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Objectives: Nanotechnology is constantly advancing in dental science, progressing several features aimed at improving dental implants. An alternative for surface treatment of dental implants is electrochemical anodization, which may generate a nanotubular surface (TiO 2 nanotubes) with antibacterial potential and osteoinductive features. This systematic review and meta-analysis aims to elucidate the possible antibacterial properties of the surface in question compared to the untreated titanium surface., Sources: For that purpose, was performed a systematic search on the bases PubMed, Lilacs, Embase, Web Of Science, Cinahl, and Cochrane Central, as well as, manual searches and gray literature., Study Selection: The searches resulted in 742 articles, of which 156 followed for full-text reading. Then, 37 were included in the systematic review and 8 were included in meta-analysis., Results: Fifteen studies revealed significant antibacterial protection using TiO 2 nanotube surfaces, while 15 studies found no statistical difference between control and nanotextured surfaces. Meta-analysis of in vitro studies demonstrated relevant bacterial reduction only for studies investigating Staphylococcus aureus in a period of 6 h. Meta-analysis of in vivo studies revealed three times lower bacterial adhesion and proliferation on TiO 2 nanotube surfaces., Conclusions: TiO 2 nanotube topography as a surface for dental implants in preclinical research has demonstrated a positive relationship with antibacterial properties, nevertheless, factors such as anodization protocols, bacteria strains, and mono-culture methods should be taken into consideration, consequently, further studies are necessary to promote clinical translatability., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The success of titanium dental implants relies on osseointegration, the load-bearing connection between bone tissue and the device that, in contact osteogenesis, comprises the deposition of bony cement line matrix onto the implant surface. Titanium dioxide nanotubes (NTs) are considered a promising surface for improved osseointegration, yet the mechanisms of cement line integration with such features remains elusive. Herein, we illustrate cement line deposition into NTs on the surface of titanium implants with two underlaying microstructures: a machined surface or a blasted/acid etched surface placed in the tibiae of Wistar rats. After retrieval, scanning electron microscopy of tissue reflected from the implant surface indicated minimal incursion of the cement line matrix into the NTs. To investigate this further, focused ion beam was utilized to prepare cross-sectional samples that could be characterized using scanning transmission electron microscopy. The cement line matrix covered NTs regardless of underlying microstructure, which was further confirmed by elemental analysis. In some instances, cement line infiltration into the NTs was noted, which reveals a mechanism of nanoscale anchorage. This study is the first to demonstrate cement line deposition into titanium NTs, suggesting nano-anchorage as a mechanism for the success of the NT modified surfaces in vivo., (© 2023 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals LLC.)

The entire route from anodic oxidation and surface characterization, including in vitro experiments and finally in vivo osseointegration assays were performed with the aim to evaluate nanotubular and crystalline annealed titanium oxides as a suitable surface for grade 2 titanium permanent implants. Polished titanium (T0) was compared with anodized surfaces obtained in acidic media with fluoride, leading to an ordered nanotubular structure of titanium oxide on the metal surface, characterized by tube diameter of 89 ± 24 nm (Tnts). Samples were thermally treated in air (TntsTT) to increase the anatase crystalline phase on nanotubes, with minor alteration of the structure. Corrosion tests were performed to evaluate the electrochemical response after 1, 14, and 28 days of immersion in simulated body fluid. Based on the in vitro results, heat-treated titanium nanotubes (TntsTT) were selected as a promissory candidate to continue with the osseointegration in vivo assays. The in vivo results showed no major improvement in the osseointegration process when compared with untreated Ti after 30 days of implantation and there also was a lower increase in the development of new osseous tissue., (© 2020 Wiley Periodicals LLC.)

Exosomes are extracellular nanovesicles that play an important role in cellular communication. The modulatory effects of bone morphogenetic protein 2 (BMP2) on macrophages have encouraged the functionalization of scaffolds through the integration of the exosomes from the BMP2-stimulated macrophages to avoid ectopic bone formation and reduce adverse effects. To determine the functionality of exosomal nanocarriers from macrophages after BMP2 stimulation, we isolated the exosomes from Dulbecco's modified Eagle's medium (DMEM)- or BMP2-stimulated macrophages and evaluated their effects on osteogenesis. Morphological characterization of the exosomes derived from DMEM- or BMP2-treated macrophages revealed no significant differences, and the bone marrow-derived mesenchymal stromal cells showed similar cellular uptake patterns for both exosomes. In vitro study using BMP2/macrophage-derived exosomes indicated their beneficial effects on osteogenic differentiation. To improve the bio-functionality for titanium implants, BMP2/macrophage-derived exosomes were used to modify titanium nanotube implants to favor osteogenesis. The incorporation of BMP2/macrophage-derived exosomes dramatically increased the expression of early osteoblastic differentiation markers, alkaline phosphatase (ALP) and BMP2, indicative of the pro-osteogenic role of the titanium nanotubes incorporated with BMP2/macrophage-derived exosomes. The titanium nanotubes functionalized with BMP2/macrophage-derived exosomes activated autophagy during osteogenic differentiation. In conclusion, the exosome-integrated titanium nanotube may serve as an emerging functional material for bone regeneration. STATEMENT OF SIGNIFICANCE: The clinical application of bone morphogenetic protein 2 (BMP2) is often limited by its side effects. Exosomes are naturally secreted nanosized vesicles derived from cells and play an important role in intercellular communication. The contributions of this study include (1) the demonstration of the potential regulatory role of BMP2/macrophage-derived exosomes on the osteogenic differentiation of mesenchymal stromal cells (MSCs); (2) fabrication of titanium nanotubes incorporated with exosomes; (3) new insights into the application of titanium nanotube-based materials for the safe use of BMP2., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Polyacrylic acid-grafted-carboxylic graphene/titanium nanotube (PAA-g-CGR/TNT) composite was synthesized. It was effectively used as adsorbent as well as photocatalyst. The composite was characterized by FTIR, XRD, SEM, TEM, Surface Area Analyzer, XPS and DRS. The photocatalytic activity of PAA-g-CGR/TNT composite was evaluated on the basis of the degradation of pollutants by using sunlight. The band gap of the prepared photocatalyst was found to be 2.6eV. The removal of the antibiotic enrofloxacin (ENR) was achieved by two step mechanism based on adsorption and photodegradation. The maximum adsorption was observed at pH 5.0. The best fitted kinetic model was found to be pseudo-second-order. The maximum adsorption was observed at 30°C. The maximum adsorption capacity was found to be 13.40mg/g. The kinetics of photodegradation of ENR onto PAA-g-CGR/TNT composite follow first-order kinetics and optimum pH was found to be 5.0. The regeneration and reuse of the adsorbent-cum-photocatalyst were also examined upto five cycles., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Anodization is a promising method to change the topography and wettability of titanium (Ti) implant. The formed TiO2 nanotubes (TiNTs) arrays could enhance the biological properties of Ti implants. In this study, to investigate the possibility of TiNTs arrays on a Ti implant surface as nano-reservoirs for small molecular drugs when using in orthopedic and dental prosthesis, TiNTs on a Ti implant surface were prepared. Then, aspirin and/or vitamin C were loaded into TiNTs as model drugs. Meanwhile, low molecular weight polylactic acid (PLA, Mw=3000) was synthesized and loaded alternately along with aspirin or vitamin C. The release rates of aspirin and vitamin C with/or without PLA loading were investigated by using a UV-Vis spectrometer. The results showed that when loading without PLA, drugs released quickly with presence of burst release. However, when loading with PLA, the cumulative release duration of aspirin and vitamin C was prolonged to over 240h. Molecular dynamics (MD) simulation and dissipative particle dynamics (DPD) simulation results proved that when loading with PLA, PLA molecules aggregated gradually and formed clusters or micelles in these nanotubes. Meanwhile, drug molecules were captured and distributed inside the PLA matrix, which retarding the release of drugs. Only when PLA micelles degrade gradually in body fluid, drugs could be released slowly from nanotubes. These knowledge laid ground basis for the following biological experiments., (Copyright © 2016. Published by Elsevier B.V.)

Titanium-based implants have been widely used in orthopedic surgery; however, failures still occur. Our in vitro study has demonstrated that gentamicin-loaded, 80 nm-diameter nanotubes possessed both antibacterial and osteogenic activities. Thus, the aim of this study was to further investigate the in vivo anti-infection effect of the titanium implants with gentamicin-loaded nanotubes. Thirty-six male Sprague Dawley rats were used to establish an implant-associated infection model. A volume of 50 μL Staphylococcus aureus suspension (1×10(5) CFU/mL) was injected into the medullary cavity of the left femur, and then the titanium rods without modification (Ti), titanium nanotubes without drug loading (NT), and gentamicin-loaded titanium nanotubes (NT-G) were inserted with phosphate-buffered saline-inoculated Ti rods as a blank control. X-ray images were obtained 1 day, 21 days, and 42 days after surgery; micro-computed tomography, microbiological, and histopathological analyses were used to evaluate the infections at the time of sacrifice. Radiographic signs of bone infection, including osteolysis, periosteal reaction, osteosclerosis, and damaged articular surfaces, were demonstrated in the infected Ti group and were slightly alleviated in the NT group but not observed in the NT-G group. Meanwhile, the radiographic and gross bone pathological scores of the NT-G group were significantly lower than those of the infected Ti group (P<0.01). Explant cultures revealed significantly less bacterial growth in the NT-G group than in the Ti and NT groups (P<0.01), and the NT group showed decreased live bacterial growth compared with the Ti group (P<0.01). Confocal laser scanning microscopy, scanning electron microscopy, and histopathological observations further confirmed decreased bacterial burden in the NT-G group compared with the Ti and NT groups. We concluded that the NT-G coatings can significantly prevent the development of implant-associated infections in a rat model; therefore, they may provide an effective drug-loading strategy to combat implant-associated infections in clinic.

Nanoscale topography in improving vascular response in vitro was established previously on various titanium surfaces. In the present study different surface nanotopographies that is different diameters of titanium dioxide (TiO2 ) nanotubes (NTs) were fabricated by electrochemical anodization and conditioned with highly reactive gaseous oxygen plasma. The morphology of different diameter NTs was studied by scanning electron microscopy and atomic force microscopy, while changes in chemical composition on the surface before and after plasma treatment were determined by X-ray photoelectron spectroscopy. Performance of human coronary artery endothelial cells (HCAEC) on those conditioned surfaces was studied in regard to cell proliferation, released IL-6 protein and immunofluorescence microscopy (IFM). We show that HCAEC function is dependent on the diameter of the TiO2 NTs, functioning far less optimally when bound to 100 nm TiO2 NTs as compared to Ti foil, 15 nm NTs or 50 nm NTs. There were improved, morphological cell shape changes, observed with IFM, between HCAEC growing on oxygen-rich plasma-treated versus nontreated 100 nm NTs. These endothelialized conditioned Ti nanosurfaces could elucidate optimization conditions necessary for vascular implants in coronary arteries., (© 2016 Wiley Periodicals, Inc.)

Ti-6Al-4V-based nanotubes were prepared on a Ti-6Al-4V surface by anodic oxidation on 10 V, 20 V, and 30 V samples. The 10 V, 20 V, and 30 V samples and a control smooth Ti-6Al-4V sample were evaluated in terms of their chemical composition, diameter distribution, and cellular response. The surfaces of the 10 V, 20 V, and 30 V samples consisted of nanotubes of a relatively wide range of diameters that increased with the voltage. Saos-2 cells had a similar initial adhesion on all nanotube samples to the control Ti-6Al-4V sample, but it was lower than on glass. On day 3, the highest concentrations of both vinculin and talin measured by enzyme-linked immunosorbent assay and intensity of immunofluorescence staining were on 30 V nanotubes. On the other hand, the highest concentrations of ALP, type I collagen, and osteopontin were found on 10 V and 20 V samples. The final cellular densities on 10 V, 20 V, and 30 V samples were higher than on glass. Therefore, the controlled anodization of Ti-6Al-4V seems to be a useful tool for preparing nanostructured materials with desirable biological properties.

To optimize mesenchymal stem cell differentiation and antibacterial properties of titanium (Ti), nano-sized zinc oxide (ZnO) particles with tunable concentrations were incorporated into TiO2 nanotubes (TNTs) using a facile hydrothermal strategy. It is revealed here for the first time that the TNTs incorporated with ZnO nanoparticles exhibited better biocompatibility compared with pure Ti samples (controls) and that the amount of ZnO (tailored by the concentration of Zn(NO3)2 in the precursor) introduced into TNTs played a crucial role on their osteogenic properties. Not only was the alkaline phosphatase activity improved to about 13.8 U/g protein, but the osterix, collagen-I, and osteocalcin gene expressions was improved from mesenchymal stem cells compared to controls. To further explore the mechanism of TNTs decorated with ZnO on cell functions, a response surface mathematical model was used to optimize the concentration of ZnO incorporation into the Ti nanotubes for stem cell differentiation and antibacterial properties for the first time. Both experimental and modeling results confirmed (R (2) values of 0.8873-0.9138 and 0.9596-0.9941, respectively) that Ti incorporated with appropriate concentrations (with an initial concentration of Zn(NO3)2 at 0.015 M) of ZnO can provide exceptional osteogenic properties for stem cell differentiation in bone cells with strong antibacterial effects, properties important for improving dental and orthopedic implant efficacy.

Thermomechanical and impact properties of isotactic polypropylene nanocomposites reinforced with titania nanotubes (TiNTs) at weight distributions of 0.5, 1, and 1.5 wt% were investigated. The goal of this study was to create a novel iPP‐based nanocomposite filament fused filament fabrication (FFF) with improved thermo‐mechanical and impact properties to enable the creation of more customized geometries. First, TiNTs were chemically functionalized with pimelic acid (PA) to promote the β‐crystalline phase using Ca as anchoring. FTIR results revealed the presence of new bands at 1575 and 1413 cm−1, which were attributed to the anchoring of the PA molecule on the TiNT surface. TEM images of the TiNTs confirmed its tubular morphology before and after the functionalization, while the SEM/EDS analysis showed the good dispersion of carbon which can only come from the organic molecule employed in the functionalization. The nano‐reinforcements were incorporated by extrusion generating a filament to produce 3D‐printed specimens. The efficacy of the modified reinforcement as a β‐crystalline phase promoter was evaluated by wide‐angle x‐ray diffraction. The nanocomposite with 1% modified TiNTs showed the highest β‐crystal promotion with a kβ‐index of 89% while the nanocomposites reinforced with unmodified TiNTs reached only 15%. Furthermore, the thermomechanical and impact properties were characterized by dynamic mechanical analysis and Izod. In the first, the storage modulus (E′) was higher than the raw iPP for all nanocomposites, with an increase of about 148% and 107%, while the nanocomposite with a high percentage of β‐crystal showed an increase of 183% in the impact strength properties. A shift of Tg to higher temperatures was attributed to better interfacial interactions polymer/nano‐reinforcement because of the functionalization. The modified nano‐reinforcement was able to generate a 3D‐printed nanocomposite with higher stiffness and impact strength properties than the raw iPP. [ABSTRACT FROM AUTHOR]

The present in vitro study evaluated the effect of titanium nanotubes (nTiO2) application on high translucent zirconia (Copra Supreme, Whitepeaks) on shear bond strength values with different self-adhesive resin cements (Panavia V5, G-Cem One, and Variolink Esthetic DC). One hundred and forty-eight specimens were prepared and randomly divided into four groups (n = 37) according to surface treatment groups (air-abraded sintered zirconia, air-abraded pre-sintered zirconia, application of nTiO2 on zirconia, and application of nTiO2 on air-abraded zirconia). nTiO2 were produced by alkaline hydrothermal synthesis, mixed with isopropyl alcohol (50 wt%), and applied on pre-sintered zirconia. The surface roughness (Ra) was examined. Sintered surfaces were characterized by field emission scanning electron microscope (Fe-SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. Surface treatment groups were randomly divided into three subgroups according to self-adhesive resin cement (n = 12). Luting procedures were performed and specimens were stored in water at 21 °C for 6 months before the shear bond strength test. Data were analyzed by one-way ANOVA and two-way ANOVA. Fe-Sem images and EDS confirmed the incorporation of nTiO2 on zirconia. Surface treatment methods affected the Ra of zirconia (p <.001). Surface treatment method (p =.013) and self-adhesive resin cement (p <.001) affected shear bond strength values. The lowest shear bond strength values were achieved in applied nTiO2 on high translucent zirconia specimens (p <.05). The lowest shear bond strength values were determined in the Variolink Esthetic DC group (p <.05). Application of nTiO2 on air-abraded high translucent zirconia surface had no significant effect on the shear bond strength (p >.05). [ABSTRACT FROM AUTHOR]

In present work, the effect of titania (TiO2) nanotubes formation incorporated with chitosan-58S bioactive glass (TNT/Chitosan-58S BG) on physiochemical properties of titanium substrate was studied. Samples were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Corrosion behavior of the coated samples was investigated in Ringer solution through Tafel polarization and electrochemical impedance spectroscopy measurements. Results represented that TiO2 nanotubes orderly formed on titanium substrate through electrochemical anodizing process. Moreover, Chitosan-58S BG coating was formed on the TNT layer with appropriate adhesion strength, owing to the mechanical interlocking. Variation of applied voltage (25 and 30 V) and duration of anodizing process (30, 60 and 120 min) resulted in the formation of TiO2 nanotubes with various diameters in the range of 89–99 nm. Furthermore, electrochemical evaluations illustrated that the presence of titania nanotubes and Chitosan-58S BG on Ti substrate significantly ameliorated the corrosion resistance of Titanium substrate through reducing corrosion current density (3.486 vs. 2.854 µA cm− 2), as well as, increasing total resistance (40.417 vs. 96.875 kΩ cm2). In addition, our study revealed that the surface hardness of Ti substrate improved after two step surface treatments. In summary, appropriate mechanical and electrochemical characteristics make the TNT/Chitosan-58S BG coating, a proper choice for biomedical applications. [ABSTRACT FROM AUTHOR]

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Photocatalytic CO 2 conversion, in general, requires the incorporation of expensive and noble materials to achieve a highly efficient conversion rate. Herein, the TNT/NiO/CQD ternary nanocomposites without any expensive materials and material modification are fabricated for the demonstration of efficient and economically affordable photocatalytic CO 2 conversion, to our best knowledge, for the first time. The TNT-based ternary photocatalysts are successfully prepared by a simple anodization and immersion process. The TNT/NiO/CQD ternary nanocomposites produce 1.47 μmol·cm-2·h-1 (≈ c.a. 2834 μmol·g-1·h-1) of CH 4 as the sole product under AM 1.5 illumination. This is five times higher performance than that of bare TNT and the performance is comparable to that of any other TiO 2 -based unitary, binary, or ternary photocatalysts. This highly enhanced performance results from effective junction formation between TNT and NiO NP, and the dual role of CQDs as a light absorber and charge transporter/collector in the system. The formation of Z-scheme at the TNT/NiO interface leads to efficient charge transfer via a TiO 2 /NiO bond. The light absorption of the photocatalysts is enhanced and extended by decorated CQDs due to their small band gap. The charge transfer and collection are further improved by charge depletion at the TNT/CQD interface and the charge transfer at the NiO/CQD interface. This work provides a possible model for the realization of efficient and economically affordable photocatalytic CO 2 conversion. [ABSTRACT FROM AUTHOR]

The sorption of Ca2+ on the surface of TiO2 nanoparticles in a saturated solution of Ca(OH)2 was observed by rapid heat evolution compared to the reference sample using isothermal calorimetric analysis. In addition to that, the interaction of TiO2 nanoparticles with a saturated Ca(OH)2 solution under hydrothermal conditions (40, 80, and 120°C) in an autoclave was carried out as well. Perovskite formed as a result of interaction between TiO2 and saturated Ca(OH)2 under temperatures of 80 and 120°C. Similarly, the formation of perovskite was found along with a hydration product when tricalcium silicate was hydrated in the presence of TiO2 nanotubes under hydrothermal condition (120°C). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the presence of perovskite. [ABSTRACT FROM AUTHOR]

Highlights • A highly conductive electroactive polyaniline (PANI) was electrodeposited uniformly on titania nanotubes (TNTs) substrate. • Titania nanotubes-polyaniline (TNTs-PANI) showed antibacterial activity and corrosion resistivity. • The biointerface TNTs-PANI was used as basal substrate for PC12 cells regeneration and differentiation. • The flexible TNTs-PANI substrate accelerated the neurites outgrowth of PC12 cells. Abstract Biologically active conjugated polymers, for example polyaniline (PANI), have drawn attention as emerging materials for applications in bio-medical implant devices, due to their inherent abilities with regard to charge-carrier properties, and their ability to immobilize biomolecules or proteins. Herein, we report an electrocoating of PANI on titania nanotubes (TNTs) via electrochemical oxidation of aniline with PANI layers of appropriate thickness (∼274 nm). Uniform titanium oxide nanotubes were first developed from titanium (Ti) foil through an anodization process, followed by calcination to obtain high purity TNTs vertically aligned on a Ti substrate. These had a large surface area, controllable tube height and diameter, and were highly biocompatible, and doping with PANI further improved their properties, like being antibacterial, having a lower charge transfer resistance (22.51 Ω) and strong anti-corrosion behavior (E corr ∼ − 184 mV, I corr ∼ 9.7 × 10−7 Amp). In vitro experiments revealed that the cellular functions of PC12 and S42 cells on TNTs-PANI scaffolds show characteristic improvement in proliferation and differentiation owning to approach neuronal cells activation associated with axonal growth and migration in the peripheral nervous system (PNS). Thus, the flexible bioactive substrate is capable of stimulating neuronal cells, and can inspire neural transduction through direct neural interfaces. [ABSTRACT FROM AUTHOR]

The paper discusses the synthesis, photoelectrochemical and electrochemical behaviour of titania nanotube arrays modified by a pyrolyzed metal-organic framework (MOF). A poly(3,4–ethylenedioxyphene) (PEDOT) matrix with an embedded inorganic network of iron hexacyanoferrate (BP) covering TiO 2 nanotubes (TNT) is used as a MOF for the further sintering procedure, resulting in a novel, thin film of carbonaceous wrap supported Fe catalytic centers: TNT@C:Fe. UV–Vis and Raman spectroscopies were utilized to characterize the absorbance capability and the crystalline phase of titania, respectively. XPS was used for identification of the valence stage of iron Fe(0), Fe(II), Fe(III) in the shell part of the novel composite TNT@C:Fe. The electrochemical performance of the modified nanotubular TiO 2 electrodes has been monitored by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge cycles in an aqueous electrolyte. TNT@C:Fe exhibited the capacitance of 9.1 mF cm −2 even after 5000 cycles, being much higher than pure titania (2.1 mF cm −2 ). The photocurrent density reached 304 μA cm −2 for TNT@C:Fe, whereas only 32 μAcm −2 was registered for pure titania nanotubes under simulated solar light illumination at a potential of +0.5 V. An improved decolorization rate of methylene blue in water confirms enhanced photoactivity of TNT@C:Fe in comparison with pristine titania nanotubes. [ABSTRACT FROM AUTHOR]

Titania nanotubes are widely studied for their potential applications in several fields. In this paper, the electrochemical characterization of a dental implant, made of commercially pure titanium grade 2, covered by titania nanotubes, when immersed in Hank's solution, is proposed. Few papers were found in the scientific literature regarding this topic, so a brief review is reported, concerning the use of some equivalent circuits to model experimental data. The analysis of results, obtained by using Electrochemical Impedance Spectroscopy, showed that: (i) a good correlation exists between the variation of Ecorr and the estimated values of the charge transfer resistance for both the bare- and the nanotube-covered samples, (ii) the nanostructured surface seems to possess a more active behaviour, while the effect could be over-estimated due to the real extent of the surface covered by nanotubes, (iii) the analysis of the "n" parameter, used to fit the experimental data, confirms the complex nature of nanostructured layer as well as that the nanotubes are partially filled by compounds containing Ca, P and Mg, when immersed in Hank's solution. The results obtained in this work give a better understanding of the electrochemical behaviour of the nanotubes layer when immersed in Hank's solution and could help to design a surface able to improve the implant osseointegration. [ABSTRACT FROM AUTHOR]

It is recommended in the exploitation of catalyst for hydrogen generation from photoelectrochemical (PEC) water splitting to use stable, non-toxic and chemically inert electrodes. The objective in this work is to combine the merits of large surface area and absorption in ultraviolet light–visible light range of hybrid structure of titanium carbide (TiC) thin film deposited on titanium dioxide (TiO 2 ) nanowires (NWrs), nanosheets (NShts) and nanotubes (NTbs). TiO 2 NTbs were prepared by rapid breakdown anodic oxidation technique, while, TiO 2 NWrs and TiO 2 NShts were prepared by hydrothermal method. TiC thin film is deposited on TiO 2 NWrs, TiO 2 NShts and TiO 2 NTbs by radio frequency (RF) magnetron sputtering. Consequently, the absorption threshold of TiO 2 is moved into visible spectrum range and led to a significant improvement in the photocurrent in comparison to bare TiO 2. The samples were characterized by XRD, SEM, UV/Vis and Raman spectroscopy. The chemisorption (active) surface area of the synthesized nanostructures was measured by BET technique and found to be in the order of TiO 2 NTbs < TiO 2 NShts < TiO 2 NWrs. The influence of the specific surface area on the PEC properties of TiC/TiO 2 NWrs, NSts and NTbs is investigated, and a direct proportion between surface area and photocurrent is identified. The impedance measurement has been correlated with the photocurrent-potential properties, so, the hydrogen generation efficiency. The reaction mechanism is briefly discussed. [ABSTRACT FROM AUTHOR]

TiO 2 nanotubes, nanofibers and nanowires were prepared by the hydrothermal treatment of TiO 2 nanoparticles with different NaOH concentrations (5, 10 and 12 N) at 120, 140 and 180 °C; afterwards, HCl was added until reaching pH 2. Both the crystalline phase and coordination of the TiO 2 nanotubes, nanofibers and nanowires were composed principally of H 2 Ti 3 O 7 , H 2 Ti 4 O 9 ·H 2 O and H 2 Ti 5 O 11 ·H 2 O. Likewise, the surface area, pore volume and pore size of the TiO 2 nanotubes, nanofibers and nanowires changed with the NaOH rinsing treatment. The photocatalytic activities for methylene blue and methyl orange degradation were strongly enhanced by the nanotubes and nanoparticles in the basic and acid media, respectively, showing a relationship between their structure and the medium. [ABSTRACT FROM AUTHOR]

H2 production from water splitting by a photocatalytic process is one route that can be used to solve global issues related to energy depletion and environmental pollution, and it has attracted a great amount of attention in both the academic and industrial fields. TiO2 nanotube arrays are intensively investigated as TiO2 catalysts. In comparison to a TiO2 powder catalyst, the nanotube arrays have specific advantages, including a large surface area, easy retrievability, uniformly ordered structure, and size-dependent properties, all of which make them attractive in wide applications including H2 generation. In recent years, a large amount of work has been done and great progress has been achieved in this field. In this review, we summarize synthetic strategies to prepare TiO2 nanotube arrays and their modification methods, and we highlight recent progress in the generation of H2 on TiO2 nanotube-array-based materials. Finally, challenges associated with industrial application of this photocatalytic technique are also emphasized. [ABSTRACT FROM AUTHOR]

Acetaminophen is commonly used as an antipyretic or analgesics agent and poses threat to human health. In this research, TiO 2 and graphite oxide were used as precursors of titanium dioxide nanotubes and graphene respectively. Titanium dioxide nanotube and graphene (GR-TNT) nanocomposites were synthesized through a hydrothermal method. FT-IR, UV-Vis, XRD, and TGA were used to characterize the catalysts. The acetaminophen degradation rate can reach up to 96% under UV light irradiation for 3 h and with the 5% GR-TNT dosage of 0.1 g L −1 . Further experiments were done to probe the mechanism of the photocatalytic reaction catalyzed by the GR-TNT composite. EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system. The results showed that the holes are the main oxidation species in the photocatalytic process. This study provides a new prospect for acetaminophen degradation by using high efficiency catalysts. [ABSTRACT FROM AUTHOR]

The article investigates the anodic titanium dioxide nanotube arrays. Topics discussed include different synthesis approaches to produce titanium dioxide nanotubes and titanium nanotubes arrays, physical and chemical properties, and techniques to modify it such as doping of hydrothermal tubes, self-doping, and self-assembled monolayers. Also mentioned are the applications of nanotubular titanium dioxide including dye-sensitized solar cells, photocatalysis and sensors.

In this paper, carbon modified titanium dioxide nanotubes (hereafter denoted as CTNTs) were synthesized via a hydrothermal method, followed by ethanol washing and then heat-treatment steps. The physicochemical properties of CTNTs were investigated by XRD, BET, HR-TEM, TG-FTIR and UV-Vis spectra. The resultant CTNTs were then utilized for the removal of elemental mercury (Hg0) under the irradiation of visible light LED. Experimental results revealed that the CTNTs had a good adsorption capability and photocatalytic oxidation ability for the removal of Hg0, particularly for the catalyst that was calcinated at 300 °C. We proposed that the activity promotion for the CTNTs was mainly attributed to three aspects: the abundant adsorption sites for Hg0, the well sustained nanotubes structure and the expanded light adsorption spectrum of CTNTs. Furthermore, the roles of influence factors such as empty bed retention time, O2 concentration, SO2 concentration and NO concentration, were investigated. The experimental results verified that white light LED lamp was a suitable light source for the application of photocatalytic oxidation process. [ABSTRACT FROM AUTHOR]

Abstract: TiO2 nanotubes were prepared by the hydrothermal treatment of TiO2 particles with different NaOH concentrations (5, 7, 10 and 12N) at 140°C; afterwards, HCl was added until reaching pH1. Both the crystalline phase and coordination of the TiO2 nanotubes, composed principally of H2Ti3O7 and H2Ti4O9·2H2O, were significantly affected by the NaOH rinsing treatment. Likewise, the surface area, pore volume and pore size of the TiO2 nanotubes changed with the NaOH rinsing treatment. Finally, the NaOH rinsing treatment exerted a notable effect on the generation of Brönsted sites, which is shown by the following sequence: NT7>NT10>NT12>NT5; meanwhile Lewis sites were only present on the NT5 sample. [Copyright &y& Elsevier]

The purpose of this study was to develop novel nanoscale biosensors using titania nanotubes (TNTs) made by anodization. Titania nanotubes were produced on pure titanium sheets by anodization at room temperature. In this research, the electrolyte composition ethylene glycol 250 mL/NH4F 1.5 g/DI water 20 mL was found to produce the best titania nanotubes array films for application in amperometric biosensors. The amperometric results exhibit an excellent linearity for uric acid (UA) concentrations in the range between 2 and 14 mg/dL, with 23.3 (µA⋅cm-2)(mg/dL)-1 UA sensitivity, and a correlation coefficient of 0.993. The glucose biosensor presented a good linear relationship in the lower glucose concentration range between 50 and 125 mg/dL, and the corresponding sensitivity was approximately 249.6 (|µA⋅cm-2)(100 mg/dL)-1 glucose, with a correlation coefficient of 0.973. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous and anatase TiO2 nanotube layers were synthesized by means of Ti foil anodic oxidation performed in ethylene glycol based electrolyte containing fluoride ions. A typical surface structure of TiO2 nanotubular layer, well aligned nanotubes with inner diameter of 70–100nm and wall thickness of about 10–15nm was obtained. Both amorphous and converted to anatase nanotube layers were mechanically stable and well adherent to the Ti current collector. The nanostructured Ti/TiO2 layers were tested as a current collector – anode material system for Li-ion intercallation in 1M LiPF6 ethylene carbonate/dimethyl carbonate (EC:DMC) and in 1-buthyl-1-methyl pyrrolidinium is (trifluoromethyl) sulfonylimide ([BMP][TFSI]) containing 1M Li[TFSI]. The potential window of [BMP][TFSI] measured on Ti current collector remains not considerably influenced by addition of Li[TFSI]. The type of electrolyte does not influence the voltammetric behavior of the amorphous TiO2 nanotube layers, whereas in case of anatase there is a definite inhibition of the Li intercalation in 1M Li[TFSI] [BMP][TFSI], expressed by increasing the peak-to-peak voltage difference between the Li insertion and de-insertion processes. The observed phenomenon is discussed in terms of viscosity difference between both electrolytes. TiO2 nanotube structures displayed a stable galvanostatic cycling, reaching the theoretical capacity of TiO2 structure and high current efficiencies in both Li ion containing media. [Copyright &y& Elsevier]

Highlights: [•] A simple and efficient strategy was used for the preparation of Pt/TiO2 nanotube. [•] The electrode exhibited good electrochemical performance and excellent stability. [•] The performance of electrode is still stable after holding at 1.6 V vs.NHE for 100h. [Copyright &y& Elsevier]

High-aspect-ratio titanate nanotubes (NT) and nanowires (NW) wereproduced by the hydrothermal conversion of TiO2at 400K. The titanate morphology was studied by high-resolution transmissionelectron microscopy (HRTEM). The formation of ordered titanate nanoobjectsdepended on the time of conversion. Shorter synthesis times favoredhollow nanotube production while during prolonged treatment the thermodynamicallymore stable nanowires were formed. Titanate nanotubes and nanowireswere decorated by Rh nanoparticles. The structure and stability oftitanate nanocomposites were studied by thermal gravimetric (TG),X-ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS),Fourier transformed infrared spectroscopic (FTIR), and Raman spectroscopicmethods. The nanowires preserve their structure up to 850 K, whilethe nanotubes start to recrystallize above 600 K. FTIR measurementsshowed that the water and hydroxyl content gradually decreased withincreasing temperature in both cases. XPS data revealed the existenceof high binding energy, highly dispersed Rh species on both supports.A small portion of Rh may participate in an ion exchange process.Support transformation phenomena were observed in Rh containing titanatenanowires and nanotubes. Rh decorated nanowires transform into theβ-TiO2structure, whereas their pristine counterparts’recrystallize into anatase. The formation of anatase was dominantduring the thermal annealing process in both acid treated and Rh decoratednanotubes. Transformation to anatase was enhanced in the presenceof Rh. The average diameters Rh nanoparticles were 4.9 ± 1.4and 2.8 ± 0.7 nm in the case of nanowires and nanotubes, respectively. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the possibility of using a TiO2 anode as an alternative to the Li electrode in Li–air and Li-ion rechargeable batteries. TiO2 nanotube layer is fabricated by the anodization method and optional thermal treatment is conducted. The electrochemical charge/discharge profile of the TiO2/liquid electrolyte/LiCoO2 structured cell is measured under the flowing of O2, N2 and Ar, respectively. The elevation of the upper cut-off voltage from 3 to 4.5 V leads to an increase in the specific capacity by a factor of more than three. We suppose this to be a novel mechanism in which the TiO2/LiCoO2 system under the oxygen atmosphere works in Li–air battery mode up to 3 V and then works in Li-ion battery mode from 3 V to 4.5 V. This idea is confirmed by ICP-OES analysis. [Copyright &y& Elsevier]

In the past few years, a wide range of functional applications of self-functional TiO2 nanotube layers have been explored, ranging from photocatalysis, solar energy conversion, electrochromic effects to the use of the material as a template or catalyst support for applications in the field of health, energy or environment. The present paper provides an overview of TiO2 nanotube layers with tubular structures, grown by controlled anodic oxidation (anodization) on a metallic substrate as titanium. Then, the authors summarize the works reported in the last five years which study the effect of the experimental conditions in the structural and morphological characteristics of TiO2 nanotube superficial layers, where experimental conditions and key properties of these tubular layers are pointed out. Despite the fact that the first works about the highly ordered TiO2 nanotube arrays were reported at the beginning of XXI century, this field has grown so rapidly as to make it difficult to summarize the scope of all related work. The authors classified the different works taking into account the composition of the electrolyte used in the anodization, the base material and studied properties that allow their future application in fields as health, energy or environment, mechanistic aspects of the tube growth and the electrochemical conditions to be fulfilled in order to synthesize these layers are also described. [ABSTRACT FROM AUTHOR]

Abstract: A novel hydrogen peroxide biosensor has been designed based on the co-immobilization of hemoglobin (Hb), TiO2 nanotubes and methylene blue (MB) onto a glassy carbon (GC) electrode. The titania nanotube arrays were directly grown on a Ti substrate using anodic oxidation first; and then detached from the Ti substrate using ultrasonication. A pair of well-defined redox peaks of Hb, enhanced by MB, appeared at an applied potential around −0.425V, revealing that the immobilized Hb exhibits direct electrochemistry. Our electrochemical study shows that the immobilized Hb remains highly bioactive and displays excellent electrocatalytic response toward H2O2. The effect of pH and applied electrode potential in H2O2 sensing has been systemically studied. Besides the advantages of fast response and high stability, under the optimized conditions the linearity of the developed biosensor for the detection of H2O2 was observed from 2×10−7 to 1.6×10−4 M with a detection limit as low as 8×10−8 M (based on S/N =3). [Copyright &y& Elsevier]

Titanium nanotubes were hydrothermally synthesized via a two-step method for ODS (oxidative desulfurization). The catalysts' structures were characterized by XRD (X-ray diffraction), FT-IR, UV-Vis (UV-Vis diffuse reflectance spectra), NH3-TPD, etc. The effects of O/S molar ratio and catalyst dosage, etc., were systematically investigated. The catalyst exhibited remarkable performance, so that the removal of DBT (dibenzothiophene) was nearly 100% under the optimal conditions in 10 min. Also, the catalysts could be easily reused for six consecutive cycles. The hydrogen-assisted thermocatalytic mechanism over titanium nanotubes for ODS was also studied and an effective reactant concentration (ERC) number of 70.8 was calculated. [ABSTRACT FROM AUTHOR]

The main disadvantage of the implants is the associated infections. Therefore, in the long term, the possibility of improving the antibacterial capacity of different types of implants (dental, orthopedic) is being researched. The severity of the problem lies in the increasing bacterial resistance and finding appropriate alternative treatments for infectious diseases, which is an important research field nowadays. The purpose of this review is to draw a parallel between different studies analyzing the antibacterial activity and mechanism of silver nanoparticles (NP Ag) deposited on the titanium nanotubes (NTT), as well as the analysis of the NP Ag toxicity. This review also provides an overview of the synthesis and characterization of TiO2-derived nanotubes (NT). Thus, the analysis aims to present the existing knowledge to better understand the NP Ag implants benefits and their antibacterial activity. [ABSTRACT FROM AUTHOR]

A one-step process combining the photocatalytic degradation of radionuclide complexes and the adsorption of liberated radionuclides on titanium dioxide nanotubes was developed and tested for the purification of aqueous waste produced from chemical decontamination of nuclear power plant circuit components. Among the tested forms of TiO2, only nanotubes exhibit both high photocatalytic activity and sorption ability, which support their application in a one-step purification process. The obtained results indicate that the photocatalytic degradation of complexes followed by the sorption of the radionuclides onto TiO2 nanotubes offers a promising route for treating spent decontamination fluids. [ABSTRACT FROM AUTHOR]

Anodic oxidation is an easy and cheap surface treatment to form nanostructures on the surface of titanium items for improving the interaction between metallic implants and the biological environment. The long-term success of the devices is related to their stability. In this work, titanium nanotubes were formed on a dental screw, made of titanium CP2, through an anodization process using an “organic” solution based on ethylene glycol containing ammonium fluoride and water. Then, the electrochemical stability in the Hank’s solution of these “organic” nanotubes has been investigated for 15 days and compared to that of titanium nanotubes on a similar type of sample grown in an inorganic solution, containing phosphoric and hydrofluoridric acids. Morphological and crystallographic analysis were performed by using scanning electron microscopy (SEM) and X-Ray diffractometry (XRD) tests. Electrochemical measurements were carried out to study the stability of the nanotubes when are in contact with the biological environment. The morphological measurements revealed long nanotubes, small diameters, smooth side walls, and a high density of “organic” nanotubes if compared to the “inorganic” ones. XRD analysis demonstrated the presence of rutile form. An appreciable electrochemical stability has been revealed by Electrochemical Impedance Spectroscopy (EIS) analysis, suggesting that the “organic” nanotubes are more suitable for biomedical devices. [ABSTRACT FROM AUTHOR]