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A Sr-incorporated Na–Ti–O nano-network with a lateral pore size of 20–300 nm was developed on titanium (Ti) substrate using one-step alkali etching in a mixed solution of NaOH and Sr(OH)2. The pore size of coating increases with Sr content, implying the proper amount of Sr in the electrolyte accelerates nanowire aggregation. The Sr(OH)2 particle precipitation has no significant effect on the coating morphology. Moreover, biological experiments suggest the prepared coating exhibits good cytocompatibility, and the amount of Sr under 0.7 at.% has no noticeable promoting effect on the cytocompatibility. [ABSTRACT FROM AUTHOR]

We report on the influence of stirring of electrolyte (glycerol + H2O + NaCl) on anodic growth of Ni-Ti-O nanopores (NPs) on nearly equiatomic NiTi alloy at different applied voltages. The results show that anodization is a diffusion-controlled process. The stirring has little influence on the NP diameter, but shortens its length. High stirring speed of electrolyte yields high Ni content in the NPs, which is promising in electrocatalysis, biosensor, supercapacitor, and other related fields. [ABSTRACT FROM AUTHOR]

Abstract The present work investigated the effects of annealing on corrosion behavior, Ni2+ release, cytocompatibility, and antibacterial ability of nickel-titanium-oxygen (Ni-Ti-O) nanopores (NPs) anodically grown on nearly equiatomic NiTi alloy, aiming at optimizing annealing process to yield favorable comprehensive performance. The morphology and crystal structure of the NPs were characterized by scanning electron microscopy and X-ray diffraction respectively. It was found that when the annealing temperature was <600 °C, the NP layer could be well preserved on the substrate surface, and annealed at 400 °C led to the transformation of amorphous phase to anatase. Annealing at 200 °C significantly enhanced the corrosion resistance and at 400 °C drastically reduced Ni2+ release of the NiTi alloy, but their cytocompatibility had no appreciable difference, indicating the release level of Ni2+ is well tolerated by osteoblasts. Although the release amount of Ni2+ is reduced after annealing especially the sample annealed at 400 °C, their antibacterial ability is even better when compared with that of the unannealed sample. These results suggest the NPs annealed as at 200–400 °C are promising as coatings of biomedical NiTi alloy. Highlights • Ni-Ti-O nanopores were anodically grown on nearly equiatomic NiTi alloy. • Annealing at 200–400 °C can well preserve the morphology of the nanopores on NiTi alloy. • Annealing at 200–400 °C can enhance the corrosion resistance and reduce Ni2+ release of the NiTi alloy. • Annealing at 200–400 °C can improve the antibacterial ability of the NiTi alloy without compromising their cytocompatibility. [ABSTRACT FROM AUTHOR]

In the present work, nickel-titanium-oxygen nanopores with different length (0.55–114 μm) were anodically grown on nearly equiatomic nickel-titanium (NiTi) alloy. Length-dependent corrosion behavior, nickel ion (Ni 2+ ) release, cytocompatibility, and antibacterial ability were investigated by electrochemical, analytical chemistry, and biological methods. The results show constructing nanoporous structure on the NiTi alloy improve its corrosion resistance. However, the anodized samples release more Ni 2+ than that of the bare NiTi alloy, suggesting chemical dissolution of the nanopores rather than electrochemical corrosion governs the Ni 2+ release. In addition, the Ni 2+ release amount increases with nanopore length. The anodized samples show good cytocompatibility when the nanopore length is <11 μm. Encouragingly, the length scale covers the one (1–11 μm) that the nanopores showing favorable antibacterial ability. Consequently, the nanopores with length in the range of 1–11 μm are promising as coatings of biomedical NiTi alloy for anti-infection, drug delivery, and other desirable applications. [ABSTRACT FROM AUTHOR]

The influence of electrolyte pH on anodic growth of Ni-Ti-O nanopores on NiTi alloy was investigated. Through manipulating HCl, NaCl, and NaOH concentrations in the electrolyte composed of 95 vol% ethylene glycol, 5 vol% H 2 O, and 0.15 M Cl − , the electrolyte pH was varied from 0.82 to 13.5. Although the pH has little influence on surface morphology and composition of the nanopores, it can significantly impact their growth rate. Initially, increase of the pH decreases the growth rate from 13.8 nm/s at pH = 0.82 to 5.7 nm/s at pH = 7.0. However, when the pH exceeds 7.0, its value increases with the pH and reaches up to 15.8 nm/s at pH = 13.5. The knowledge gained from this study should be valuable in the anodization of other valve metals and their alloys. [ABSTRACT FROM AUTHOR]

In the present work, we report the anodic growth of Ni-Ti-O nanopores (NPs) on NiTi alloy in ethylene glycol (EG) electrolyte containing H 2 O and NaBr. It is shown that the NPs with diameter concentrated at 50–60 nm can be grown at 10 V in EG electrolyte containing 5 vol% H 2 O and 0.48 M NaBr. The NP-coated NiTi alloy show lower corrosion current density compared with that of the bare NiTi alloy. In addition, the NPs possess good cytocompatibility and can even promote osteoblast spreading. Good corrosion resistance and cytocompatibility render the Ni-Ti-O NPs promising as coating of the NiTi alloy for biomedical applications. [ABSTRACT FROM AUTHOR]

Ni-Ti-O nanoporous film with pore diameters of 60–75 nm are produced anodically on NiTi in ethylene glycol containing 5–10 vol% H 2 O and 0.15–0.3 M NaCl at 10–20 V. The film fabricated in the NaCl-containing electrolyte are much thinner than those prepared in the HCl-containing electrolyte under similar experimental conditions, implying proper amount of H + in the electrolyte accelerates formation of the nanopores. Moreover, the experimental conditions to grow Ni-Ti-O nanoporous film on NiTi are not proper for pure Ti and Ni. The film of 1.9 μm in thickness exhibits good cytocompatibility thus is suitable for biomedical applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We report on a new electrolyte system to fabricate Ni-Ti-O nanopores with small diameter and high Ni content by anodizing nearly equiatomic NiTi alloy. In the electrolyte composed of ethylene glycol, 5 vol% H 2 O, and 0.23–0.9 wt% Na 2 CO 3 , uniform Ni-Ti-O nanopores with diameter of about 25 nm and Ni/Ti atomic ratio exceeding 0.30 can be anodically grown on the NiTi alloy under proper applied voltage (20–40 V). The small diameter (high specific surface area) and high Ni content enable the nanopores promising in electrochemical energy storage, electrocatalysis, gas/bio-sensing, and other emerging fields. [ABSTRACT FROM AUTHOR]

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 25 V. 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. [ABSTRACT FROM AUTHOR]

Anodization is used to fabricate Ni–Ti–O nanotube (NT) electrodes for non-enzymatic glucose detection. The morphology, microstructure and composition of the materials are characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Our results show amorphous and highly ordered NTs with diameter of 50 nm, length of 800 nm, and Ni/Ti ratio (at %) of 0.35 can be fabricated in ethylene glycol electrolyte supplemented with 0.2 wt.% NH 4 F and 0.5 vol.% H 2 O at 30 °C and 25 V for 1 h. Electrochemical experiments indicate that at an applied potential of 0.60 V vs. Ag/AgCl, the electrode exhibits a linear response window for glucose concentrations from 0.002 mM to 0.2 mM with a response time of 10 s, detection limit of 0.13 μM (S/N = 3), and sensitivity of 83 μA mM − 1 cm − 2 . The excellent performance of the electrode is attributed to its large specific area and fast electron transfer between the NT walls. The good electrochemical performance of the Ni–Ti–O NTs as well as their simple and low-cost preparation method make the strategy promising in non-enzymatic glucose detection. [ABSTRACT FROM AUTHOR]

A three‐dimensional metal‐organic framework named as [TbL(OH)2](COOH)3 ⋅ (solvent)x (Tb‐MOF), was successfully obtained by using Tb(NO3)3 ⋅ 6H2O and 1,1′,1′′‐(2,4,6‐trimethylbenzene‐1,3,5‐triyl)tris(methylene)‐tris(4‐carboxy‐pyridinium)tribromide (H3LBr3) as raw materials. A series of fluorescence detection experiments demonstrate that Tb‐MOF shows a fluorescence quenching effect on NB. Moreover, Tb‐MOF also exhibits a very fast fluorescence quenching response to trace Fe3+ ions, which is unaffected by the existence of other competitive metal cations. The linear curve between the fluorescence intensity of Tb‐MOF and the concentration of Fe3+ was plotted by the fluorescence titration experiments data. The calculated LOD for Fe3+ ions is 2.86×10−6 M. Therefore, based on the characteristics of Tb‐MOF, it can be regarded as a luminescent sensor for detecting NB and Fe3+. We have also explored the quenching mechanism of Tb‐MOF as a fluorescent sensing material. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 TiO 2 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract The present work reports on the hydrothermal synthesis of nanosheets on biomedical NiTi alloy in pure water. The results show rhombohedral NiTiO 3 nanosheets with thickness of 6 nm can be grown at 200 °C. Hydrothermal treatment enhances the corrosion resistance of the NiTi alloy. 30 min of the treatment significantly reduces Ni ion release, while prolonged hydrothermal time results in increased Ni ion release because of the growth of the nanosheets with large specific surface area. Excitingly, the nanosheets can well support cell growth, which suggests the release amount can be well tolerated. Good corrosion resistance and cytocompatibility combined with large specific surface area render the nanosheets promising as safe and efficient drug carriers of the biomedical NiTi alloy. Highlights • NiTiO 3 nanosheets were hydrothermally synthesized on NiTi alloy in pure water at 200 °C. • Hydrothermal treatment enhances the corrosion resistance of the NiTi alloy. • The nanosheets can well support cell growth. [ABSTRACT FROM AUTHOR]

Bacterial infection and loosening of orthopedic implants remain two disastrously postoperative complications. Angiogenesis is critical important to facilitate implant osseointegration in vivo . TiO 2 nanotubes arrays (NTAs) with proper dimensions possess good osseointegration ability. Accordingly, the present work incorporated copper (Cu) into TiO 2 NTAs (Cu-Ti-O NTAs) to enhance their antibacterial ability and angiogenesis activity, which was realized through anodizing magnetron-sputtered TiCu coatings with different Cu contents on pure titanium (Ti). Our results show ordered Cu-Ti-O NTAs can be produced under proper Cu content (< 15.14%) in TiCu coatings. The NTAs possess excellent long-term antibacterial ability against Staphylococcus aureus ( S. aureus ), which may be ascribed to sustained release of Cu 2 + . The cytotoxicity of Cu-Ti-O NTAs to endothelial cells (ECs) could be negligible and can even promote cell proliferation as revealed by live/dead staining and MTT. Meanwhile, Cu-Ti-O NTAs can up-regulate nitric oxide (NO) synthesis and vascular endothelial growth factors (VEGF) secretion of ECs on the sample surfaces compared with that of pure TiO 2 NTAs (control). Furthermore, the angiogenic activity is also enhanced in ionic extracts of Cu-Ti-O NTAs compared with the control. The excellent long-term antibacterial ability and favorable angiogenic activity render Cu-Ti-O NTAs to be promising implant coatings. [ABSTRACT FROM AUTHOR]

A two-step cyclic closed-die forging (CCDF), with the first step to enhance the formability and the second step to refine the matrix grain, was implemented on a solution-treated SiC/AZ91D nanocomposites. Results show that the initial coarse grain is refined from ∼105 μm to ∼27 μm after the implementation of CCDF at 400∘C, and further refined to ∼6.8 μm after another 6-pass of CCDF at 300∘C. Mg17Al12 precipitates are gradually crushed with the progress of CCDF and eventually evolve into small particles uniformly distributed within the matrix. SiC clusters are effectively dispersed into smaller clusters or single particle. Yield stress (YS) and ultimate tensile strength (UTS) of the SiC/AZ91D nanocomposites increase after 1 pass of CCDF at 300∘C, while the elongation to fracture decreases. With the progress of CCDF, YS, UTS and elongation to fracture exhibit a continual increase, reaching their maximum values of 196 MPa, 371 MPa and 9.2% after 6 passes of CCDF. [ABSTRACT FROM AUTHOR]

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, Na 2 Ti 3 O 7 /SrTiO 3 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 Na 2 Ti 3 O 7 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 SrTiO 3 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. • Na 2 Ti 3 O 7 /SrTiO 3 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. [ABSTRACT FROM AUTHOR]

• Ni-Ti-O nanopores can convert to nanospindles by hydrothermal treatment. • The hydrothermal conversion occurs at 200 °C in pure water. • The length and diameter are 70–110 nm and 16–24 nm, respectively. • The nanospindles can promote cell proliferation. The present work reports on the hydrothermal conversion of Ni-Ti-O nanopores anodically grown on NiTi alloy into nanospindles and their cytocompatibility. The results show the amorphous nanopores can transform to anatase nanospindles with length concentrated at 70–110 nm and diameter at 16–24 nm upon hydrothermal treatment at 200 °C in pure water for 2 h. The nanospindles also can promote proliferation of bone marrow mesenchymal stem cells when compared with that of nanopores and bare NiTi alloy thus are promising as biomedical coatings of NiTi alloy. [ABSTRACT FROM AUTHOR]

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 TiO 2 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. [ABSTRACT FROM AUTHOR]

Ni–Ti–O nanopores (NPs) free of irregular surface layers and with tunable diameters are prepared by anodizing NiTi alloy in glycerol containing H 2 O and NaCl. In an electrolyte composed of glycerol, 10 vol% H 2 O and 0.6 M NaCl, NPs with diameters between 23 and 39 nm can be produced at anodization voltages between 20 and 80 V. In this electrolyte system, the irregular oxide layer on the surface can be completely removed chemically and/or mechanically during anodization. The resulting Ni–Ti–O NPs with tunable diameters should prove useful, for example, in energy, environmental and biomedical applications. [ABSTRACT FROM AUTHOR]

Although long nanotubes with a large specific surface area are desirable in many applications, it is difficult to produce long Ni-Ti-O nanotubes on nearly equiatomic NiTi alloy in fluoride (F)-containing ethylene glycol (EG) by anodization. In this work, a new electrolyte composed of EG, H 2 O, and HCl is designed and adopted to fabricate long nanopores rather than nanotubes on the NiTi alloy. By applying an anodization voltage of 10 V to the EG solutions containing 5.0–11.0 vol% H 2 O and 0.125–0.75 M HCl, Ni-Ti-O nanopores with a diameter of about 70 nm are produced. The nanopore length increases almost linearly with anodization time and by optimizing the experimental conditions, nanopores with a length of 160 μm can be prepared. [ABSTRACT FROM AUTHOR]

Stent implantation has become one of the most widely used methods for the treatment of cardiovascular diseases. However, endothelial dysfunction and abnormal inflammatory response following implantation may lead to delayed re-endothelialization, resulting in vascular restenosis and stent thrombus. To address the concerns, we constructed nanospindles composed of TiO 2 and Ti 4 Ni 2 O through hydrothermal treatment of amorphous Ni-Ti-O nanopores anodically grown on NiTi alloy. The results show the treatment can significantly improve hydrophilicity and reduce Ni ion release, essentially independent of hydrothermal duration. The nanospindle surfaces not only promote the expression of endothelial functionality but also activate macrophages to induce a favorable immune response, downregulate pro-inflammatory M1 markers and upregulate pro-healing M2 markers. Moreover, nitric oxide (NO) synthesis, VEGF secretion, and migration of endothelial cells are enhanced after cultured in macrophage conditioned medium. The nanospindles thus are promising as vascular stent coatings to promote re-endothelization. [Display omitted] • The nanospindles can be fabricated by hydrothermal treatment of Ni-Ti-O nanopores. • Nanospindle surfaces directly upregulate EC functionality. • Nanospindle surfaces can upregulate EC functionality through immunomodulation. [ABSTRACT FROM AUTHOR]