Microstructure of Bioglass/Hydroxynpatite Coatings on Ti Substrate

Composite coatings of bioglass and hydroxyapatite (briefly named HA/BG) with different hydroxyapatite contents on titanium substrate were successfully fabricated. The fabricated coatings are characterized by rough and poriform surface.The densities of the coatings decrease with the increase of HA content. There is a transition layer with a 5 μm thickness between the BG coating and the substrate. During heat-treatment, hydroxyapatite crystals with hexastyle shape have precipitated from the BG.

Osteoblastic and anti-osteoclastic activities of strontium-substituted silicocarnotite ceramics: In vitro and in vivo studies

Osteoporosis bone defect is a refractory orthopaedic disease which characterized by impaired bone quality and bone regeneration capacity.Current therapies,including antiosteoporosis drugs and artificial bone grafts,are not always satisfactory.Herein,a strontium-substituted calcium phosphate silicate bioactive ceramic(Sr-CPS)was fabricated.In the present study,the extracts of Sr-CPS were prepared for in vitro study and Sr-CPS scaffolds were used for in vivo study.The cytocompatibility,osteogenic and osteoclastogenic properties of Sr-CPS extracts were characterized in comparison to CPS.Molecular mechanisms were also evaluated by Western blot.Sr-CPS extracts were found to promote osteogenesis by upregulating Wnt/β-catenin signal pathways and inhibit osteoclastogenesis through downregulating NF-κB signal pathway.In vivo,micro-CT,histological and histomorphometric observation were conducted after 8 weeks of implantation to evaluate the bone formation using calvarial defects model in ovariectomized rats.Compared with CPS,Sr-CPS significantly promoted critical sized ovariectomy(OVX)calvarial defects healing.Among all the samples,Sr-10 showed the best performance due to a perfect match of bone formation and scaffold degradation rates.Overall,the present study demonstrated that Sr-CPS ceramic can dually modulate both bone formation and resorption,which might be a promising candidate for the reconstruction of osteoporotic bone defect.

Double-edged effects caused by magnesium ions and alkaline environment regulate bioactivities of magnesium-incorporated silicocarnotite in vitro

Magnesium(Mg)is an important element for its enhanced osteogenic and angiogenic properties in vitro and in vivo,however,the inherent alkalinity is the adverse factor that needs further attention.In order to study the role of alkalinity in regulating osteogenesis and angiogenesis in vitro,magnesium-silicocarnotite[Mg-Ca5(PO4)2SiO4,Mg-CPS]was designed and fabricated.In this study,Mg-CPS showed better osteogenic and angiogenic properties than CPS within 10wt.%magnesium oxide(MgO),since the adversity of alkaline condition was covered by the benefits of improved Mg ion concentrations through activating Smad2/3-Runx2 signaling pathway in MC3T3-E1 cells and PI3K-AKT signaling pathway in human umbilical vein endothelial cells in vitro.Besides,provided that MgO was incorporated with 15wt.%in CPS,the bioactivities had declined due to the environment consisting of higher-concentrated Mg ions,stronger alkalinity and lower Ca/P/Si ions caused.According to the results,it indicated that bioactivities of Mg-CPS in vitro were regulated by the double-edged effects,which were the consequence of Mg ions and alkaline environment combined.Therefore,if MgO is properly incorporated in CPS,the improved bioactivities could cover alkaline adversity,making Mg-CPS bioceramics promising in orthopedic clinical application for its enhancement of osteogenesis and angiogenesis in vitro.

Advanced protein adsorption properties of a novel silicate-based bioceramic: A proteomic analysis

Silicate bioceramics have been shown to possess excellent cytocompatibility and osteogenic activity,but the exact mechanism is still unclear.Protein adsorption is the first event taking place at the biomaterial-tissue interface,which is vital to the subsequent cellular behavior and further influence the biomaterial-tissue interaction.In this work,the protein adsorption behavior of a novel CPS bioceramic was evaluated using the proteomics technology.The results showed that CPS adsorbed more amount and types of serum proteins than HA.FN1 and IGF1 proteins selected from proteomics results were validated by Western-blot experiment.Pathway analysis also revealed mechanistic insights how these absorbed proteins by CPS help mediate cell adhesion and promotes osteogenic activity.Firstly,the dramatically enhanced adsorption of FN1 could greatly promote cell adhesion and growth.Secondly,IGF1 was uniquely adsorbed on CPS bioceramic and IGF1 could activate Rap1 signaling pathway to promote cell adhesion.Thirdly,the increased adsorption of FN1,IGF1 and COL1A2 proteins on CPS explains its better ability on bone regeneration than HA.Fourthly,the increased adsorption of IGF1,CHAD,COL2A1 and THBS4 proteins on CPS explains its ability on cartilage formation.Lastly,the increased adsorption of immunological related proteins on CPS may also play a positive role in bone regeneration.In addition,CPS had a much better cell adhesion ability than HA,proving that more adsorbed proteins really had a positive effect on cell behavior.The more adsorbed proteins on CPS than HA might indicated a better bone regeneration rate at early stage of implantation.

Optimized sintering and mechanical properties of Y-TZP ceramics for dental restorations by adding lithium disilicate glass ceramics

The novel dental ceramics can be fabricated at lower temperatures when sol-gel derived lithium disilicate glass ceramics(LDGC)was used as an additive for yttria stabilized tetragonal zirconia polycrystalline(Y-TZP)ceramics.The effect of LDGC on the sintering,mechanical,and translucent properties of Y-TZP ceramics was investigated in the present study.The results showed that the LDGC additive effectively improved the densification of Y-TZP at 1100℃,which was much lower than the sintering temperature for pure Y-TZP.When sintered at 1100℃,the Y-TZP with 1 wt%LDGC reached a relative density of 95.45%,and prossessed a flexural strength of 482.4 MPa and a fracture toughness of 5.94 MPa-m12.Moreover,its translucency was also improved.While,the addition of LDGC could result in an escape of yttrium atoms from the grain lattice of zirconia,which induced the tetragonal-monoclinic transformation of zirconia and abnormal growth of monoclinic grains.The escaped yttrium atoms diffused into the intergranular glass phase.The results indicated that the novel Y-TZP-LDGC ceramics has a great potential to be used for all-ceramic restorations.