Distinct mechanisms of iron and zinc metal ions on osteo-immunomodulation of silicocarnotite bioceramics.

The immunomodulatory of implants have drawn more and more attention these years. However, the immunomodulatory of different elements on the same biomaterials have been rarely investigated. In this work, two widely used biosafety elements, iron and zinc added silicocarnotite (Ca5(PO4)2SiO4, CPS) were applied to explore the routine of elements on immune response. The immune reactions over time of Fe-CPS and Zn-CPS were explored at genetic level and protein level, and the effects of their immune microenvironment with different time points on osteogenesis were also investigated in depth. The results confirmed that both Fe-CPS and Zn-CPS had favorable ability to secret anti-inflammatory cytokines. The immune microenvironment of Fe-CPS and Zn-CPS also could accelerate osteogenesis and osteogenic differentiation in vitro and in vivo. In terms of mechanism, RNA-seq analysis and Western-blot experiment revealed that PI3K-Akt signaling pathway and JAK-STAT signaling pathways were activated of Fe-CPS to promote macrophage polarization from M1 to M2, and its immune microenvironment induced osteogenic differentiation through the activation of Hippo signaling pathway. In comparison, Zn-CPS inhibited polarization of M1 macrophage via the up-regulation of Rap1 signaling pathway and complement and coagulation cascade pathway, while its osteogenic differentiation related pathway of immune environment was NF-κB signaling pathway.

Hydrogen sensing with Ni-doped TiO2 nanotubes.

Doping with other elements is one of the efficient ways to modify the physical and chemical properties of TiO2 nanomaterials. In the present work, Ni-doped TiO2 nanotubes were fabricated through anodic oxidation of NiTi alloy and further annealing treatment. The hydrogen sensing properties of the nanotube sensor were investigated. It was found that the Ni-doped TiO2 nanotubes were sensitive to an atmosphere of 1,000 ppm hydrogen, showing a good response at both room temperature and elevated temperatures. A First-Principle simulation revealed that, in comparison with pure anatase TiO2 oxide, Ni doping in the TiO2 oxide could result in a decreased bandgap. When the oxide sensor adsorbed a certain amount of hydrogen the bandgap increased and the acceptor impurity levels was generated, which resulted in a change of the sensor resistance.

Realizing Both Antibacterial Activity and Cytocompatibility in Silicocarnotite Bioceramic via Germanium Incorporation.

The treatment of infective or potentially infectious bone defects is a critical problem in the orthopedic clinic. Since bacterial activity and cytocompatibility are always contrary factors, it is hard to have them both in one material. The development of bioactive materials with a good bacterial character and without sacrificing biocompatibility and osteogenic activity, is an interesting and valuable research topic. In the present work, the antimicrobial characteristic of germanium, GeO2 was used to enhance the antibacterial properties of silicocarnotite (Ca5(PO4)2SiO4, CPS). In addition, its cytocompatibility was also investigated. The results demonstrated that Ge-CPS can effectively inhibit the proliferation of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and it showed no cytotoxicity to rat bone marrow-derived mesenchymal stem cells (rBMSCs). In addition, as the bioceramic degraded, a sustainable release of germanium could be achieved, ensuring long-term antibacterial activity. The results indicated that Ge-CPS has excellent antibacterial activity compared with pure CPS, while no obvious cytotoxicity was observed, which could make it a promising candidate for the bone repair of infected bone defects.

Calcium Phosphate Silicate Microspheres with Soybean Lecithin as a Sustained-Release Bone Morphogenetic Protein-Delivery System for Bone Tissue Regeneration.

Bone morphogenetic protein (BMP) is a growth factor that effectively promotes osteogenesis. Microsphere-based drug-delivery systems can facilitate an increase in the local concentration of BMP, thus promoting bone formation. In this study, calcium phosphate silicate (CPS) microspheres were used as drug-loading systems for BMP. Three groups─CPS, CPS + BMP, and CPS + BMP + soy lecithin (SL)─were set up, where SL was used to prolong the osteogenic effect of the microsphere system. Bone marrow mesenchymal stem cells and femoral defects in rats were used to compare the osteogenic ability of the three groups. The results indicated that CPS microspheres were good carriers of BMP, facilitating a smoother release into the cells and tissues. SL loading improved the loading rate of BMP, which promoted the osteogenic effect of the microspheres with BMP. We propose CPS microspheres as potential drug-delivery systems that can be effectively used in the treatment of bone defects.

Wide-range hydrogen sensing with Nb-doped TiO2 nanotubes.

Anatase-type titania nanotubes doped with Nb element were fabricated through an anodization of Ti35Nb alloy substrate and further annealing at 450 °C. Hydrogen sensitivity of the Nb-doped TiO(2) nanotubes at room temperature was investigated through exposure of the nanotube samples to different hydrogen atmospheres. At room temperature, the Nb-doped nanotubes demonstrated a good sensitivity for wide-range detection of both dilute and high-concentration hydrogen atmospheres ranging from 50 ppm to 2% H(2). The Nb-doped nanotubes also presented remarkable reversibility and repeatability as well as a quick response to the hydrogen atmosphere. The Nb-doped titania nanotubes have great advantages as robust and wide-range hydrogen sensors operating at room temperature.

Evaluation of osteoinduction and proliferation on nano-Sr-HAP: a novel orthopedic biomaterial for bone tissue regeneration.

Hydroxyapatite (HAP), a CaP compound similar to the mineral phase present in bone, has excellent biocompatibility but little osseous inductivity. In this study, we evaluated the novel nano-Sr-HAP, in which the calcium of hydroxyapatite was substituted with strontium, which acts as a bone-forming agent. Its biocompatibility and osteoinduction were assayed using marrow mesenchymal stem cells (MSCs) and osteoblasts (OBs) in vitro. We were able to demonstrate that nano-Sr-HAP supported increased OB cell adhesion, proliferation and viability up to 4 days in culture when compared with nano-HAP. MSCs cultured with nano-Sr-HAP showed higher alkaline phosphatase (ALP) activity. More extracellular mineralized nodules were found with nano-Sr-HAP compared to nano-HAP, especially in images of ALP staining. We suggest that nano-Sr-HAP powders possess osteoconductive and osteoinductive properties and have the potential to be used in the repair of bone defects caused by osteoporotic fractures.

Sol-gel preparation of ZrO2-Li2Si2O5 ceramics and their sintering properties.

Despite zirconia (ZrO2) ceramics and lithium disilicate (Li2Si2O5) glass-ceramics have been widely applied on the market for dental restorations, composites that can combine the advantages of both are still demanded. Here we introduced a ZrO2-Li2Si2O5 ceramic with minimized glass phases that fabricated through a sol-gel method and subsequent pressureless sintering. ZrO2-Li2Si2O5 powders were obtained after the gel precursors were heat treated under 800 °C. The gel-derived powders were molded and pressureless sintered under 900-1000 °C to investigate their sintering properties. From the microstructures of the sintered samples, we knew that the densification process was dominated by the growth of Li2Si2O5 grains instead of the growth of ZrO2 grains. Increasing in Li2Si2O5 content can promote ceramic densification. Interestingly, reactions between ZrO2 and Li2Si2O5 were observed with sintering temperature higher than 916 °C, which can increase the porosity of the ceramics. Therefore, both the content of Li2Si2O5 and sintering temperature should be well adjusted to achieve samples with desired properties. Finally, ceramics with flexural strength of 226 MPa and porosity of 0.4% were achieved from powders with moderate Li2Si2O5 content after sintering at 1000 °C.

Co-exchanged montmorillonite: a potential antibacterial agent with good antibacterial activity and cytocompatibility.

As a biocompatible material with rich resources and economic benefits, montmorillonite (MMT) has been widely used in the antibacterial field as a drug carrier and toxin adsorbent. In addition, the distinctive structure of MMT provides a possibility to tune its property in a wide range through ion-exchange. In this study, Co-montmorillonite (CoMMT) was prepared by the ion-exchanging method in a Co(NO3)2 solution and its antibacterial activity and cytocompatibility were investigated. The results showed that Co was introduced into MMT successfully and led to an increase in the interlayer spacing of MMT. Also, CoMMT showed a morphology of irregular aggregates consisting of stacked and intertwined lamellae with a uniform cobalt distribution. Besides, CoMMT had better dispersity and higher specific surface area than unmodified MMT. The antibacterial test results showed that CoMMT had good antibacterial activity against S. aureus and E. coli when the CoMMT concentration was higher than 0.2 mg mL-1 and 0.4 mg mL-1, respectively. The possible antibacterial mechanism of CoMMT was speculated and verified by a combination of SEM and EDS results. In addition, CoMMT showed no obvious cytotoxicity to MC3TC-E1 at the observed antibacterial concentration. These findings demonstrated that CoMMT with good biocompatibility and antibacterial activity could be used as a novel antibacterial agent for tissue engineering.

Favorable osteogenic activity of iron doped in silicocarnotite bioceramic: In vitro and in vivo Studies.

BACKGROUND: Calcium phosphate silicate (Ca5(PO4)2SiO4 or CPS) is a promising bioceramic for bone grafting. Iron (Fe) is a trace element in the human body that has been reported to enhance the mechanical strength of CPS ceramics. However, the exact biofunctions of Fe, combined with another human trace element, viz. silicon (Si), in CPS and the optimal dose for Fe addition must be further investigated. METHODS: In vitro: the morphology, structure and cell adhesion were observed by SEM; the ability to promote osteogenic differentiation and mineralization was explored by ALP and alizarin red staining; the expression of osteogenic-specific genes and proteins was detected by PCR, WB and immunofluorescence. In vivo: Further exploration of bone regeneration capacity by establishing a skull defect model. RESULTS: In vitro, we observed increased content of adhesion-related proteins and osteogenic-related genes expression of Fe-CPS compared with CPS, as demonstrated by immunofluorescence and polymerase chain reaction experiments, respectively. In vivo micro-computed tomography images, histomorphology, and undecalcified bone slicing also showed improved osteogenic ability of Fe-CPS bioceramics. CONCLUSION: With the addition of Fe2O3, the new bone formation rate of the Fe-CPS scaffold after 12 weeks increased from 9.42% to 43.76%. Moreover, both in vitro and in vivo experimental outcomes indicated that Fe addition improved the CPS bioceramics in terms of their osteogenic ability by promoting the expression of osteogenic-related genes. Fe-CPS bioceramics can be employed as a novel material for bone tissue engineering on account of their outstanding new bone formation ability. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: This study suggests that Fe-CPS bioceramics can be employed as a novel material for bone tissue engineering on account of their outstanding new bone formation ability,which provides promising therapeutic implants and strategies for the treatment of large segmental bone defects.

Osteoimmune reaction caused by a novel silicocarnotite bioceramic promoting osteogenesis through the MAPK pathway.

The host immune response to an implant is a key factor in determining the fate of bone grafts, which is thought to be a regulator of tissue regeneration. Figuring out the effects of the osteoimmune microenvironment on the osteogenesis of bone grafts can be a valuable strategy for their design and can further enhance the healing of bone defects. Our previous study demonstrated that the silicocarnotite (Ca5(PO4)2SiO4, CPS) bioceramic can significantly promote osteogenesis. The aim of this study is to investigate the immune reaction of CPS, the effects of the immune microenvironment on osteogenesis, and the related molecular mechanisms. Compared to hydroxyapatite (Ca10(PO4)6(OH)2, HA), the results showed that CPS could downregulate the pro-inflammatory phenotype and upregulate the anti-inflammatory phenotype, showing the lower levels of TNF-α and increased expression of IL-10. We further found that CPS could regulate the expression of NPPA, EDN1, and MMP9 in RAW 264.7 by RNA sequencing, which may be related to its superiority in osteogenesis. The osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) was subsequently studied in a macrophage-conditioned medium pretreated with CPS, and the medium caused a significant promotion of the osteogenic differentiation of rBMSCs, demonstrating that CPS can generate a favorable immune microenvironment to promote rBMSCs differentiation. In terms of mechanism, CPS in the macrophage-conditioned medium promoted osteogenic differentiation through the MAPK pathway, including ERK1/2, JNK and P38. Our study demonstrated that osteogenic differentiation was influenced by the immune microenvironment generated via the implant, and also presented an effective tool for studying the mechanisms of macrophage polarization as well as functions.

Interactive effects of cerium and copper to tune the microstructure of silicocarnotite bioceramics towards enhanced bioactivity and good biosafety.

Endowing biomaterials with functional elements enhances their biological properties effectively. However, improving bioactivity and biosafety simultaneously is still highly desirable. Herein, cerium (Ce) and copper (Cu) are incorporated into silicocarnotite (CPS) to modulate the constitution and microstructure for degradability, bioactivity and biosafety regulation. Our results demonstrated that introducing Ce suppressed scaffold degradation, while, co-incorporation of both Ce and Cu accelerated degradability. Osteogenic effect of CPS in vitro was promoted by Ce and optimized by Cu, and Ce-induced angiogenic inhibition could be mitigated by cell coculture method and reversed by Ce-Cu co-incorporation. Ce enhanced osteogenic and angiogenic properties of CPS in a dose-dependent manner in vivo, and Cu-Ce coexistence exhibited optimal bioactivity and satisfactory biosafety. This work demonstrated that coculture in vitro was more appropriately reflecting the behavior of implanted biomaterials in vivo. Interactive effects of multi-metal elements were promising to enhance bioactivity and biosafety concurrently. The present work provided a promising biomaterial for bone repair and regeneration, and offered a comprehensive strategy to design new biomaterials which aimed at adjustable degradation behavior, and enhanced bioactivity and biosafety.

Study on antibacterial and fluoride-releasing properties of a novel composite resin with fluorine-doped nano-zirconia fillers.

OBJECTIVE: A novel composite resin (CR) with fluorine-doped nano-zirconia (F-ZrO2) fillers was developed as an antibacterial restorative material. This article described the synthesis and investigated the fluoride release, antibacterial property and cytotoxicity of the novel CR. METHODS: F-ZrO2 powders with different fluorine contents (0% F-ZrO2, 5% F-ZrO2, 10% F-ZrO2 or 20% F-ZrO2) were synthesized by chemical precipitation method and characterized by XRD, SEM and TEM-EDS. The content and release of fluoride were also determined. 20% F-ZrO2 powers were selected to develop the novel CRs (FZ-25, FZ-50, and FZ-75). The fluoride release from the novel CRs during 28 days was recorded. The antibacterial property of the novel CRs was investigated with direct contact test (DCT) and metabolic activity test (CCK8). The cytotoxicity of the CRs was also evaluated here. RESULTS: F-ZrO2 powders with different fluorine contents were obtained. The fluoride release increased with increasing of the fluoride content. Through the antibacterial performance evaluation, 20% F-ZrO2 powders, which exhibiting the best antibacterial property, were selected as the fillers for preparing the novel CR. The novel CR with F-ZrO2 fillers exhibited an effective antibacterial effect. Compared with the control group, the antibacterial rates of FZ-25, FZ-50 and FZ-75 were 51.65%, 54.14% and 66.80% (p<0.05), respectively. No obvious cytotoxicity of the novel CR was detected in this study. CLINICAL SIGNIFICANCE: The novel CR with continuous fluoride release and proper antibacterial property is expected to be used as an antibacterial material to reduce secondary caries.

Fabrication of enamel-like structure on polymer-infiltrated zirconia ceramics.

OBJECTIVES: The aim of this study is to improve the biological and mechanical properties of zirconia-based PICN (polymer-infiltrated-ceramic-network) materials by fabrication an enamel-like structure on its surface. METHODS: Fluorapatite (FA) arrays were fabricated on zirconia discs by hydrothermal treatment. After polymer infiltration, an enamel-like structure was obtained on zirconia-based PICN materials. Effects of hydrothermal treatment conditions on the FA arrays were investigated by XRD, FTIR and SEM. Human gingival fibroblast cells (HGFs) and Escherichia coli (E. coli) were used to evaluate the cytocompatibility and antibacterial properties. Nanoindentation method was employed to determine elastic modulus and hardness. RESULTS: A facile and pervasive method was developed in this study to fabricate an enamel-like structure constituted of controlled FA arrays and interstitial resin on zirconia-based PICN materials. The obtained FA arrays can significantly promote the adhesion and proliferation of human gingival fibroblasts (HGFs), and further effectively inhibit the growth of Escherichia coli. Owing to the hierarchical structure, the enamel-like structure has achieved a hardness of 1.79 GPa and a lower Young's modulus of 37.4 GPa. SIGNIFICANCES: The enamel-like structure, with excellent biological and mechanical properties, is promising for various applications in dentistry.

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.

Copper containing silicocarnotite bioceramic with improved mechanical strength and antibacterial activity.

Copper is well known for its multifunctional biological effects including antibacterial and angiogenic activities, while silicon-containing bioceramic has proved to possess superior biological properties to hydroxyapatite (HA). In this work, CuO was introduced to silicocarnotite (Ca5(PO4)2SiO4, CPS) to simultaneously enhance its mechanical and antibacterial properties, and its cytocompatibility was also evaluated. Results showed that CuO could significantly facilitate the densification process of CPS bioceramic through liquid-phase sintering. The bending strength of CPS with the addition of 3.0 wt% CuO improved from 29.2 MPa to 63.4 MPa after sintered at 1200 °C. Moreover, Cu-CPS bioceramics demonstrated superior in vitro antibacterial property against both S. aureus and E. coli strains by destroying their membrane integrity, and the antibacterial activity augmented with CuO content. Meanwhile, the released Cu ions from Cu-CPS bioceramics could promote the proliferation of human umbilical vein endothelial cells (HUVECs), and the in vitro cytocompatibility exhibited concentration dependence on Cu ions. These suggest that Cu-CPS bioceramics might be promising candidates for bone tissue regeneration with an ability to prevent postoperative infections.

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

[This corrects the article DOI: 10.1093/rb/rbab016.].

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 10 wt.% 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 15 wt.% 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.

Complementary and synergistic effects on osteogenic and angiogenic properties of copper-incorporated silicocarnotite bioceramic: In vitro and in vivo studies.

Promoting bone regeneration to treat bone defects is a challenging problem in orthopedics, and developing novel biomaterials with both osteogenic and angiogenic activities is sought as a feasible solution. Here, copper-silicocarnotite [Cu-Ca5(PO4)2SiO4, Cu-CPS] was designed and fabricated. In this study, the Cu-CPS ceramics demonstrated better mechanical, osteogenic, and angiogenic properties in vitro and in vivo than pure CPS one. Particularly, CPS with 1.0 wt% CuO (1.0Cu-CPS) exhibited the best performance. Additionally, hydroxyapatite with 1.0 wt% CuO (1.0Cu-HA) was used to explore the respective effects of copper and silicon (Si). According to the in vitro results, it indicated that Cu enhanced the osteogenic activity of CPS ceramics although Si played a dominate role in the osteogenic process. Moreover, Cu could promote an early stage of angiogenesis, and the complementary effect of Si and Cu was found in the late phase. Furthermore, the in vivo results illustrated that the synergistic effect of Cu and Si improved bone and vessel regeneration during the degradation of Cu-CPS scaffolds (P < 0.05). Therefore, Cu-CPS ceramics could improve osteogenesis and angiogenesis through the simultaneous effects of Cu and Si, thus, offering a promising treatment option in orthopedic application for bone tissue regeneration.

Ferric oxide: A favorable additive to balance mechanical strength and biological activity of silicocarnotite bioceramic.

Ideal materials for bone regeneration should have not only a good bioactivity, but also a good mechanical strength to provide an initial support for new bone formation. How to get a balance between high mechanical property and good bioactivity is a challenging issue for bone regeneration materials. In the present work, a biocompatible additive Fe2O3 was selected to optimize the comprehensive properties of a novel calcium phosphate silicate (CPS) ceramic using a mechanical mixing method. The effects of Fe2O3 content on microstructure, bending strength, apatite formation ability and cytocompatibility of Fe-CPS bioceramics were investigated and the related mechanism was also discussed. The obtained Fe-CPS bioceramics showed enhanced mechanical and favorable bioactivity performances. Especially, the Fe-CPS bioceramic with 1.5 wt% Fe2O3 sintered at 1250 °C presented the highest bending strength of 91.9 MPa. While, Fe-CPS bioceramics still exhibited a good ability on apatite formation in simulated body fluid (SBF), and cytocompatibility test revealed that Fe-CPS bioceramics were favorable for cell adhesion and proliferation. All the results indicated that Fe-CPS bioceramics are promising candidate materials for bone regeneration at load bearing applications.

Improved cellular bioactivity by heparin immobilization on polycarbonate film via an aminolysis modification for potential tendon repair.

Tendon repair was an important part during tendon to bone healing. In the present study, heparin molecules were immobilized on the aminolyzed PCL surface to improve the cellular bioactivity for potential tendon repair. The effects of heparin immobilization on protein adsorption behavior and cellular bioactivity of NIH3T3 and ATDC5 cells were investigated. The results were shown as follows.