•The Ni-Ti-O nanotubes (NTs) with similar surface properties but different Ni release levels are fabricated on NiTi alloy.•The NTs release more Ni than NiTi control but their cytocompatibility is ...comparable.•The NTs possess different Ni release levels but possess similar cytocompatibility.
To elucidate the relationship between Ni release and cytocompatibility of NiTi alloy, Ni-Ti-O nanotubes (NTs) are produced on its surface by anodization followed by annealing. The NiTi control has higher corrosion current density but releases less Ni than anodized samples, suggesting chemical dissolution of the NTs also contributes to Ni release. Although the annealed NTs release more Ni than that of NiTi control, they possess similar cytocompatibility. In addition, cytocompatibilitiy of the NTs with similar surface properties but have different Ni release levels is also comparable. These results suggest the amount of released Ni has little influence on the cytocompatibility.
In general, FeCrAl alloys are faced with the separation of the high-chromium solid solution into α and α′ phases. For the Fe-25Cr-5Al-RE alloy, it is imperative to investigate the structure and ...morphology and their effect on the alloy’s mechanical properties. In this paper, XRD is used to reveal the presence of α and α′ phases. Based on XRD data, Rietveld refinement combined with quantitative texture analysis is carried out to determine the lattice constants and the harmonic coefficients. Then, SEM and TEM techniques are employed to provide an insight into the α′ phase and its morphology. The percentage total elongation at fracture is anti-correlated with the lattice of the α′ phase and the generalized harmonic coefficients C41.
Engineering stability control of microstructure evolution and precision forming is a key technical issue for the high-performance manufacturing of magnesium alloy components. In this paper, a ...fine-grain processing window was proposed for the workability optimization and microstructure control of AZ80 magnesium alloy. The hot activation energy map (AEM) and processing map (PM) were established to analyze the hot-working properties and microstructural mechanisms, respectively. The internal state variable (ISV) based finite element (FE) model was introduced to predict the evolutions of grain size and microstructure homogeneity with processing parameters during multi-angular extrusion process. The fine-grain processing window was used to form a magnesium alloy plate. Fine microstructure and good forming performance were obtained with the optimized processing parameters at the complete DRX domain. Forming at the processing instability domain exhibited flow defects and microstructure heterogeneity. The above research can be applied to the processing parameter optimization and microstructure regulation during hot forming processes of magnesium alloy.
A multifaceted coating for hard tissue implants, with favorable osteogenesis, angiogenesis, and osteoimmunomodulation abilities, would be of great value since it could improve osseointegration and ...alleviate prosthesis loosening. However, to date there are few coatings that fully satisfy these criteria. Herein we describe a microporous TiO2 coating decorated with hydroxyapatite (HA) nanoparticles that is generated by micro-arc oxidation of pure titanium (Ti) and followed annealing. By altering the annealing temperature, it is possible to simultaneously tune the coating's physical (morphology and wettability) and chemical (composites and crystallinity) properties. A coating produced with micro-arc oxidization (MAO) with an annealing temperature of 650 °C (MAO-650) exhibits numerous favorable physicochemical properties, such as hybrid micro-nano morphology, superhydrophilicity, and highly crystalline HA nanoparticles. In vitro experiments reveal that the MAO-650 coating not only supports proliferation and differentiation of both osteoblasts and endothelial cells, but also inhibits the inflammatory response of macrophages and enables a favorable osteoimmunomodulation to facilitate osteo/angio-genesis. In vivo evaluation mirrors these results, and shows that the MAO-650 coating results in ameliorative osseointegration when compared with the pristine MAO coating. These data highlight the profound effect of surface physicochemical properties on the regulation of osteo/angio-genesis and osteoimmunomodulation in the enhancement of osseointegration.
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X-ray powder diffraction (XRPD) profiles provide valuable information on the geometrical shape of crystallites. This work delves into the complexity of determining the geometrical shape of ...crystallites, including plate-like and spherical TiO2 specimens, and discusses crucial parameters of edge length, shape coefficient, and orientation vector. The analysis demonstrates the necessity of using both line-broadening analysis and preferred orientation to elucidate the underlying physics of XRPD analysis. The choice of empirical formula is illustrated in analyzing plate-like crystallites with the characteristic of flat morphology. For spherical crystallites, the March-Dollase formula is recommended.
•X-ray diffraction powder profiles are used to determining crystallite morphology.•Crystallite shape with edge length (L), shape coefficient (η), and orientation UVW.•The integration of line-broadening analysis and preferred orientation provides insights into crystallite shape.
Titanium (Ti) is widely used in the field of hard tissue implant materials due to its desirable mechanical properties and biocompatibility, but its osteogenic activity is relatively poor, hindering ...its clinical applications. In this work, Na-Ti-O nanostructured film was prepared on Ti surface by anodization in 2 M NaOH electrolyte at different applied voltages. The results show that uniform film can be formed when the voltage is between 15 and 25 V. Compared with untreated Ti, the anodized samples can promote osteoblast spreading, proliferation, and osteogenic differentiation. These results indicate Na-Ti-O nanostructured film is promising to functionalize Ti-based materials for dental and orthopedic applications.
•Na-Ti-O nanostructured film was anodically grown on titanium surface in NaOH electrolyte.•The film could be grown at applied voltage of 15–25 V with the NaOH concentration of 2 M.•The film could promote osteoblast spreading, proliferation, and osteogenic differentiation.
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Coating materials applied for intraosseous implants must be optimized to stimulate osseointegration. Osseointegration is a temporal and spatial physiological process that not only ...requires interactions between osteogenesis and angiogenesis but also necessitates a favorable immune microenvironment. It is now well-documented that hierarchical nano-micro surface structures promote the long-term stability of implants, the interactions between nano-micro structure and the immune response are largely unknown. Here, we report the effects of microporous titanium (Ti) surfaces coated with nano-hydroxyapatite (HA) produced by micro-arc oxidation and steam-hydrothermal treatment (SHT) on multiple cell behavior and osseointegration. By altering the processing time of SHT it was possible to shift HA structures from nano-particles to nano-rods on the microporous Ti surfaces. Ti surfaces coated with HA nano-particles were found to modulate the inflammatory response resulting in an osteoimmune microenvironment more favorable for osteo-/angio-genesis, most likely via the activation of certain key signaling pathways (TGF-β, OPG/RANKL, and VEGF). By contrast, Ti surfaces coated with nano-rod shaped HA particles had a negative impact on osteo-/angio-genesis and osteoimmunomodulation. In vivo results further demonstrated that Ti implant surfaces decorated with HA nano-particles can stimulate new bone formation and osseointegration with enhanced interaction between osteocytes and implant surfaces. This study demonstrated that Ti implants with micro-surfaces coated with nano-particle shaped HA have a positive impact on osseointegration.
Osteo-/angio-genesis are of importance during osteointegration of the implants. Recent advances unravel that immune response of macrophages and its manipulated osteoimmunomodulation also exerts a pivotal role to determine the fate of the implant. Surface nano-micro modification has evidenced to be efficient to influence osteogenesis, however, little is known links nano-microstructured surface to immune response, as well the osteoimmunomodulation. This study demonstrates that the nano-particles decorated micro-surface, compared with the nano-rods decorated micro-surface enables osteogenesis and angiogenesis concurrently that has not been investigated previously. This study also unravels that the immune response of macrophages can be manipulated by the nano-micro surface, especially the nano-dimension matters, leading to a differential effect on osteointegration. The additional knowledge obtained from this study may provide foundation and reference for future design of the coating materials for implantable materials.
•We fabricated Ni–Ti–O nanotubes (NTs) with different size on NiTi alloy through varying anodization voltages.•Worse corrosion resistance and more Ni release are observed from large ...NTs.•Cytocompatibility of NiTi alloy is improved after anodization especially for the sample anodized at 25V.
We fabricate Ni–Ti–O NTs with different size on NiTi alloy through varying anodization voltages and evaluate their corrosion behavior, Ni release, and cytocompatibility. Our results show the NTs influence the corrosion behavior and cytocompatibility of NiTi alloy in a size-dependent manner. Worse corrosion resistance and more Ni release are observed from large NTs because of their high specific surface area. However, cytocompatibility is improved after anodization especially for the sample anodized at 25V. These results thus indicate the release level of Ni ions from NiTi alloy is well tolerated by osteoblasts and surface nanotubular structure contribute to its cytocompatibility.
Favorable osteogenic activity and antibacterial ability are highly desired for hard tissue repair and replacement materials. However, as a typical implant material, nearly equiatomic nickel‑titanium ...(NiTi) alloy exhibits poor osteogenic and antibacterial capacities despite its good biocompatibility and unique mechanical properties. In this work, nickel‑titanium‑oxygen (Ni-Ti-O) nanopores (NPs) coatings incorporated with magnesium (NP-Mg) are fabricated on the NiTi alloy by anodization and hydrothermal treatment (HT). The results show the amount of loaded Mg can be regulated by the NPs length (1.8 and 10.4 μm) and the hydrothermal duration (1 and 5 h). In addition, the surface morphology of the coatings transform to nanosheets after HT for 1 h and to NPs with small diameter after HT for 5 h. Bone marrow mesenchymal stem cells (BMSCs) cultured on NP-Mg-coated NiTi alloy show better proliferation and osteogenic differentiation than that of pristine and as-anodized specimens. Antibacterial experiments show although HT reduces Ni ion release and increase corrosion resistance, the NP-Mg coatings yet maintain potent antibacterial activity especially against adherent bacteria. The NPs coating with thickness of 10.4 μm and HT for 5 h shows favorable osteogenic activity, antibacterial ability, little Ni ion release, and good corrosion resistance thus is a promising candidate to functionalize the surface of the NiTi alloy for orthopedic applications.
•Mg has been successfully incorporated into Ni-Ti-O nanopore layers on NiTi alloy.•The layers show favorable osteogenic ability because of Mg2+ release and nanoporous structure.•The layers can release Ni2+ and Mg2+ to kill bacteria.
Titanium (Ti) and its alloys have been widely adopted as implant materials due to their satisfactory biocompatibility and favorable mechanical property. However, they usually show poor osteogenic ...ability, hindering its clinical application. Herein, Na2Ti3O7/SrTiO3 hybrid coatings on Ti were fabricated via one-step alkali etching in a mixed solution of NaOH and Sr(OH)2 to enhance its osteogenic activity. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy were used to characterize the samples. Biological experiments were conducted to evaluate their osteogenic activity. The results showed Na2Ti3O7 nanowire coatings could be grown on Ti surface and Sr could be incorporated into the coatings. Incorporation of Sr clustered the nanowires and high Sr content lead to the formation of spherical SrTiO3 with diameter of about 1 μm. Sr2+ could continuously release from the samples and the release amount increased with Sr content in the coatings. Although adhesion, spreading, viability and proliferation of osteoblasts on all the samples had no significant difference when compared with Sr-free one, they could significantly promote osteogenic differentiation as verified by enhanced alkaline phosphatase (ALP) activity, collagen secretion, and extracellular matrix mineralization of osteoblasts. Further studies depicted that the expression levels of osteogenic-related genes including ALP, type I collagen and transforming growth factor-β were significantly upregulated in Sr-containing samples. The desirable osteogenic capacity may be ascribed to the synergistic effect of continuous Sr2+ release and nanostructured morphology. The samples containing Sr of 5.65–11.07 at.% showed the best osteogenic capacity therefore possess great potential in hard-tissue implant field.
•Na2Ti3O7/SrTiO3 hybrid coatings were fabricated on titanium by alkali treatment.•The coatings can continuously release Sr2+.•Sr2+ release and nanostructure can promote osteogenic differentiation of osteoblasts.
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