Titania Nanotube Arrays Research Articles

Optimized titanium dioxide nanotubes for dental implants: Estimation of mechanical properties and effects on the biological behaviors of human gingival fibroblasts and oral bacteria

The long-term successes of implant restorations rely on both appropriate osseointegration and robust soft tissue integration (STI). Numerous studies have reported that titanium dioxide nanotube (TNT) arrays formed by electrochemical anodization (EA) can promote early osteogenesis, but the mechanical stability of such modifications is often ignored and remains underexplored. In addition, relatively little research has been done on their effects on soft tissues integration. In this study, we developed mechanically robust TNT arrays using an optimized EA system. Subsequently, we immobilized a peptide, specifically D-amino K122-4, onto the anodized TNTs via polydopamine (PDA) films to enhance their mechanical properties. Surface morphology and composition were characterized by scanning electron microscopy (SEM), atomic force microscopy, and X-ray photoelectron spectroscopy. Mechanical properties, including the elastic modulus and hardness of TNTs modified Ti surfaces, were assessed using the nano-indention test. The adhesive strength of TNTs films to the substrate was measured using the nano scratch test. Furthermore, we evaluated the adhesion, spreading, and proliferation of human gingival fibroblasts (HGFs) and periodontal pathogenic bacteria such as Streptococcus mutans (S.m) and F. nucleatum (F.n) on the surface. Results showed that the elastic modulus, hardness, and adhesive strength of anodized TNTs were significantly enhanced by the incorporation of the D-amino K122-4 peptide. Live-dead staining and SEM observation suggested a decreased surface colonization by both bacterial species. The antibacterial rate of S.m and F. n was 81.5% and 71.7%, respectively, evaluated by colony counting method. Additionally, results of CCK8 assay showed that modified TNTs slightly stimulated HGFs attachment and proliferation while producing enhanced fluorescence of integrin β1 and F-actin, confirmed by laser confocal microscopy observation. Thus, D-amino K122-4 biofunctionalized TNTs present significantly improved mechanical properties, and the mechanically robust structures modulate HGFs proliferation and alignment, resulting in decreased bacteria growth. This novel strategy has the potential to create a surface coating for implants that exhibits superior mechanical robustness and enhanced surface-to-implant interactions.

Solar-light-sensitive applications of recycled iron oxyhydroxide as photoelectrolytic heterostructure by encapsulating in reduced graphene oxide and titanium oxide nanotube array (FeOxrGO/TiNTA)

FeOxrGO/Ti photoanodes by decorating TiO2 nanotube array (TiNTA) with waste iron oxide and reduced graphene oxide (rGO) were synthesized via wet impregnation and calcination. Photoelectrocatalytic (PEC) degradation of azo dye pollutants, accompanied by hydrogen gas evolution, was demonstrated in a dual-chamber divided cell. Characterization showed that the iron oxide recovered from the wastewater treatment plant were crystalline clusters consisting of mineral goethite nanoparticles (αFeOOH NPs) with a visible-light responsive bandgap. Furthermore, the incorporation of rGO led to an enhancement in the electrochemical surface area (ECSA, cm2) of the anode due to its larger capacitive current compared to TiNTA. This improvement facilitated the transport of charge carriers (e- and h+) within a type-II heterostructure of αFeOOH and TiO2. The applied bias photon-to-current conversion efficiency and transient photocurrent density, depending on the composition of iron oxide in FeOxrGO/Ti, substantially increased. 2%wt of iron oxide in FeO2.0rGO/Ti has been optimized in terms of azo dye decolorization, TOC removal, and H2 generation rates (on Pt/G cathode) in 0.1 M Na2SO4 at a working potential of +1.0 V (vs. Ag/AgCl). This study explored the reusability and valorization of Fenton fluidized-bed waste iron oxide with TiO2 for PEC applications.

Preparation of a novel Ti/TNAs/PbO2-PVDF-Er2O3 anode by Ti3+ self-doping TNAs and its electrocatalytic performance for hydroquinone degradation

A new type of Ti/TNAs/PbO2-PVDF-Er2O3 electrode was prepared in this research via composite electrodeposition method with Ti3+ self-doped modified titanium dioxide nanotubes arrays (TNAs) as the intermediate layer, and co-deposition of PVDF and rare earth Er (Ⅲ) into PbO2, which is expected to be used for efficient degradation of hydroquinone (HQ) wastewater. The research results indicate that the Ti/TNAs/PbO2-PVDF-Er2O3 electrode is composed of more compact β-PbO2, possesses the largest hydrophobicity (97.8°) among the series electrodes. Additionally, the electrode exhibits remarkable electrocatalytic performance with the largest oxygen evolution potential (2.012 V), the largest electrochemical active surface area (ECSA), and the smallest electron transfer resistance (1.054 Ω·cm2). Furthermore, the Ti/TNAs/PbO2-PVDF-Er2O3 electrode is used for the degradation of HQ, and the experiments results reveal that the degradation process is mainly controlled by the indirectly oxidation of ·OH generated on the surface of the electrode, which is presumed to be oxidized to benzoquinone and various fatty acids by ·OH in combination with GC-MS, and finally mineralized to CO2 and H2O. Meanwhile, under the optimum degradation conditions (pH:7, temperature: 30 ℃, Na2SO4: 0.1 M, current density: 50 mA.cm‐2), the degradation rate is up to 94.5%, demonstrating the best electrocatalytic degradation efficiency.

Copper and Zinc Co-doped Titanium Dioxide Nanotubes Arrays on Controlling Nitric Oxide Releasing and Regulating the Inflammatory Responses for Cardiovascular Biomaterials.

Titanium dioxide (TiO2) nanotubes arrays have shown tremendous application foreground due to their unique characters of structure and performance. However, the single bio-function is still the limit on cardiovascular biomaterials. The loadability function provides the possibility for the TiO2 nanotubes arrays to realize composite multifunction. The copper can catalyze the release of nitric oxide to promote the proliferation of endothelium cells and improve the anticoagulant. Also, zinc can adjust the inflammatory responses to improve anti-inflammation. In this patent work, we co-doped the copper and zinc onto TiO2 nanotubes arrays to estimate the hemocompatibility, cytocompatibility and responses of inflammation. The results showed that copper and zinc could introduce better multi-biofunctions to the TiO2 nanotubes arrays for the application in cardiovascular biomaterials. In summary, the NTs@Cu/Zn sample as a new composite material in this study had significant biocompatibility in vascular implantation and can be used as a potential material for polymer- free drug-eluting stents.

Photoelectrochemical performance of BiOI/TiO 2 nanotube arrays (TNAs) p-n heterojunction synthesized by SILAR-ultrasonication-assisted methods

In order to extend the visible region activity of titania nanotube array (TNAs) films, the successive ionic layer adsorption and reaction (SILAR)-ultrasonication-assisted method has been used to prepare BiOI-modified TiO 2 nanotube arrays (BiOI/TNAs). The band gap of BiOI/TNAs for all the variations reveals absorption in the visible absorption. The surface morphology of BiOI/TNAs is shown in the nanoplate, nanoflake and nanosheet forms with a vertical orientation perpendicular to TiO 2 . The crystalline structure of BiOI did not change the structure of the anatase TNAs, with the band gap energy of the BiOI/TNAs semiconductor in the visible region. The photocurrent density of the BiOI/TNAs extends to the visible-light range. BiOI/TNAs prepared with 1 mM Bi and 1 mM KI on TNAs 40 V 1 h, 50 V 30 min show the optimum photocurrent density. A tandem dye-sensitized solar cell (DSSC)-photoelectrochemical (PEC) was used for hydrogen production in salty water. BiOI/TNAs optimum was used as the photoanode of the PEC cell. The solar to hydrogen conversion efficiency (STH) of tandem DSSC-PEC reaches 1.34% in salty water.

Effects of Coupled-/soluble-Copper, Generating from Copper-doped Titanium Dioxide Nanotubes on Cell Response.

Endothelialization in vitro is a very common method for surface modification of cardiovascular materials. However, mature endothelial cells are not suitable because of the difficulty in obtaining and immunogenicity. In this patent work, we determined the appropriate amount of copper by constructing a copper- loaded titanium dioxide nanotube array that can catalyze the release of nitric oxide, compared the effects of coupled-/soluble-copper on stem cells, and then induced stem cells to differentiate into endothelial cells. The results showed that it had a strong promotion effect on the differentiation of stem cells into endothelial cells, which might be used for endothelialization in vitro. SEM and EDS results prove that a high content of copper ions are indeed doped onto the surface of nanotubes with small amounts of Cu release. The release of NO confirms that the release of several samples within a period of time is within the physiological concentration.

Photoelectrochemical Water Oxidation Using Cobalt Phosphate‐Modified Nitrogen‐Doped Titania Nanotube Arrays

Water Splitting In article number 2200229, Kazuhiko Maeda, Hyunwoong Park, and co-workers accomplished stable photoelectrochemical water oxidation driven by sunlight to yield oxygen gas with cobalt phosphate-modified, nitrogen-doped titania nanotube arrays, which can absorb visible light with wavelengths as long as 580 nm.

Efficient Electrochemical Oxidation of Chloramphenicol by Novel Reduced TiO2 Nanotube Array Anodes: Kinetics, Reaction Parameters, Degradation Pathway and Biotoxicity Forecast.

The key component of electrochemical advanced oxidation technology are high-efficiency anodes, and highly efficient and simple-to-prepare materials have generated a lot of interest. In this study, novel self-supported Ti3+-doped titanium dioxide nanotube arrays (R-TNTs) anodes were successfully prepared by a two-step anodic oxidation and straightforward electrochemical reduction technique. The electrochemical reduction self-doping treatment produced more Ti3+ sites with stronger absorption in the UV-vis region, a band gap reduction from 2.86 to 2.48 ev, and a significant increase in electron transport rate. The electrochemical degradation effect of R-TNTs electrode on chloramphenicol (CAP) simulated wastewater was investigated. At pH = 5, current density of 8 mA cm-2, electrolyte concentration of 0.1 M sodium sulfate (Na2SO4), initial CAP concentration of 10 mg L-1, CAP degradation efficiency exceeded 95% after 40 min. In addition, molecular probe experiments and electron paramagnetic resonance (EPR) tests revealed that the active species were mainly •OH and SO4-, among which •OH played a major role. The CAP degradation intermediates were discovered using high-performance liquid chromatography-mass spectrometry (HPLC-MS), and three possible degradation mechanisms were postulated. In cycling experiments, the R-TNTs anode demonstrated good stability. The R-TNTs prepared in this paper were an anode electrocatalytic material with high catalytic activity and stability, which could provide a new approach for the preparation of electrochemical anode materials for difficult-to-degrade organic compounds.

Zinc (Zn) Doping by Hydrothermal and Alkaline Heat-Treatment Methods on Titania Nanotube Arrays for Enhanced Antibacterial Activity.

Titanium (Ti) is a popular biomaterial for orthopedic implant applications due to its superior mechanical properties such as corrosion resistance and low modulus of elasticity. However, around 10% of these implants fail annually due to bacterial infection and poor osseointegration, resulting in severe pain and suffering for the patients. To improve their performance, nanoscale surface modification approaches and doping of trace elements on the surfaces can be utilized which may help in improving cell adhesion for better osseointegration while reducing bacterial infection. In this work, at first, titania (TiO2) nanotube arrays (NT) were fabricated on commercially available pure Ti surfaces via anodization. Then zinc (Zn) doping was conducted following two distinct methods: hydrothermal and alkaline heat treatment. Scanning electron microscopic (SEM) images of the prepared surfaces revealed unique surface morphologies, while energy dispersive X-ray spectroscopy (EDS) revealed Zn distribution on the surfaces. Contact angle measurements indicated that NT surfaces were superhydrophilic. X-ray photoelectron spectroscopy (XPS) provided the relative amount of Zn on the surfaces and indicated that hydrothermally treated surfaces had more Zn compared to the alkaline heat-treated surfaces. X-ray crystallography (XRD) and nanoindentation techniques provided the crystal structure and mechanical properties of the surfaces. While testing with adipose-derived stem cells (ADSC), the surfaces showed no apparent cytotoxicity to the cells. Finally, bacteria adhesion and morphology were evaluated on the surfaces after 6 h and 24 h of incubation. From the results, it was confirmed that NT surfaces doped with Zn drastically reduced bacteria adhesion compared to the Ti control. Zn-doped NT surfaces thus offer a potential platform for orthopedic implant application.

ZnP-PEDOT: A potential hybrid coating on titania nanotubes For orthopaedic applications

The current research work is intensively focused on zinc phosphate doped Poly(3,4-ethylenedioxythiophene PEDOT electropolymerized on titania nanotube arrays (TNTA) that fabricated on Cp-Titanum by anodic oxidation process for orthopaedic application. The preliminary characterization studies were conducted to determine the morphology, elemental composition, phase transformation and functional group of the ZnP-PEDOT/TNTA. Moreover, the wettability of the material was tested using water contact angle. The promising corrosion resistance of electropolymerized hybrid material was evaluated from electrochemical impedance spectroscopy and polarization studies. The bioactivity and in vitro biocompatibility were determined by biomineralization studies, where the material was immersed in Hanks’ solution for 21 days. Similarly, (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) MTT assay with MG63 cells was carried out to understand the cell viability and proliferation of the material with the presence of zinc phosphate along with PEDOT. The contribution against the antibacterial performance of zinc phosphate and PEDOT on TNTA implant material was tested using gram-positive and gram-negative bacteria. Overall the obtained outcomes exhibited outstanding biocompatibility, excellent anticorrosion and antibacterial properties. Hence ZnP-PEDOT/TNTA together makes a promising potential hybrid material for bone performance in the orthopaedic field.

Zinc Nanoparticles Electrodeposited on TiO2Nanotube Arrays Using Deep Eutectic Solvents for Implantable Electrochemical Sensors

This work reports on the electrodeposition of zinc on nanoporous metal oxide titania nanotube arrays (TiO2 NTAs) using a zinc-containing deep eutectic solvent (Zn2+–DES). The effects of substrate morphology and crystallinity, deposition temperature, zinc concentration, and deposition time on the morphology and electrochemical properties of the Zn/TiO2 NTAs were investigated. Two-dimensional zinc nanohexagons (NHexs) with a mean diameter of ∼300 nm and a thickness of 10–20 nm were decorated onto the TiO2 NTAs (with a pore diameter of ∼80 nm and a tube length of ∼5 μm) via electrodeposition at −1.6 V using Zn2+–DES. Cyclic voltammetry tests on the Zn2+–DES electrolyte revealed an electrochemical window of ∼3.5 V, and the diffusion coefficient of Zn2+ was found to be 4.29 × 10–10 cm2 s–1 at room temperature and 7.10 × 10–10 cm2 s–1 at 40 °C. Zinc nucleation on TiO2 NTA substrates followed an instantaneous model. Using a higher electrodeposition temperature increased the nucleation and growth rate of zinc NHexs, while annealing TiO2 NTAs was found to improve their uniformity and morphology. During the initial stage of deposition, hexagonal close-packed zinc NHexs were found to preferentially grow on tetragonal anatase TiO2 NTAs. The electrodeposition of zinc resulted in lowering the impedance and improving the overall electrochemical properties of TiO2 NTAs. The Zn/TiO2 NTAs developed in this study offer a promising electrocatalyst material system for implantable electrochemical sensors.

Osseointegration and anti-infection of dental implant under osteoporotic conditions promoted by gallium oxide nano-layer coated titanium dioxide nanotube arrays

The insufficient osteointegration between titanium (Ti) based dental implants and surrounding bone tissue under osteoporotic conditions, as well as implant-associated infections usually associate with dental implant failure. Gallium (Ga) has drawn increasing attention due to its antibacterial ability and pro-osteogenic property. Herein, we established a facile strategy to deposit gallium oxide (Ga2O3) nano-layer on titanium dioxide nanotube (TNT) arrays by magnetron sputtering. Both Ga2O3@TNT/50 W and Ga2O3@TNT/100 W specimens were prepared at different powers (50 W and 100 W), respectively, which all achieved a sustained release of Ga3+ ion for over 14 days. In vitro results showed that Ga2O3@TNT/50 W sample has good biocompatibility and osteogenic activity, compared with TNT and Ga2O3@TNT/100 W samples. Moreover, both Ga2O3@TNT/50 W and Ga2O3@TNT/100 W samples possess potent antibacterial properties, due to the released Ga3+ ion. Furthermore, in vivo results indicated that the Ga2O3@TNT/50 W showed excellent in vivo antibacterial ability and promoted new bone formation effectively compared with TNT implants in an osteoporotic rat model with Staphylococcus aureus (S. aureus) infection. Therefore, such Ga2O3 deposition coating strategy provides a valuable guidance for the potential future development of Ga-doped dental implants and TNT based drug loading surfaces for clinical applications.

The synthesis, surface analysis, and cellular response of titania and titanium oxynitride nanotube arrays prepared on TiAl6V4 for potential biomedical applications

Titania nanotubes are gaining prominence in the biomedical field as implant materials due to their mechanical durability, nano-rough properties, and positive influence on cellular response. This work aimed to synthesize titania and titanium oxynitride (Ti–O–N) nanotubular arrays on TiAl6V4 substrates using an anodic oxidation process followed by annealing in air or by additional nitridation in NH3 atmosphere. Different nanotubular layers of unique morphology and structure were fabricated and investigated using advanced surface analysis and biocompatibility tests. In-depth surface analysis was performed by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), 3D profilometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Cell testing using adipose-derived mesenchymal stem cells and human fetal osteoblasts demonstrated good cell viability, high proliferative capacity, and a favorable overall effect on cell morphology for the Ti–O–N nanotubes.

Double-edged sword of biofouling potentials associated with haemocompatibility behaviour: titania nanotube arrays for medical implant surface technology

BackgroundMedical implant failures are frequently associated with limitations of the surface technology that lead to biofouling and haemocompatibility issues. Titania nanotube array technology could provide a solution for this existing limitation. The present study describes the biofouling potential using the simulated body fluid model according to ISO 23317-2007 and haemocompatibility profiles according to ISO 10993-4 guidelines. Further haemocompatibility profiles were also assessed by evaluating full blood count, coagulation assays, haemolytic rate, whole blood clotting factor, platelet profiles, and FESEM characterization.ResultTitania nanotube array nanosurface was found to present with better apatite biofouling and hydrophilic potential compared to bare titanium foil. Furthermore, good compatibility behaviour was observed based on the haemocompatibility profiles where no signs of thrombogenesis and haemolysis risks were observed. Titania nanotube array reduced fibrinogen adsorption, red blood cell and platelet adhesion and activation, which could be associated with detrimental biofouling properties.ConclusionTitania nanotube array could possess a double-edged sword of biofouling potentials that resist detrimental biofouling properties associated with thrombogenesis and haemolysis risk. It also provides better apatite biofouling potential for improved tissue and osseointegration activities. Knowledge from this study provides a better understanding of medical implant surface technology.Graphical

Effects of Mode of Preparation of Titanium Dioxide Nanotube Arrays on Their Photocatalytic Properties: Application to p-Nitroaniline Degradation

The aim of this study was to investigate the photoactivity of dioxide titanium (TiO2) nanotube films depending on different structure factors including pore size, tube length, tube wall thickness and crystallinity. Aqueous p-nitroaniline was used as a probe to assess the photocatalytic activity of titanium dioxide nanotube layers under UV irradiations. Self-organized titanium dioxide nanotube thin films were prepared by electrochemical anodization of titanium (Ti) foils and Ti thin films sputtered onto silicon (Si). The amorphous as-formed titanium nanotube layers were then annealed at different temperatures ranging from 450 to 900 °C in order to form crystalline phases. The structure and the morphology of the films were characterized by surface analysis techniques and scanning electron microscopy, respectively. The photocatalytic activity of the resulting TiO2 thin films was evaluated by monitoring the UV degradation of p-nitroaniline by UV spectrophotometry and by determining nitrification yields of by ion chromatography. The highest photocatalytic activity was exhibited for titanium nanotubes annealed at 450 °C. The presence of rutile -obtained for an annealing temperature of 900 °C—appeared to reduce the photodegradation yield of p-nitroaniline. Finally, the TiO2 nanotubes obtained from Ti foils revealed the most efficient photocatalytic properties.

Fabrication of CO-releasing surface to enhance the blood compatibility and endothelialization of TiO2 nanotubes on titanium surface

Although the construction of nanotube arrays with the micro-nano structures on the titanium surfaces has demonstrated a great promise in the field of blood-contacting materials and devices, the limited surface hemocompatibility and delayed endothelial healing should be further improved. Carbon monoxide (CO) gas signaling molecule within the physiological concentrations has excellent anticoagulation and the ability to promote endothelial growth, exhibiting the great potential for the blood-contact biomaterials, especially the cardiovascular devices. In this study, the regular titanium dioxide nanotube arrays were firstly prepared in situ on the titanium surface by anodic oxidation, followed by the immobilization of the complex of sodium alginate/carboxymethyl chitosan (SA/CS) on the self-assembled modified nanotube surface, the CO-releasing molecule (CORM-401) was finally grafted onto the surface to create a CO-releasing bioactive surface to enhance the biocompatibility. The results of scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) revealed that the CO-releasing molecules were successfully immobilized on the surface. The modified nanotube arrays not only exhibited excellent hydrophilicity but also could slowly release CO gas molecules, and the amount of CO release increased when cysteine was added. Furthermore, the nanotube array can promote albumin adsorption while inhibit fibrinogen adsorption to some extent, demonstrating its selective albumin adsorption; although this effect was somewhat reduced by the introduction of CORM-401, it can be significantly enhanced by the catalytic release of CO. The results of hemocompatibility and endothelial cell growth behaviors showed that, as compared with the CORM-401 modified sample, although the SA/CS-modified sample had better biocompatibility, in the case of cysteine-catalyzed CO release, the released CO could not only reduce the platelet adhesion and activation as well as hemolysis rate, but also promote endothelial cell adhesion and proliferation as well as vascular endothelial growth factor (VEGF) and nitric oxide (NO) expression. As a result, the research of the present study demonstrated that the releasing CO from TiO2 nanotubes can simultaneously enhance the surface hemocompatibility and endothelialization, which could open a new route to enhance the biocompatibility of the blood-contacting materials and devices, such as the artificial heart valve and cardiovascular stents.

Antibacterial ability of black titania in dark: Via oxygen vacancies mediated electron transfer

Antibacterial ability is greatly demanded for biomedical implants to prevent after-surgery infections. Titania is the oxidative layer of the widely used Ti implants, and is well known to gain antibacterial ability via photocatalysis. However, to prevent the implant related infections, antibacterial ability in dark is required. In this work, we carry out a study on the in-dark antibacterial ability of black titania nanotube arrays (B-TNT) on Ti substrate, and the mechanisms are also deeply investigated. We discover that B-TNT have prominent bactericidal ability in dark, and the mechanisms lie on the electron transfer mediated by the oxygen vacancies (Vo) of B-TNT. With single-electron trapped in their sites, the Vo function as both electron donors and acceptors, generating superoxide anions, hydroxyl radicals and singlet oxygen to do bacteria killing. Moreover, the Vo have the ability to trigger unusual extracellular electron transfer (EET) from the bacteria on B-TNT, which eventually leads to bacteria death. The generation of the Reactive Oxygen Species (ROS) and the force EET mediated by Vo work together to enable the antibacterial ability of B-TNT in dark.

Plasmon induced green synthesized nano silver doped titania nanotubes array for photoelectrochemical (PEC) application

The capillary effect of titanium nanotube arrays (TNTs) was used for in-situ deposition of green synthesized silver nanoparticles (AgNPs) to create hybrid Ag-TNT nanostructures. Titania is a well-known and well-established photocatalyst, although its applications are limited to the ultraviolet region. Under visible light irradiation, the silver nanoparticles, which are recognized for their plasmonics, create the ideal pair as an efficient photosensitizer to promote photocatalytic water splitting. In this approach, a green synthesis method was used to synthesize nano silver colloid, and the silver nanoparticles were then introduced to an anodized titanium plate for incorporation. The photocatalysts are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), UV-VIS-diffuse reflectance spectra, Fluorescence spectroscopy, and X-ray photoelectron spectroscopy (XPS) to explore their structural and optical properties. Time-resolved photoluminescence (TRPL) spectroscopy was employed to understand the charger carrier kinetics and the electrons/holes recombination strategy using the bi-exponential decay function. The visible-light-driven hydrogen production activities of Ag-TNT photocatalysts were evaluated and the hydrogen production rate of Ag-TNT was 12 times higher than TNT. The surface plasmon resonance (SPR) effect of Ag-NPs improves visible-light harvesting and electron transport to the conduction band. The use of the capillary effect to deposit green AgNPs is a simple and promising method for improving Titania-based photocatalyst performance.

Biological properties of hydroxyapatite coatings on titanium dioxide nanotube surfaces using negative pressure method.

Titanium (Ti) exhibits superior biocompatibility and mechanical properties but is bioinert, while hydroxyapatite (HA) possesses excellent osteogenesis and is widely used for the modification of Ti surface coatings. However, the synthesis of homogeneous and stable HA on metallic materials is still a major challenge. In this study, porous titanium dioxide nanotube arrays were prepared on Ti surface by anodic oxidation, loaded with calcium and phosphorus precursors by negative pressure immersion, and HA coating was formed by in situ crystallization of calcium and phosphorus on the surface by hydrothermal heating. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and bonding strength were conducted to confirm the surface characteristics of each group. The cell proliferation, mineralization degree, and alkaline phosphatase (ALP) activity of MC3T3-E1 cells on samples were calculated and compared in vitro experiments. Cylindrical samples were implanted into rat femurs to evaluate biocompatibility and osteogenesis in vivo. The results showed that HA crystals successfully synthesized in TiO2 nanotubes, enhancing the bonding strength of HA coating and Ti substrate under negative pressure. Moreover, HA coating on Ti substrate remarkably enhanced cell proliferation and osteogenic differentiation activity in vitro, and improved new bone formation as well as osseointegration in vivo.

Ruthenium-loaded titania nanotube arrays as catalysts for the hydrogen evolution reaction in alkaline membrane electrolysis

In the present work, we introduce a new electrocatalyst for the hydrogen evolution reaction to be used for alkaline membrane water electrolysis. The new catalyst uses ruthenium as the active phase and titania nanotube arrays, grown onto a non-woven titanium transport layer, as dual-scale porosity support. The original synthetic strategy of the catalyst is reported along with the fundamental characterization of the material. The functionality of the catalyst is evaluated by cyclic voltammetry and linear sweep voltammetry to determine the hydrogen evolution reaction activity of samples with variable loading, to benchmark with state-of-the-art materials. Finally, we present the results of the cathodes when used in a full alkaline membrane electrolyzer. The device is able to deliver a current density that exceed 1 A cm−2 at less than 2 V with Ru loadings lower than 50 μg cm−2. Accordingly, this novel electrode structure with ultralow PGM loading shows an outstanding perspective for the application in alkaline membrane electrolysers, with the added benefit of being easy to handle.