml-1. The alkaline phosphatase activity (ALP) and alizarin red staining results showed that the introduction of Se-HA into PAA enhanced ALP activity and formation of calcium nodule. Western blotting and Real-time polymerase chain reaction results showed that the introduction of Se-HA into PAA could promoted the expression of osteogenic-related proteins and mRNA (integrin-binding sialoprotein, osteopontin, runt-related transcription factor 2 and Osterix) in BMSCs. A muscle defect at the back and a bone defect at the femoral condyle of New Zealand white rabbits were introduced for evaluating the enhancement of bone regeneration of PAA and PAA/Se-HA30 composites. The implantation of muscle tissue revealed good biocompatibility of PAA and PAA/Se-HA30 composites. The implantation of bone defect showed that PAA/Se-HA30 composites enhanced bone formation at the defect site (8 weeks), exhibiting good bone conductivity. Therefore, the PAA-based composite was a promising candidate material for bone tissue regeneration.

开放性骨折、关节炎(OA)和骨质疏松(OP)等疾病所导致的骨缺损修复术后抗感染已成为临床治疗上的一个难题.骨科围手术期大量应用抗生素易导致细菌耐药并加重患者的经济负担,因此开发非抗生素途径的抗菌骨修复材料是国内外众多科学家的追求与愿景.目前,非负载抗生素的骨修复材料主要有复合无机抗菌剂、复合有机抗菌剂和仿生纳米结构表面抗菌剂三类.现从抗菌作用、生物相容性和各自优缺点对上述三类骨修复材料进行综述,以期为开发新型具有抗菌和成骨作用的多功能骨修复材料提供新思路.

Bacterial infection caused by medical material is a common problem in the field of medicine. In this work, we aim to develop a novel antimicrobial bioplastic with potential medical value. A novel composite material composed of polyamino acid (PAA) and titanium dioxide/silver nanoparticles (TiO2/Ag NPs) was synthesized by in situ melting polycondensation with different TiO2/Ag loadings. The morphological, antibacterial, mechanical, thermal, and cytotoxicity properties of the PAA/TiO2/Ag composites were investigated. The results showed that uniform nanocomposites with amide bonds were synthesized, and the nanocomposites with 10% TiO2/Ag incorporation exhibited the best thermal and mechanical properties. Cytotoxicity assay showed that the composites significantly promoted the proliferation of MG-63 cells. The composites showed obvious inhibitory effect on both Escherichia coli and Staphylococcus aureus, and this effect was increased as the TiO2/Ag NPs doping was increased. These PAA/TiO2/Ag composites are suitable for antibacterial and high-performance biomaterials in the medical field.